CMOS battery also know as RTC battery
Any laptop computer has a CMOS battery also known as RTC battery. The CMOS battery connects directly to the laptop system board and helps to retain important BIOS settings such as system time, date, BIOS configuration while the laptop is turned off or even when the main battery is removed.
The CMOS battery is rechargeable and it’s getting charged when the laptop is plugged into the mains.
CMOS batteries come in different shapes ans sizes.
On the picture below you see a basic coin cell CMOS battery. This type of batteries usually found in older laptops. This battery is removable and replaceable.
Here’s another type of CMOS battery. Basically, it’s two coin cell batteries but they are bundled together and have a cable which plugs into the system board. This battery is removable and replaceable.
On the next picture you see a CMOS battery which is soldered to the system board. In order to replace this type of battery, you’ll have to unsolder it from the system board.
CMOS BATTERY LOCATION IN A LAPTOP.
In some laptops the CMOS battery could be easily accessed from the bottom, as it shown on the picture below. As an example I took a Dell Inspiron 1720.
In some laptops the CMOS battery is hidden under the keyboard. As an example I took a HP Compaq nc6400 laptop.
Here’s the worst case scenario. The CMOS battery is hidden under the laptop cover. In order to access and replace the battery you’ll have to disassemble the whole laptop. As an example I took a Toshiba Satellite A305 laptop.
CMOS BATTERY RELATED PROBLEMS.
Here’s the most common problem related to the CMOS battery.
Each time you turn off the laptop it resets date and time back to factory defaults. When you turn the laptop back on it asks you to set date and time. If that’s the case, most likely your CMOS battery is old and has to be replaced.
By the way, removing the CMOS battery on most newer laptops will not clear the BIOS password.
Laptop parts | Repair Man | 
December 26, 2008 3:04 pm
December 29th, 2008 at 9:35 am
My laptop will not start at all. When I press the power button nothing happens. Do you think the CMOS battery is dead?
December 29th, 2008 at 10:13 am
Serge,
I don’t think so. From my experience I can tell that your laptop should start even if the CMOS battery is removed.
Without CMOS battery you will not be able to save settings (date, time, etc…) but the laptop should start.
Check the AC adapter. It’s possible that your adapter is dead and the battery discharged. You can test your adapter with a voltmeter. Make sure it outputs correct voltage.
January 1st, 2009 at 12:04 pm
Hi Repair Man. I opened all covers on the laptop and even removed keyboard. I cannot find the battery anywhere. Maybe my laptop doesn’t require one?
January 1st, 2009 at 1:50 pm
Debra T,
Nope, there must be a battery somewhere. I guess it’s buried somewhere inside the laptop and you just cannot find it.
January 2nd, 2009 at 3:16 pm
I found the battery!!!
It was under the laptop cover.
January 3rd, 2009 at 3:26 pm
Man! Searched everywhere and couldn’t find CMOS battery for my Sony notebook. Finally found it at PCHub. No time and date resets anymore!
January 9th, 2009 at 8:53 am
one day my 1year old toshiba started asking for a paassword but i never had a password. i cannog start windows. can i clean the password? do i have to replace cmos battery?
January 9th, 2009 at 10:06 pm
alan,
I know that some newer Toshiba laptops can set the BIOS password on its own. Check out this Toshiba support bulletin, it’s related to your problem.
Toshiba will clear the BIOS password on some Satellite A100, A105, A135, A205, L35, M200, P100, P105, P205 laptops at no charge even if your laptop is not under warranty anymore.
January 12th, 2009 at 11:10 pm
I had a password on my HP laptop. I cannot clear the password. I tried everything. I removed the main battery and CMOS battery for 1 day and the password is still there.
Probably have to send it to HP now.
Does anyone know how to remove BIOS password on HP laptops?
January 13th, 2009 at 2:16 pm
charlotte,
On most newer laptops you cannot erase the password by removing the CMOS battery. I think you’ll have to contact HP customer service and see if they can help you.
February 19th, 2009 at 11:06 am
I have a soldered-on RTC battery on a toshiba satellite m115 and would appreciate a detailed description of how to replace it.
Please help!
February 19th, 2009 at 4:56 pm
hi, im glad to read that im not the only one who cant find the cmos battery, i have tried to dis assemble the case so i can take a look inside but cant get it off, my laptop is a tosh a210-171. where can i find instructions to do this.
many thanks.
ps, already searched tosh`s website
February 24th, 2009 at 8:19 pm
Hoban1962,
What is your reason for replacing the RTC battery?
If you are trying to clear the BIOS password, replacing/resoldering the battery is not going to help.
How exactly do you want me to help you? If the battery is bad, you simply unsolder the old one and replace it with a new one (if you can find it).
February 24th, 2009 at 8:24 pm
garry,
In a Toshiba Satellite A210/A215 the CMOS battery is soldered to the motherboard. You’ll find some disassembly instructions at http://www.irisvista.com/tech/
If you cannot find your particular model, search for similar models.
By the way, as I mentioned in the previous comment, removing the CMOS battery in this model will not help you to clear the BIOS password.
Is it your reason for accessing the battery?
Some newer Toshiba laptop can set the BIOS password on its own. You’ll find more information in this post.
March 2nd, 2009 at 5:04 pm
I have a Toshiba L15-104, and I am experiencing no boot up. The HDD spins, a few lights flash, but the screen does not turn on. I recently bought a battery, and charged it. I have been told that the CMOS battery could be dead. I took apart the laptop twice, trying to find anything that resembles a battery or wires attached to a battery. No luck, I did discover, a plug that is not in use that is white with 2 leads that could connect to it.
This is about a 5 yr old system. I took it into repair a year ago, and am wondering if they “neglected” to replace the CMOS battery. I no longer have the warranty on it. Any help, please. Or the part number for this battery.
March 3rd, 2009 at 7:30 am
My Toshiba satellite M40X stop afer 3 or 4 mn….every time i put it on , it stop again (black screen, no message…) and i need to wait 1 hour then i can start it again, then it stop after 3 mn.
I hav verify ther is no heat, the computer is well cold…
I have oppened it to change the cmos battery, but i didnt find it.
My computer is 5 yrs old.
Thanks
March 3rd, 2009 at 8:54 am
Dizteck,
I don’t think that your problem is related to the CMOS battery.
From my experience I can tell that your laptop should start even if the CMOS battery is completely dead or missing. With a bad CMOS battery you cannot save BIOS settings but it shouldn’t prevent the laptop from booting into Windows. If you set date/time or change settings in the BIOS, they will be reset back to defaults on the next reboot.
Most likely the CMOS battery is soldered to the motherboard, as is done on many newer Toshiba laptops. As an example, take a look at the third picture.
Does it sound like the laptop is working fine except the screen? Can you test the laptop with an external monitor? Can you get video on the external monitor at all?
If both the internal and external monitor do not work, your problem could be related to the memory module. How many memory modules do you have installed?
If you have only one module, try reseating it. Try installing it into the empty slot.
If you have two modules installed, try removing them from the laptop one by one. Test your laptop with each module separately.
March 3rd, 2009 at 9:09 am
bruno645,
What exactly it’s doing? Can you see the Toshiba logo on the screen? Will it start loading Windows and then dies?
I believe your Satellite M40X is similar to a Satellite M35X in which the CMOS battery is soldered to the motherboard. I really doubt that replacing the CMOS battery will help to fix the problem.
You can troubleshoot the problem as it explained in this article:
Laptop is dead. How to troubleshoot the problem.
The laptop in that article should be similar to your laptop.
March 3rd, 2009 at 11:16 am
I have 2 memory chips, I had taken the laptop apart 2 times, resetting everything that was removed. Like I mentioned, I don’t see the screen light up nor do I see all the lights light up. On a normal boot, I would have seen the screen go to windows start, the light for the WiFi on the front would light up–that’s on a normal boot. But, for some reason, when I turned on the laptop the next day it experienced what I mentioned. Push on button, lights flash normally, HD spins, then stops with no monitor activity. I tried plugging in an external monitor, but with this Toshiba, I would have to press the Function Key and another key to toggle between outputs. My final assumption is that, either the Motherboard has failed but, I understood it was replaced one year ago, included in the warranty.
March 3rd, 2009 at 11:37 am
Dizteck,
I believe that if you start the laptop with an external monitor already connected to the VGA port, you don’t have to use the function key. The external monitor should be detected automatically. If you cannot get any video on the external monitor, apparently there is no video signal coming from the motherboard.
I guess your assumption is correct, you have a failed motherboard.
March 14th, 2009 at 5:05 am
Repairman,
I have a HP NX9110 that is locked down with a BIOS password. I have contacted HP in regards to this matter, only to find out that at a considerable cost, they will fix it. The cost was astronomical, it was more beneficial to go and by a new laptop, so I did *Smiles. So I naturally I have a doorstop, that is sitting there, now at this stage I have disassembled the NX9110, and I am wondering if it is salvagable, by either shorting the battery out, or using the jumpers to reconfigure this computer, or even flashing the bios completely. As this is a later model, I am wondering if tinkering with it, will reborn this doorstop again, your guidance on this matter would be greatly appreciated.
March 15th, 2009 at 1:49 pm
Jase,
I don’t know if it’s possible to clear the BIOS password on this model via jumpers, HP doesn’t share that information. I really doubt that removing the CMOS battery will help you.
I guess the only way to make it work again is replacing the motherboard. You can find a new motherboard by the HP part number. Usually the part number could be found on a sticker by the memory slot.
Also, search for HP BIOS password on ebay. Looks like some people offer BIOS password removal services.
March 17th, 2009 at 7:12 am
Hi! I’ve got a toshiba satellite p100-227. It appears that the rtc battery is the problem. I have updated bios, checked conflicts etc, but to no gain. Everytime i change time/date (f2 during boot), it remains that way after restart. The computer is about 2,5 years old, (is it normal to have to change battery after only two years?) However i did remove the main batteryback for about a month to save it from going bad, then reincerted it(computer was connected to mains all the time). Can this be the reason the rtc has gone sour on me so fast?! Is there any possibility that it will recharge? Do you have a oem partnumber for this battery? Great site btw!
March 17th, 2009 at 9:52 pm
johan,
I think it should last longer. I see a lot of different laptops every day. Some of them are over 5 years old with a good working original CMOS battery.
Definitely. Plug in the main battery and charge it overnight. Most likely your CMOS battery will recharge too.
March 18th, 2009 at 1:28 am
Repairman, I’ve read a thread at the toshiba forum about this problem. Some people had the same prob. One guy sent his p100 for fixing and what they did was to remove the rtc for a while and then reincerting it, this did the trick. My warranty has expired and i found a great step-by step instruction on how to get to that little bugger, so i’ll go ahead and try this. BTW. yesterday i experienced that the clock doesn’t even work properly while computer is on; it was reset in bios at 20,25 and after several hours it was showing 20,48, so it “jumps” back to 20,25, but never before 20,25! It works a couple of hours, tops, and then resets, weird… I’ll let you know how it went!!
April 27th, 2009 at 11:46 pm
I’m also a computer technician, and i found your website very informative, it adds up my knowledge about computer repair, most especially laptops
May 8th, 2009 at 1:26 pm
Hi. Please does anyone know the specifications of the RTC/CMOS battery ML1220 of the Toshiba Satellite A135?
I know that is is 3V, but I have no idea about mAh, if 15 or 36mAh or what?
If anyone knows, please let me know.
Thanks.
May 8th, 2009 at 1:32 pm
Aza,
I think this battery is 15mAh. Check out this specifications for Sanyo Lithium Cell Type ML1220. Hope it helps.
May 19th, 2009 at 12:33 pm
I HAVE ACCER TRAVELMATE C300 I have a HP NX9110 that is locked down with a BIOS password. how i can remove passowor howi can enter BOISE PLS HELP ME
June 5th, 2009 at 6:06 pm
http://forums.pcper.com/showthread.php?t=464536
I’m trying to get rid of this bios password on this unknown toshiba satellite laptop. I first unplugged the power connector for 15 seconds. Booted it up and the password stayed. I then unpluged wall power, then unplugged the bios battery connector for 3 minutes. Now the computer won’t boot? The power button doesn’t power it on? Any ideas? Help would be high appreciated.
June 5th, 2009 at 6:18 pm
Chris,
If you have an older Toshiba laptop this parallel plug should clear the BIOS password.
June 10th, 2009 at 5:54 pm
hi i have a lenovo laptop and im trying to remove the bios password and cmos password and i was wondering weather u could help me
June 16th, 2009 at 1:12 pm
I just bought a used HP Compaq NC6400 and it needs to have the CMOS battery replaced. What do I need to do?
June 16th, 2009 at 1:17 pm
Rebekah,
In a HP Compaq nc6400 the CMOS battery is located right under the keyboard, so you’ll have to replace the keyboard as it explained in this guide: How to remove keyboard and replace memory in HP Compaq nc6400 laptop. You can see the CMOS battery on the 5th picture, right above the memory modules.
1. Find and buy a new CMOS battery.
2. Remove laptop keyboard.
3. Unplug the old battery and replace it with a new one.
July 7th, 2009 at 10:58 am
Need to replace the battery on my packard bell easynote F7305 laptop cannot get it out is there a special way to remove it please
July 9th, 2009 at 9:44 pm
have a inspiron 600m laptop and its not keeping the correct year (it is saying 2002). It was keeping the year perfectly before. When I checked the location of where the reserved battery was there was none. I’m a bit confused because the reserved battery (aka CMOS battery) is not there…but the laptop use to keep the year. What must i do? thanx.
July 10th, 2009 at 9:02 am
cb,
Most likely you have bad CMOS battery.
I don’t know why it happens. Maybe you are looking for the CMOS battery in the wrong place?
Install the CMOS battery. Set time and save the settings.
July 15th, 2009 at 12:45 pm
On what i new when system was passworded and accidentally the owner forgot the password by removing the CMOS battery you con retrieve the system back.
but with the introduction of the new laptops am were limited to unblock password,
WHAT SHOULD I DO???????????????????????
July 16th, 2009 at 10:14 pm
Abdul aziz sanin baba,
It worked on some older laptops. Will not work with newer laptops.
Take your laptop to the authorized repair center. It’s not free but most likely they can help (unless it’s an IBM laptop).
July 17th, 2009 at 2:56 pm
Need a Schematic: Toshiba Qosmio F20. Model: PQF20L-00L00H.
Bought while on R&R from Iraq. Went to Thailand! Have had since 7/06 without any problems untill daughter had spilled a coke upon the Keyboard!
Awaiting New Keyboard & CMOS Battery. Plan to Upgrade & could use the schematic!
Thanks,
Bill
July 17th, 2009 at 10:09 pm
billh,
Take a look at this disassembly guide for a Toshiba Qosmio F25. Could be very similar to your Qosmio F20.
July 24th, 2009 at 5:55 am
We were discussing this over at the TechSupport Forums adn this post was pointed out. You mention that the RTC battery isthe CMOS battery – I understand this is not the case in all Laptops – they may have an DTC rechargable and a CAP or Flash Module to act as the CMOS Battery. This is due to the lowering voltages needed by the components on the MB – including the CMOS.
I happen to have an issue i’m attempting to trouble shoot – i noticed the time in the Bios does not keep time. But, not sure it it relates to the CMOS or if it does since i do not know if there is indeed a second soldered component acting as the CMOS battery (CAP or Flash) – my sytem OS keeps the correct time. IS it possible or one of the symptoms of a degrading Lythium RTC battery to cause restore issues or software running issues. My particualr issue is it seemingly starts to slow down to a freeze. After running tests known of my hardware aside from the lythium battery show fault or errors.
With todays comps – adn the possibility of teh dual RTC battery and other CMOS CAP or Flash – what are the symtoms caused by a bad RTC BAttery other than the time being incorrect in the bios? And how do you know if you have the Dual battery/CAP? Most Manufacturors will not give up service manuals which show components soldered to the MB.
July 24th, 2009 at 4:11 pm
plz
can u help me
where is the coms battery in toshiba A100 satllite ??
ana how can i remove it ?
July 25th, 2009 at 9:16 pm
egyptian,
The CMOS battery is soldered to the motherboard. Take a look at this picture (motherboard from Satellite A105). You’ll see the CMOS battery on the right side from the circled screw.
By the way, removing the CMOS battery will not clear the BIOS password. If it’s your reason, don’t even try.
August 19th, 2009 at 5:36 pm
the rtc battery went flat on my acer travelmate 520, and
as well as the date and time being lost, it also did
something to the graphics settings. I put a new battery in
and although the laptop works again, The acer welcome screen
(red satchel)is too big, when the laptop boots up the windows desktop is too big
(can’t see the start menu and systray)
If you hook up an external monitor that’s fine!
when this model was new, it was available with a range of screen sizes from 12.1″(mine)up to 14.1″. it’s almost as if it thinks it’s got the 14.1″ screen attached to it. According to acer
all models run the same motherboard, so how does the laptop “know”
how big its attached screen is?
I’m going slowly mad………
August 19th, 2009 at 8:19 pm
Tank,
Enter the BIOS setup menu and try loading default settings, there should be a button for that. After that save it and reboot the laptop. Not sure if it’s going to help but you can try.
September 12th, 2009 at 6:16 am
hai,,,im facing a big problem…my buffalo network adapter is not working..there is 2 PCMCIA slots in ma laptop..and wen i insert the adapter to the top slot ,laptop detects the network card but after installing the driver ,it says cannot start the device..and wen i insert it to the bottom slot..my xp gets stuck..my xp continues working if i remove the adapter from the slot..what should i do..im not able to use ma wireless these days…i am using IBM T21..
September 13th, 2009 at 10:26 pm
bhagynath,
Not sure what’s going on but it’s possible you have some kind of compatibility issue between the PCMCIA card and your ThinkPad laptop.
I know that ThinkPads might now work properly with some internal Wi-Fi cards because it has to be some kind of “IBM certified card” or something like that. Apparently, the same applies to some external PCMCIA cards.
Can you find another PCMCIA Wi-Fi card for test?
September 18th, 2009 at 9:41 pm
how to delete the bios password?
September 28th, 2009 at 4:23 am
Think Maxdata CMOS battery to M350 Vision model with PhoenixNoteBios under keyboard is hidden in the back under screen hinge. Red & black wiring plus connector can be seen, and by lifting upper casing becomes visible in a spacing. Yet, battery underneath, requiring to lodge the part underneath the screen. The connector can thus be easily disconnected, but battery needs extra operations to gain access to.
September 29th, 2009 at 10:45 pm
Toshiba satellite M40X-148 cmos battery located under hardisk metal housing (the other side of motherboard). need to remove 4 screw tighten the metal housing (actually need to unassembled all parts & screw). it is soldered to the motherboard. need to flip the motherboard. half covered with blue plastic. short using wire the two solder for 15 minute and the bios password is reset. useful when u forgot the password.
October 1st, 2009 at 12:39 pm
ronin,
Have you tried that yourself?
I believe removing the CMOS battery will not clear the BIOS password on newer laptops.
October 16th, 2009 at 8:32 pm
I need to replace a battery that is encased in plastic just like the 3rd example (Dell). Can I buy the battery alone, or do I need to find the entire assembly – enclosed battery +cables+connector?
this is for an acer 9410.
October 17th, 2009 at 6:40 pm
NovaScotiaMika,
I doubt that you can find just the battery alone. I think you’ll have to find and purchase the entire assembly.
October 17th, 2009 at 10:43 pm
i have toshiba tecra a6. my laptop time isn’ running, i’ve checked the BIOS and it’ not running too. maybe i have a problem with cmos battery
do you know where the CMOS battery is?
and how can i remove it?
October 17th, 2009 at 10:51 pm
john,
I believe in a Tecra A6 laptop the CMOS battery is soldered directly to the motherboard. Take a look at this guide for a Satellite M105 notebook. It has same body as Tecra A6.
In the step 22 there is a picture when the top cover is removed. On the bottom of the motherboard there is a square Intel chip. A little bit lower you’ll see the CMOS battery, it’s blue. Same as on 3rd or 6th photo in my post.
October 18th, 2009 at 6:53 am
Hi
I have a Acer Travelmate 4000 ZL1. Is there a guide so I can easily disassemble the laptop so i can get to my CMOS battery. Much appreciated.
Mario
October 18th, 2009 at 6:58 am
Furthermore to my question. Can i use a CMOS battery from a Travelmate 3000 on my 4000?
October 18th, 2009 at 8:46 am
Hi,
I have a Acer Travelmate 4000 LZ1. I would like to know how to disassemble the laptop to get to the CMOS battery. Also would a Travelmate 3000 CMOS work in my Travelmate 4000.
I would like a service manual for a Dell Latitude C540/C64o laptop.
Your help is greatly appreciated.
Mario
October 27th, 2009 at 8:07 am
Mario,
Take a look at this disassembly guide for a Acer TravelMate 3260 laptop, could be similar to your laptop.
By the way, it this model you can access the CMOS battery through the door on the bottom. It’s located close to the wireless card. Take a look at the picture in the step 10, it shows the battery.
I don’t know. Find the battery, remove if from the laptop, find the part number on the battery and google it.
November 3rd, 2009 at 10:41 pm
Toshiba PRO L40
Hi there,
After a bios update computer rebooted fine into windows. I then restarted and went into bios to save settings.
Computer performed reboot but gave black screen syndrome. I think a bios reset is required. The laptop has been stripped to locate the soldered CMOS battery and now I was hoping for information to perform a manual reset.
Thanks in advance.
November 4th, 2009 at 1:59 am
Toshiba PRO L40
Update
I was under the impression that since after WinXP BIOS update, the laptop had initially rebooted, passed BIOS, entered WinXP and after the second reboot and attempted save of BIOS, a simple BIOS reset to default was necessary.
(Summary WINXP_BIOS_UPDATE > REBOOT > WINXP > RESTART > ENTER_BIOS_TO_SAVE_DEFAULT > REBOOT > BLACK_SCREEN)
1.The laptop was dismantled with help from the excellent guide:
http://www.irisvista.com/tech/laptops/Toshiba-Satellite-L45/laptop-disassembly-instructions-1.htm
2. The CMOS battery was located and a small piece of solder was placed across battery wires connected to motherboard and left for fifteen minutes, in order to create a short and therefore force a BIOS default reset.
This was a success.
The BIOS was AMI based.
I hope someone, somewhere finds this information helpful, as it took me a full day to resolve this problem.
Regards.
Thanks.
November 4th, 2009 at 6:05 am
notuagain,
Thank you for your comment. I wasn’t aware that shoring the CMOS battery this way will fix the problem. I’ll try that when I have a chance.
Also, thanks for finding my guide for taking apart a Satellite L45 laptop.
November 4th, 2009 at 8:19 am
Hey there RM, thanks for the sites they sure helped me out!
The battery definitely was drained through the short as ‘LOW CMOS BATTERY’ was displayed in BIOS upon successful boot and BIOS was altered to its default state.
December 22nd, 2009 at 12:12 pm
Hi
Anyone knows were’s located the onboard soldered cmos battery on Texas Intruments EXTENSA 600? It’s a really old laptop from 98…would be great if i could revive it. Dead cmos message on the startup screen.
Thanks
January 3rd, 2010 at 5:59 am
Hi Pedro, the CMOS battery of the Extensa 600 is located behind the Parallel Port Connector. It’s on the front side of the mainboar. You have to completely disassemble the laptop. The battery is NimH 3.6 V /40mAh and is soldered on the mainboard (1cell). It can’t be seen because it’s hidden under the metal frame of the laptop. Basically
on the right of the Display connector … search for the service manual of the Acer Extensa 600 named ‘extensa 600 650.PDF’ for easier disassebmly. Good luck ! … it took us 2 days to find it … finally found it this night … it was a nightmare
January 4th, 2010 at 4:24 pm
HI there Thanks for the info man! I was looking long time the location of it…it’s really hidden hehe
Next week i’ll do it and post results then.
January 15th, 2010 at 12:24 am
Is there a way to reset the bios password on the satellite a215-s5825? ( I do not see this model listed on http://www.insidemylaptop.com/my-toshiba-laptop-displays-password-prompt-on-startup/ ) And i saw mentioned “By the way, as I mentioned in the previous comment, removing the CMOS battery in this model will not help you to clear the BIOS password.”
If removing the battery does not reset it, is there a method i can use to do it? any jumper settings that may get it done? or anything?
thanks in advance
January 15th, 2010 at 11:50 am
Whats the Number of this Bios Battery??
http://www.laptopparts101.com/wp-content/uploads/2008/12/cmos-battery-under-top-cover-560×420.jpg
January 19th, 2010 at 11:29 pm
Michael,
I believe it’s Sanyo ML1220 rechargeable battery. Used in many newer Toshiba laptops.
January 19th, 2010 at 11:38 pm
the lost ranger,
If the BIOS password was set by the laptop, call Toshiba and explain what’s going on. Most likely they will clear the password at no charge.
The password is cleared by shorting two contacts on the motherboard. I cannot tell you more. If it’s your laptop and registered on your name, call Toshiba and most likely they will help you.
January 26th, 2010 at 1:34 pm
Where can i find the Cmos on the compaq presario r3000?
I need to bypass a bios password.
Is there an other backdoor to compaq notebooks other than “compaq”?
Thanx in advance
January 27th, 2010 at 2:36 pm
Lux,
I’m not sure if disconnecting the CMOS battery will help to get rid of the BIOS password. Maybe you can find this info in the service manual for Compaq Presario R3000 notebooks here: http://h10032.www1.hp.com/ctg/Manual/c00212209.pdf
February 22nd, 2010 at 11:31 am
HI,I have a Toshiba Satelite M45 S165 laptop(5 years), and I think I a have a Cmos batery problem. It all started 1 year ago when the time keep falling behind. 2 days ago I took out the main battery, and after that the laptop woudnt start again. If I manage to enter BIOS, the time is freezing after 3 second, and nothing,I have to unplug the AC, and take out the main Batery to shutdown the laptop. I think the problem is the Cmos batery, which is soldered to the MB.
I dont know what tipe is it, and where to buy a new one.
Sr for my eng. Please help me.Tx.
February 22nd, 2010 at 12:03 pm
delu,
I don’t have this motherboard and cannot confirm what CMOS battery it has, but I believe that Panasonic ML1220 might work.
Google for Panasonic ML1220 and you’ll find it. I found this battery on another Toshiba motherboard and it looks similar to one installed in a Satellite M45.
March 8th, 2010 at 6:41 pm
I have the Toshiba Satellite A305 laptop as shown above. Can you short this the battery and how would you go about doing it? If not and I remove the battery will I have to re-solder it?
March 10th, 2010 at 12:35 pm
A common small trap some people are unaware of, some soldered Cmos Batteries run at 1.8V and not the standard 3.3V of a CR2032 this is just one thing to be aware of. So take it to a watch maker as mine was a small brown cell and the shop assistant was able to hand me an exact replica of it.
Sadly good help is like a needle in a haystack and everybody things their a pro. `not getting at anyone on this site btw’
Quote from another site “my laptop does not work it has a blank screen powers up and dies”.
A typical time wasting answer to that is something like “have you tried the recovery disks” it really makes me want to scream when people don’t read the question properly. What possible use are the recovery disks if its CMOS battery or chip has possibly died!
EEprom blower!!!!!!
I will hasen to add that a dead Acer 1800 battery brought me here
March 10th, 2010 at 10:22 pm
MR Blogs,
All motherboards are different.
For example, in most newer Toshiba laptops CMOS batteries run at 3.0V
LOL!
How can you run the recovery disc if the laptop is dead???
By the way, in the above mentioned scenario I would check the AC adapter first and RAM modules after that. It’s possible one of the modules is bad.
March 12th, 2010 at 3:31 pm
I have a Toshiba Satelight L45 Series. It has a soldered CMOS Battery like most Toshibas. This is what my motherboard looks like. The battery is to the top…
http://www.irisvista.com/tech/laptops/Toshiba-Satellite-L45/big/toshiba-satellite-l45-disassembly-17.jpg
Toshiba wants me to replace my entire motherboard. I wont do that because it works perfectly exept for this battery needed replaced.
Does anyone have any clue what battery or what voltage this battery is???
March 12th, 2010 at 3:39 pm
Wes,
Not sure 100% but check out this one:
http://www.pchub.com/uph/laptop/48-25680-8305/Panasonic-ML1220-Cmos-Resume-RTC-Battery.html
Looks like same battery.
March 13th, 2010 at 9:38 pm
Whats the worst thing that can happen if I stick a 3volt battery in a 1.8v socket? I know the trace on the Motherboard can hold alot more than 3 volts. But as far as the bios chip?
I know and heard of toshiba and other companys making “Backup RTC Batterys that you just plug in somewhere on the motherboard”. Not sure where but i dont think it would hurt to put a 3v battery in a 1.8 socket. worse case scenario once it ran for awhile it would never fully charge up because the A/C adapter would only trickle it to a certain voltage. It would be stronger but im sure a bios chip would hold it. I can see 2 volts max hurting anything.
Just for kicks im sure it would remember wierd things like what you ate yesterday and it would be stored in your bios. You would load up windows and it would ask you.
…Press any key to boot from Cheeseburger….. LOL!
March 29th, 2010 at 3:25 pm
Wes,
I don’t know, never tried it myself. I don’t think that a 3 volt battery will damage anything.
April 14th, 2010 at 3:57 pm
Hey
This is coming from a fellow computer repair person. I dont repair to many laptops and I think this is why…
I have here a Compaq 2510c. The Startup/Bootup password is unknown to the user. I used the documentation from https://computinghardware.web.cern.ch/ComputingHardware/DOC/HP/HP-2510p/c01095444.pdf that shows how to fix it on page 39. It says basically to remove batter and then RTC battery for a few minutes and then replace it. I’ve done this very carefully. Now, the screen wont show anything. It seems as though the HDD works fine since all lights are coming up correctly. Any suggestions? I’ve reseated stuff just to double check likely 5 times. Looking for any tips here
April 14th, 2010 at 7:11 pm
nevermind… i see that I did not push the card in good enough… the screen loads now but still not able to get past the fact i dont have a boot password
October 10th, 2010 at 8:03 pm
hi,
first at all, i’m sorry my English not good. i hope u were able to understand me.
my question is:
does anyone know how to find a jumper on motherboard??? because i want clear cmos password in bios.. previously i’ve tried clear cmos password by unplug battery cmos inside motherboad but it’s didn’t work. please help me… i really appreciate with your help. thnks
October 11th, 2010 at 5:56 pm
wan,
Laptop motherboards are different from desktop motherboard. There are no jumpers.
All laptop motherboards are different. On some of them you can clear the password by shorting some hiddent pads. On other motherboards you cannot remove the password at all.
October 12th, 2010 at 4:04 am
Hi, I’m just wondering where I can get the cmos battery shown on the last picture(toshiba a305) if you could give me some info it would be really appreciated. Thanks.
October 12th, 2010 at 4:28 am
Or even if you could let me know the similar model battery I could use would be awesome..Thanks heaps..
October 13th, 2010 at 9:25 am
Antz,
I think something like this might work.
http://tiny.cc/iw2qw
It’s a Panasonic ML1220 Battery Coin.
October 13th, 2010 at 11:51 am
please help!! i live on a fixed income of 602.00 and am trying to go back to school so as to increase my earning potential. my computer has a bios password on it, and i need help removing it. it is an older computer, a hp pavilion ze 4600. please, please help me.
October 13th, 2010 at 7:33 pm
barbara,
I think on some older laptops you can remove the BIOS password by disconnecting the CMOS battery.
I’m not sure 100% if it will work but you can try.
Turn off the laptop, unplug the AC adapter, remove the main battery, disconnect the CMOS battery and wait for about 10 minutes. Press on the power button while all batteries removed and keep it pressed for a seconds.
October 13th, 2010 at 9:03 pm
Thanks Repairman, you are a legend..
October 14th, 2010 at 11:42 am
Hi, any idea where i would find the bios battery on a sony vaio pcg-791m? do i need to completely dismantle the thing?
Kind regards
October 14th, 2010 at 11:49 am
it could be that I meant cmos battery. Its just that the clock stops if the laptop is not on mains power. If i leave for a few weeks then it will refuse to connect to internet unless I system restore and reset time and date !!!!
October 19th, 2010 at 7:01 pm
Hi Repair Man
i have an old compaq evo n600c that has not been used for a while the main battery is dead i only used ac power when working on it.
A few days ago im tried to boot the laptop. Im getting an error message system disk error/non system disk…
So what i did i removed the battery and booted from the ac power.
I received a message 162-system not defined…
So the system downloaded default settings
and prompting me to select F1 saves changes F2 ignore changes
I also see a message CMOS checksum invalid.
the hard is also doing a clicking sound
Any help will be appreciated thank you
thank you in advance
November 10th, 2010 at 8:10 am
My Toshiba L355D is dead – nothing but the DVD spins (no HD action) and screen is blank), This happened after a couple of days of lost time/date. I replaced the CMOS battery and still get the same deadness. Any suggestions?
Thnx, in advance,
Tom
November 14th, 2010 at 12:25 pm
i have a toshiba a215, my laptop turn on but the screen is black its happened after a bios update, the cmos battery is like the last pic so remove the battery will repair my laptop? and how i can remove the battery or reset the bios?
November 15th, 2010 at 8:29 pm
hardx,
If the laptop video failed after updating the BIOS, there is a chance that BIOS got corrupted. If that’s the case, you’ll have to replace the motherboard. I REALLY doubt that removing the CMOS battery will help. By the way, the CMOS battery is soldered to the motherboard.
Here’s what you can try.
Turn off the laptop, disconnect the AC adapter and remove the battery. Wait for a few minutes. Now plug the AC adapter and try tuning it on again.
Also, try reseating memory modules. Just in case.
November 15th, 2010 at 8:33 pm
Tom,
First of all, try reseating memory modules. If you have two modules installed, remove them one by one. It’s possible that one of the modules failed. When you remove the failed module, the laptop should start properly.
November 17th, 2010 at 1:52 am
I was watching a movie yesterday, and my laptop went suddenly hung… I had to pull the battery out to get it to work, then when I put it back on it didn’t come on not even the BIOS, the screen didn’t even light up, could this be CMOS or???
November 17th, 2010 at 11:21 pm
hello
i have a old toshiba tecra te2100 i forgot the bios password. i tryed removing the cmos battery for to dats but no luck i called toshiba and they want me to send it in.$400 bucks to fix he said!! does anyone have any ideas? or can you tell me where the bios chip is located on this type of motherboard?
November 18th, 2010 at 8:36 am
trashman,
It’s not necessary to disassemble the laptop. Try this method: http://www.laptoprepair101.com/laptop/2006/02/10/remove-clear-toshiba-laptop-bios/
It works for most older Toshiba laptops.
November 18th, 2010 at 7:15 pm
THANKS!!!! it worked!!! gotta give it to ya!! You are truly the REPAIR MAN thank again
December 7th, 2010 at 11:16 pm
Tobey,
Could be memory failure.
Do you have two memory modules installed in the laptop? Try removing them one by one and test with each module separately.
Also, I assume it’s not just failed power supply. Right?
December 31st, 2010 at 3:07 pm
hi,
Where can i see my CMOS battery in my ASPIRE AX1800. i forgot my
January 4th, 2011 at 8:53 am
Dar,
This is a desktop PC right? The CMOS battery should be somewhere on the motherboard.
January 6th, 2011 at 12:13 pm
i have a HP laptop that will not even load the BIOS settings do i take out the CMOS battery
January 7th, 2011 at 9:20 pm
Adam,
What HP laptop? What model?
Also, how does it fail? Do you get any LED light when laptop turned on? Is it dead completely? More details please.
January 9th, 2011 at 12:29 am
I have a vaio vgn-s360. When I turn on the power the lights for the indicators (battery, power, system) and the fans turn on but the monitor is blank. So I try plugging in an external monitor and still see nothing. Is this a problem with the cmos battery? What can i do??
January 9th, 2011 at 11:01 am
disassembler,
I don’t think this is CMOS battery related issue. I think the laptop should turn on even if the CMOS battery completely dead. It will not be able to keep current time and date, but should turn on. I think you have another problem.
First, I would check memory modules. It’s possible one of the modules is bad. Try reseating memory. Try removing memory modules one by one and test your laptop with each module separately.
January 13th, 2011 at 6:47 pm
How can I clear the BIOS password in a Toshiba Satellite L505-S5984?
January 14th, 2011 at 2:22 pm
Hello there, any knowledge where i can find bios battery on neo sony empriva nx40 laptop?
January 17th, 2011 at 2:34 am
Sir, my laptop,(compaq presario r3000) starts to shut down before it turns on the screen…the keyboards lights though before it shuts down.. the charger seems okay, but when i used another charger with 19V (the original one is 18.5V) it boots up the screen but then again, it shuts down after 3-5 seconds.. the cycle repeats.. can you please help me? it does not have any batteries since they just gave it to me..my friend says the CMOS batt must be replaced.. some says its the harddrive.. please help me.. repairs in my country is reaaalllly expensive.. help.. thanx so much…
January 28th, 2011 at 4:15 pm
Leonardo,
I’m not sure about this particular model but let me guess…
I many newer Toshiba laptops the CMOS clear pads located in the memory compartment (sometimes you have to remove clear film or sticker).
Usually, these pads look like small engaged gear teeth.
You unplug the AC adapter, remove the battery and short those pads with a screwdriver for about 30 seconds.
After that assemble the laptop and turn it on.
January 28th, 2011 at 4:17 pm
natakilub,
Are you sure the model number is correct? I google your model and didn’t find any laptop.
January 28th, 2011 at 4:42 pm
JohnPercy,
Could be memory failure. Try reseating memory modules.
Do you have two memory modules installed in the laptop? One of them could be bad. Try removing modules one by one and test the laptop with each one separately. When the bad module removed, the laptop should start properly.
January 31st, 2011 at 5:44 am
uhmmm… ill try.. there are two.. the problem is the other one is below the keypad.. so i must open them whole.. i’ll try.. thanx so much!!
February 13th, 2011 at 1:05 pm
Hi
Please can you tell me where the rtc battery is located on the Toshiba Portege P7220?? (exact model pp722e-h390q-en)
Thanks
NLJ
February 15th, 2011 at 8:50 am
Hello,
I have HP Pavillion laptop.
Just two days ago, it stopped working suddenly. I turned on the power button, but the laptop keyboard lights up for 1 sec, then goes off. Same thing with and without battery (only with power adaptor). Is my CMOS bad? what do u think? Thank you very much.
February 16th, 2011 at 11:09 pm
NLJ,
Sorry, I don’t know this model at all.
February 16th, 2011 at 11:12 pm
kusun,
I don’t think this is CMOS battery related problem.
Did you test the AC adapter? It’s possible the adapter is dead and the battery doesn’t have enough charge to start the laptop.
Test voltage on the AC adapter.
February 17th, 2011 at 12:52 am
i have a sony vgn-n35o3 and its asking me for my bios password and i forgot it. i tried unpluging that little battery but it still ask me for the bios password. what could i do?
February 24th, 2011 at 11:38 pm
How can i reset bios password for acer aspire 2920, i’ve tried to find CMOS Battery but i can’t found?
February 25th, 2011 at 12:45 pm
Hi Repair-Man,
I’ve got a bad RTC battery in a Toshiba A215 that is only 3 years old. I have tried charging it, updating the BIOS, all kinds of other possibilities, but to no avail – battery errors keep coming. The next step is to try changing the RTC battery. My friend who is skilled with laptop surgery says he’s willing to try to replace it for me. Any tips for how to deal with the soldered-on battery that this model has? Thanks for your very helpful site! –T
February 28th, 2011 at 7:14 pm
At my office I have a Toshiba Satellite L305-S5955 I never set a password but now i can’t even get into the bios it asks for a password how do I bypass this (if it is taming out the CMOS could you give me a Link to a pic so I can see what it looks like I took the entire thing apart and I don’t see anything that resembles a battery. Toshiba wants more $ to fix it than I paid for it brand new! I will never by another Toshiba this is the 2nd time that it has done this the first time was 3 months after the purchase date!) thank god for factory warranties. What brand would you suggest for my next purchase?
March 2nd, 2011 at 8:25 pm
T,
Just desloder the old battery and solder a new one.
I think this Maxell ML1220 CMOS battery might work.
March 2nd, 2011 at 8:53 pm
Kim,
I’ve seen this problem on more than one Toshiba model. One day it’s just setting the BIOS password on its own. I think it’s faulty BIOS.
You can try this. In the memory compartment search for two pads marked as B500. Short this pads with a screwdriver and turn on the laptop. Keep this pads shorted while the laptop turning on. If it’s successful, the laptop will bypass the password screen. If it doesn’t work, try again until the password erased.
After the BIOS password cleared, update the BIOS to the latest version.
March 7th, 2011 at 12:24 am
Hello repair man i bought this laptop used and did not notice that it needed a boot password i can not load into anything not even to load a windows disc the labtop is Compaq nc6320 ive tried to hard reset the machine (taking the rtc battery out) it does not work, can this be possable because the rtc battry is dead for it not to clear bios
March 18th, 2011 at 2:26 am
hi,
where is the levono ideapad y430 cmos battery located!? i have tried to search the net for it and still not successfull..the only results i get are of sony, hp, compaq etc, but NO LEVONO! Please help
Thank you
March 19th, 2011 at 6:30 am
Please, can some one tell me how I can locate cmos battery for comaq R3000 model R3360US. I have opened the laptop but just could not loacated. I can not access my laptop since it asks me the power on password and i just dont have any idea what it might be. I even can not remeber that I have provided one for my laptop. Please help.
March 29th, 2011 at 9:57 pm
Good day mam,how can I identify the cmos battery code of my neo laptop M541N,co’z I dont have any model of it..thanks and hope that you may provide my query..
May 1st, 2011 at 12:22 pm
How can I clear the bios password in a dell inspiron 8100
service tag # 5nppy01-595b.
June 5th, 2011 at 4:56 am
04 toshiba satellite a25 must disassemble every thing screen harddrive key board i hope i can remmember how too put it back togeter 83 screws out so fare 18 screws to go CMOS/RTC GREAT DESIGHN what a load. seems i could be more execesable tashiba support didnot know where CMOS/RTC WAS REFERD ME OUT SAYS TECH SUPPORT 34.95 PLEASE.DIFFACULT, SAY A PRAYER FOR MY LAPTOP.AT FREE I PAID TOO MUCH. STEVEN
June 18th, 2011 at 4:08 am
Will a Toshiba Satellite laptop operate without the CMOS battery?
August 16th, 2011 at 8:28 pm
I Have A Satellite u505-s2950 (Very Similar Design As In Picture 6)and im wondering if I unsolder the cmos battery will it remove the password or is this one of the laptops that that will not work for.
plz help
August 16th, 2011 at 9:34 pm
@ Corey Perry,
Not sure 100% but I think removing the CMOS battery will not clear BIOS password. Most likely this one is like previous Satellite models – there are two contacts on the motherboard that you have to short with a screwdriver for a few seconds. Usually these contacts look like engaged gear teeth. Maybe you can find these contacts in the memory compartment. Just a guess.
August 31st, 2011 at 6:13 am
Hi, I have a Toshiba Satellite L45-S7409.
What kind of CMOS battery do I need?
every time I turn on my laptop I have to press F1 key to continue and set time after login to windows.
September 7th, 2011 at 12:03 pm
Just wondering if anybody knows the cmos battery needed for HP ZV5460US, SN CND592169H, SN OR471UA #ABA, Motherboard 370493-001, EHR66A1
September 14th, 2011 at 12:34 pm
hi i have Toshiba sattelite A300 I forgot BIOS password how i can remove it
December 15th, 2011 at 11:08 am
@ Basel,
I don’t remember off the top of my head but most likely this laptop has two CMOS pads in the memory compartment. You can find them when both memory modules removed. You short those pads with a screwdriver and it should clear the BIOS password.
Removing the CMOS battery will not clear the password.