View Full Version : bios battery replacements

February 2nd, 2012, 07:57 AM
Today i thought i'd go thrue a few of my old computers and look on how the battery looks and some are leaking others not charging and that stuff, the leaking ones i'd like to change but the question is how, most of them look like a small barrel and are soldered on the mobo itself.

Are there any way to switch these batteries to say a normal 2032 battery like most comps of today use or is that a bad idea.
Was thinking i'd solder some wires to one of those batteries and attach them to the mobo if that is even possible.

February 2nd, 2012, 08:03 AM
i've found the pins on the holders of the 2032 batteries often match the holes the battery goes into, when you solder, watch which side is plus and minus, also alot of older boards have a 4 pin connecter usually next or near the battery that allows for an external battery. For those you can use an old rechargeable phone battery

DOS lives on!!
February 2nd, 2012, 08:08 AM
This thread has some advice. On your battery, are there two pins coming from the motherboard and connected to the battery.

February 2nd, 2012, 08:26 AM
One thing not mentioned explicitly is to determine if the battery you're replacing is a rechargeable one. Simply replacing a 3.6V NiCd with a 3.6V Lithium will lead to grief--lithium primary cells aren't rechargeable and react badly (boom!) if you try to charge them.

You can employ a blocking diode if you want to make that substitution, to prevent the motherboard from trying to charge a lithium.

Most clock chips will work just fine down to about 2.5V, so a 3.6V lithium with a Schottky diode in series leaves plenty of margin for discharge.

February 2nd, 2012, 02:09 PM
Well i have this samsung spc3000v that had a leaking soldered battery and no battery pinns, i broke off the battery, the minus pin went completely off right down to the mobo but the + leg was left behind heh but as theres not much stuff around that place i don't think it will be a problem to replace when i find one.

Are NiMh rechargeable batteries usable for this you think? they seem to be the same size also the same voltage.

February 2nd, 2012, 02:16 PM
Generally, yes, you can use NiMH batteries where you use NiCd. In this application, I doubt that there will be any particular advantage, other than RoHS because both will self-discharge faster than the clock circuit will discharge them.

If this is a system that you're going to leave unpowered for months, you may want to consider a lithium battery.

February 3rd, 2012, 05:51 AM
Is it possible that some of the barrel-type batteries were not rechargeable? So far I've seen two "types" of such batteries - some (usually green) show heavy leakage and I always replaced them with coin-like holders with lithium CR2032s (none exploded so far, they don't even get warm), while the others (usually blue) are very clean, have "RECHARGE" engraved on one end and still seem to hold BIOS information at least over a few days...

February 3rd, 2012, 08:26 AM
Absolutely. They came in both flavors.

February 3rd, 2012, 09:52 AM
well i've ripped out 2 that i've found so far and they are blue and very leaky, glad it didn't damage my samsung 8088.
just wonder how i should go about that one when it doens't have battery pinns if i go the lithium way.

February 6th, 2012, 10:16 AM
okay i can't seem to wrap my head around this battery issue, as i'm typing i've found 5 computers with leaking nicd batteries and i honestly don't know what to do except removing these batteries and if i even should add new ones, i proberly won't use these computers much except for a very few for tests.
the easiest would proberly just be to replace these batteries with a similair one note most of these computers don't have any battery pinns.

i'm trying to figure out the cheapest way to do this, either new similair batteries or maybe some lithium type i really don't know and it's starting to give me a headacke.

February 6th, 2012, 10:31 AM
Since most of the NiCd batteries are 3.6V, you could replace them with direct replacements (http://www.ebay.com/itm/1x-Ni-Cd-60mAh-3-6V-14h-6mA-Rechargable-Battery-Cells-/180800544812?pt=US_Batteries&hash=item2a188d602c) or even use an inexpensive cordless phone pack (http://www.ebay.com/itm/3-6V-800mAh-AAA-BT909-BT-909-Phone-Rechargeable-NI-MH-Battery-AKKU-BATTERIE-/300601741303?pt=LH_DefaultDomain_0&hash=item45fd428ff7) and wire it in, putting the pack itself wherever there's room.

February 6th, 2012, 10:46 AM
i can't find any nicd batteries anywhere i've looked only nimh and it's a shop 70km away but they cost 2.95 euros a piece :|

wondering if it just would be easier to just get som cr2032 coin batteries and add wires to them and then to the mobo...

February 6th, 2012, 11:13 AM
If you're replacing an NiCd, you'll need to add a blocking diode to avoid charging the lithium cell. A silicon diode drops between 0.6-0.7 volts. Since a CR2032 is 3.0V, you'd need 2 with a diode to replace a 3.6V NiCd.

This might be another option (http://viewitem.eim.ebay.fi/VARTA-MEMPAC-3V15H-36V-15MA-BACK-UP-BATTERY-fd1c4/290549748924/item).

It seems that most of the battery suppliers on ebay.fi are in the UK. Very strange...

Do you plan to visit Russia anytime soon? ebay.ru has some nice prices.

February 6th, 2012, 11:20 AM
Well ebay is out of the question, i almost never buy stuff online except some computer stuff from pc shops thats the extent of that and no no trips on the horrison besides that i don't travel, longest i've ever been is to sweden and that's many years ago when i was in school.

Oh i think i know why that ebay is in the uk, that's cause there is no ebay in this country.

Also i don't have any way to shop online as i don't own a creditcard :P

February 6th, 2012, 03:13 PM
Don't you have 'dollar' (euro?) stores that sell cordless phone battery packs?

February 6th, 2012, 03:18 PM
Not that i know of.

February 6th, 2012, 03:21 PM
Not that i know of.so where do you buy your batteries?

February 6th, 2012, 03:26 PM
A litle here and there dependent on what i need, normal batteries (AA, AAA) are almost everywhere but barrel batteries are almost nowhere, mobile phone batteries in a city like 40km away, but cheap batteries... that you can pretty much forget...
Some like the CR2032 can be found in a small store in the next city.

February 6th, 2012, 03:34 PM
Well, in that case, I'd go with a 3-AA-cell battery holder and a blocking diode. 3 alkaline cells will give you about 4.5 volts, with the blocking diode, you get 3.8V, close enough for this kind of thing. So you have to acquire a diode (any inexpensive silicon rectifier, such as 1N4001 will do; the battery holder and 3 AA cells.

February 6th, 2012, 03:55 PM
...mobile phone batteries in a city like 40km away, but cheap batteries... that you can pretty much forget...In case there's a language misunderstanding about "mobile phone", we're talking about a battery pack like the ones below for cordless phones (the kind you use in the house) and not cell phones (like you use in your car and build at Nokia). Here in North America you can buy those pretty well everywhere for one or two dollars, whereas cell phone batteries are much more expensive.


February 6th, 2012, 03:57 PM
None i know even use cordless phones, so packs like that aren't too common around here either, atleast i've not seen any when looking for other batteries.

But i bet those cost more than the nimh batteries i found on a site anyway...

February 6th, 2012, 04:29 PM
In case there's a language misunderstanding about "mobile phone", we're talking about a battery pack like the ones below for cordless phones (the kind you use in the house) and not cell phones (like you use in your car and build at Nokia). Here in North America you can buy those pretty well everywhere for one or two dollars, whereas cell phone batteries are much more expensive.

Mike, this is Finland! Nobody uses a landline anymore--they've all got Nokia mobiles! (Probably even in Lapland)

February 7th, 2012, 06:12 AM
Thats wrong chuck, land lines are used all the time however many use mostly mobile phones these days but the lines are used for adsl for instance, i however have managed to get rid of that line and get a fiber optic connection :)

February 7th, 2012, 08:55 AM
I was joking, Elvi. Nokia seems so ubiquitous in Finland that one might get the idea that nobody uses a land land. As for fiber optic, I'm envious.

Do you have hobby shops anywhere near you? I was thinking that rechargeable battery packs are also common with radio-controlled toys.

February 7th, 2012, 11:14 AM
I'll have to look into that but i don't remember any and i just looked at these packs on the same site i found the nimh's and the packs cost more :/

February 8th, 2012, 10:36 AM
I wonder if this one could work for my tandon with a 2pin battery plug? http://www.vekoy.com/product_info.php?products_id=8144&language=en

And this one for the rest that needs batteries... http://www.vekoy.com/product_info.php?products_id=10010&language=en

Edit: you got to be kidding me, the tandon seems to have a lithium battery in it at 3.6v and it's name is lithium er6 so it seems to be a maxell battery acroding to google at 2000mAH sigh... this makes it harder to understand.

February 8th, 2012, 10:51 AM
If you're replacing rechargeables, yes both should work.

February 8th, 2012, 11:03 AM
But what do you say to my edit chuck? i thought it was a rechargable one and now when i took it loose it says "don't recharche" and i know the battery pinns on the tandon gives a 4.5v charge.

February 8th, 2012, 11:26 AM
Okay, you have a lithium cell in the Tandon. So any non-rechargeable combination of cells should do. You could replace it with any capacity 3.6V (or 4.5V) cell, although lithium will last longest, but alkaline will also work. The current draw on these things is very small, so batteries tend to last their shelf life.

February 8th, 2012, 11:47 AM
I'm a litle worrid of using non rechargeable ones on those 2 pinns, just mesured with a volt meter on the pinns and it was showing 4.8V without the dead battery there.

I do have 4 rechargeable AA batteries but they are only 1.2V a piece so i'd have to use 3 of them to get the right or enough volts, tho these are 2600mAh a piece so maybe a litle large.
Also just tried with 2 lithium AAA batteries making a litle over 3V so that works.

February 9th, 2012, 10:12 AM
Just a litle update, i think the tandon knows if it's a recharge battery or not, here's what i did: pluged in 2 AAA to the mobo and turned the pc on.
Mesured the voltages on the battery pinns with the batteries attached: 3.1V.
Unplugged the batteries with the pc running and mesured the pinns on the mobo: 4.8V.
Reattached the batteries to the pinns and remesured, back down to 3.1V so it seems this solution works atleast for the tandon :)

February 9th, 2012, 11:21 AM
Well no, your battery is simply acting as a current sink for the charging current. Still, it may not matter if the charging current is small enough. Operate the system for a few hours and then check to see if your AAA cells are warm to the touch. If so, you're probably in a dangerous situation--the battery could build up internal heat and rupture. Why not simply replace them with off-the shelf AAA rechargeable batteries?


February 9th, 2012, 11:54 AM
uh well now i don't understand you att all, the old battery was a lithium 3.6v, a non rechargebale battery so why wouldn't this work?

February 9th, 2012, 11:59 AM
Sorry, with all your machines, I'm getting confused. You should be fine the way you are.

February 9th, 2012, 12:09 PM
Thanks i was getting worried there for a sec.
Just to clarify, the lithium battery was inside the tandon tm7516 and is marked with "maxell super lithium er6 (aa) 3.6v"
Heres a picture of one http://www.ebay.com/itm/2X-MAXELL-AA-14500-ER6C-3-6V-Lithium-Battery-W-tabs-/320541321687?pt=US_Batteries&hash=item4aa1c069d7, couldn't find an exact match but it's similair.

February 10th, 2012, 05:12 PM
And... battery replacements done, more or less.
Noticed i had another 386 with a dead battery but it's not leaking and is a lithium so changing that is as easy as changing for the tandon that had the maxell battery.

February 12th, 2012, 07:14 AM
The cr2032 works fine for some applications replacing a 3.6v battery that is rechargable or not. It's used quite a lot (WITH diode) to replace Amiga 4000 batteries (which I am going to do one day to my working 4000).

I replaced the TL-5186 in my R4000 SGI Iris Indigo with a remote holder with cr2032. I'd be happy if it just lasted for a few years.