e30 si board batteries

[stuart]

all the articles I've read about replacing these batteries
refer to them as being rechargeable.

when I removed the board from the instrument cluster of my
14-year-old 318i, I found two batteries with the description:
Sanyo Laser Lithium CR14250SE (3v).

looking up these on the Sanyo webpage describes them as
primary batteries - i.e. not rechargeable. locally available
replacements here in an electronic shop in munich are
Varta CR1/2AA and stamped on these is the warning:
Risk of fire explosion or burns. Do not recharge.

Well I don't want to blow up my faithful companion of 14 years
especially not as I usually sit about two feet behind the
si-board, so what is the story here?

Are these batteries rechargeable or not?

[Klaus]

"stuart" <de> schrieb im Newsbeitrag
news:bhq88m$i8n$lrz-muenchen.de... 

Stuart,
all the original boards were equipped with those 2 standard
(Mignon?) 1.5 V rechargeable batteries.

They broke down after some years and maybe for that reason the
design of the board was changed.
For replacement boards they use these 2* 3V batteries.
When you buy a new board they are delivered with an open jumper
to avoid battery drainage before it gets installed.

So that means that your board already has already been replaced
some years ago.
That is why you can't find the 'old' 1.5 rechargeable batteries.

Don't know if it helps if you solder in new batteries. Sometimes
it does, but not always.

At this date a new board is EUR 90

best regards,
- Klaus

www.bm24.de

[stuart]

Klaus S wrote: 

thanks, I realised that the board has gone through several revisions
and mine is a MotoMeter just like in www.e30-2.de/fotost/f00393/06.jpg.

but my instruments have been a bit erratic lately (Drehzahlmesser
geht auf Null und dann wieder auf Leerlauf, Verbrauchsanzeige zeigt
nichts, "Inspection" blinkt ab und zu mal) perhaps its just to hot
here recently.

anyway reading around, it seems that erratic behaviour is associated
with bad "Akkus", so I thought I'd check mine.

[Terry]

You should replace the batteries - it only takes a few minutes. De-solder
the batteries, and replace them with rechargeable NiCad batteries from Radio
Shack with the solder leads already attached. I suggest you fully charge
the batteries BEFORE you solder them in place.

Terry


"stuart" <de> wrote in message
news:bhqi3a$ne0$lrz-muenchen.de... 

[stuart]

John Burns wrote: 

thanks, but I'm still confused, if they are just normal non-rechargeable
lithium batteries you can replace them with anything of the same size
and capacity. Why did you need to get Sanyos?

[John]

> thanks, but I'm still confused, if they are just normal non-rechargeable 

There must be two PCBs. One designed for 2x1.2V NICADs and one for 2x3V
Sanyos. You can't put NICADs in the Sanyo style PCB.

--
Who needs a life when you've got Unix? :-)
Email: demon.co.uk, John G.Burns B.Eng, Bonny Scotland
Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html

[Dave]

In article <bhq88m$i8n$lrz-muenchen.de>,
stuart <de> wrote: 

Earlier cars did indeed use Ni-Cads.
 

Later ones Lithium primary cells.
 

They have approximately the same *overall* life as rechargables, so it's
recommended on older cars to replace Ni-Cads with these after disabling
the charger circuit.

--
*A bartender is just a pharmacist with a limited inventory.

Dave Plowman co.uk London SW 12
RIP Acorn

[stuart]

Dave Plowman wrote:
 

thanks a lot, so I deduce from this that
1. my 14-year old board does not charge the batteries because the
Sanyos are primary.
2. the 14-year old Sanyos are probably no longer delivering 3v.
3. this could be the cause of erratic behaviour in the instrument
cluster.
4. I can replace the Sanyos with Varta of the same size and capacity
5. my BMW feels like new again!

[stuart]

John Burns wrote:
 

no what I meant was: why did you order Sanyos specifically, instead of
buying ElCheapo?