(Hopefully) Basic electrical question - United Bimmer Community

**mincemeat** · 11-29-2006, 12:06 AM

As soon as I turn the key to the accessories position, the system voltage plummets and within a minute there would not be enough charge to crank the car.

Visually inspected the battery and I realise it's well and truly dead - a slight bulge on its side.

So, tomorrow I'm doing the obvious and fitting a new battery...

However, what concerns me a little is that my car happen to have a Valeo altenator... what would the symptom of a faulty voltage regulator be? Would it cause a big enough spike to frag a battery like that?

Anyway here are some reference Test #9 voltages:
Running and idle: low 13's
Running and above 1500rpm: 13.7v - 14.1v
Engine off: Don't let it fall below 11v

Any comments would be appreciated, cheers

witeshark · 11-29-2006, 12:10 AM

More like just an old battery

**mullethunter3** · 11-29-2006, 12:17 AM

If that doesn't work, check the amp draw when the car is off. My car did that for a while and it killed a couple batteries. I fixed the problem though.

**c1apton** · 11-29-2006, 04:57 AM

Your alternator ratings are good, like "whitey" said it's just an old battery.

**mincemeat** · 11-30-2006, 04:41 AM

Thanks everyone for theiy comments.

The new battery went in and the guy used an electronic tester to check for drainage, which came out okay.

Now the funny thing was the age of the old battery. They deciphered the manufacturer's build code on it and concluded that it is barely over two years old and just out of warranty... strange.

Maybe I'm just very unlucky with that particular instance of a battery, or ya'll can start taking bets when this one blows up and why

**c1apton** · 11-30-2006, 05:23 AM

There's alot of variables in battery choices. Some places sell you "what fits" (physical size) other places sell what's made to operate in specific vehicles. You might have had a lower end version. A good rule of thumb - if you can afford it, buy the highest # of cold cranking amps. Don't skimp on battery quality for a couple of $$$ difference. Too many folks buy the least expensive and expect long life. The key here is to SHOP - $$$ vs CCAs.
IE: I shopped for my E34 and found one at Autozone that was 1000 CCAs and was only 69.95 where the "Die Hard" top end was $109 for 600 CCAs - so shop for your best value & buy from reputable sources.

**RSF5** · 11-30-2006, 09:48 AM

^^ Yep, always look for quality overall if you want long life.