help! laptop's CMOS battery is dying

[ziliath]

Hi all,

My CMOS battery -- also called the Backup Battery
or the RTF battery -- is dying. When I power up my
Thinkpad I will occassionally get error codes
indicating that the battery is not present or
that the CMOS has been erased.

Today at one point when I tried to power up the computer
didn't even respond--despite the NiMH battery being good--
until I plugging in the AC power.

So I've been shopping for a replacement for this
specific CMOS battery (FRU 12J1695) but I am finding
few places that have the original.

Thus I have 3 questions:

1. I found a battery store locally (first one
I've ever seen) and they claim they can make a
new CMOS battery for $10 that will be compatible.
How likely is that? IBM's manual says using
any part but theirs may cause an explosion.

2. I found a store online that claims to sell
a compatible battery. Another (Index Computer...
that name sounds familiar in a bad way)
claims to have the original, but doesn't
say it's new. Anybody know of a reliable online
store for these batteries?

3. I am aware that Lithium batteries will
explode if (A) they are shorted, or (B)
they are charged. But would putting in a
slightly incompatible battery cause this?
For instance suppose they get the voltage
wrong at the local store?

Thanks for any help.

 

[news.new]

Yes, that is right. the battery is acutally just a "coin" type 2032 battery.
It is safe to use.

 

[Michael A. Covington]

So I've been shopping for a replacement for this
specific CMOS battery (FRU 12J1695) but I am finding
few places that have the original.

You don't have to buy it from IBM. Any sufficiently compact NiCd battery of
the right voltage will do.

1. I found a battery store locally (first one
I've ever seen) and they claim they can make a
new CMOS battery for $10 that will be compatible.
How likely is that? IBM's manual says using
any part but theirs may cause an explosion.

IBM's manual is trying to alarm you. IBM does not even manufacture the
original themselves, probably. Any electrically equivalent battery will
work just as well and just as safely. Explosions (bursting batteries) would
result from connecting it the other way around or possibly using the wrong
voltage or something else that is wildly off.

2. I found a store online that claims to sell
a compatible battery. Another (Index Computer...
that name sounds familiar in a bad way)
claims to have the original, but doesn't
say it's new. Anybody know of a reliable online
store for these batteries?
batteriesplus.com

3. I am aware that Lithium batteries will
explode if (A) they are shorted, or (B)
they are charged. But would putting in a
slightly incompatible battery cause this?
For instance suppose they get the voltage
wrong at the local store?

By "explode" they mean the battery itself would get hot and slowly burst its
seams. (Don't imagine mushroom clouds or windows blowing out!) If the
store connects it backward, they'll probably damage your motherboard
electrically, which is a more serious concern. But they're unlikely to do
that. If we tried to avoid every possible hazard we'd never repair
*anything*!

 

[Michael A. Covington]

In what I wrote, I was assuming it's a NiCd battery. If it's a lithium
"coin cell" then everything is even easier... the battery store should have
no problem at all.

(Not, however, the watch section of the local Wal-Mart. I caught them using
metal tweezers to hold the coin cells... short-circuiting the cell through
the metal tweezers... and wondering why many of the cells were dead by the
time they got them in the watch!)

 

[ziliath]

batteriesplus.com

I stopped by my local battery store, which turned out to be
Batteries Plus itself, and they manufactured a new CMOS battery
on the spot using my original's cable. They had a little welder
machine there so they didn't even solder it. The new battery
so far is working great.
Thanks.

 

[Boris Mohar]

I paid $10 at the local computer shop because I was in a rush. You can get
CR2032 from Digikey for $0.53 ea. P189-ND

I did nor want to lose my setting so I changed the battery with the computer
running. Double sided foam tape on the end of a felt marker held batteries
during the transplant.

 

[hemyd]

What's the product type and model of your Thinkpad? What is it - R31, T30,
T20, etc.?

Henry

 

[Barry Watzman]

Your advice is incomplete and potentially dangerous.

You are correct that a replacement battery need not come from IBM, and
that it can be fabricated from generic parts.

However, some laptops use rechargeable batteries (based on any of 3 very
different chemistries), while some others use non-rechargeable lithium
batteries in a "long life" (3 to 10 years) configuration.

If you try to recharge a non-rechargeable lithium battery, it can indeed
explode with enough force to cause injury or death to the user. Lithium
batteries are not to be taken lightly, they have killed people and
caused the loss of limbs.

So, while the gist of your post is correct, it is absolutely critical
that, before trying to fabricate a non-IBM solution, the user finds out
exactly what kind of battery they are dealing with, and that the
solution be compatible with the existing battery and the laptop CMOS
battery circuit.

[Note, attempting to solder to a lithium battery is another way to cause
them to explode violently.]

 

[ziliath]

I paid $10 at the local computer shop because I was in a rush. You can get
CR2032 from Digikey for $0.53 ea. P189-ND

I was told by the guy at Batteries Plus that you have to spot weld
the wires to the battery because soldering gets the battery too hot.
My Thinkpad 560x didn't have a battery holder included.

 

[Don Bruder]

I was told by the guy at Batteries Plus that you have to spot weld
the wires to the battery because soldering gets the battery too hot.
My Thinkpad 560x didn't have a battery holder included.

Screw that... Just install a battery holder for the darn thing so you
can swap it easily next time it dies.

 

[Barry Watzman]

Well, for once the guy was right and not giving you a line. A CR2032 is
a lithium battery, and trying to solder to them can result in a
surprisingly violent explosion. It won't, always, but it definitel can;
lithium is a metal, but melts at a temperature of 180 degress C (about
390 F). Basically, if you melt the lithium, you get the explosion. A
soldering iron tip is about 550 to 800 F, but you won't get a battery
being soldered anywhere near that hot on it's inside. On the other
hand, however, you can't melt solder unless you get the solder and the
outer case of the battery up to about 190 C (the exact temp depends on
the alloy composition of the solder). So the possibility of an
explosion is very real. The devices that weld tabs do so without
heating anything but a spot on the surface of the battery past the
necessary temperature.

 

[Barry Watzman]

That's good advice IF there is room, but inside a laptop, there often isn't.