Thaddeus

Hi,

I went to start the 951 2 days ago (after the car sat for 2 months) and only got a 'click' for my trouble.

Put the charger on for several hours, the thing is pumping in juice at 5 Amps.

I turned the key to the 'on' position and my ammeter is showing 10 Volts.

Is there a short in my battery? Even if the battery's almost flat, what current is there should be at 12v, should it not? Do I have a bad cell? I suspect the battery may have frozen when it was low...

thanks

Thaddeus

david fracolli

I am assuming you mean the voltmeter is 10 volts? Sounds like you have a bad cell. had the same thing happen to me last winter.

Thaddeus

Yes, the voltmeter. Sorry.

Rats. Now I'm in a bind. I want to be able to start the car and warm it completely up, but to do that I'd need to replace the battery. But that would mean I have to install a new battery and leave it in an idle car for 2 months until the springtime re-emergence. Which would give the new battery a chance to run down, freeze, and so on.

Typical...

Dennis Wilson

A few hours charging at 5 amps is not enough to recharge a completely dead battery. Try some additional charging to see if the voltage increases.

Dennis

IceShark

Thad, as noted you didn't charge nearly long enough at the piddely 5 amps. And don't worry about freezing the battery as it hasn't been nearly cold enough around here this winter to have done that.

Go to this link and you can read all about lead acid batteries and how to bring them back from the dead: <a href="http://www.uuhome.de/william.darden/" target="_blank">http://www.uuhome.de/william.darden/</a>

Operator

anyone know what the cranking amps on a battery for a 944 should be ? 500 ? does it really matter ?

I was looking at that page you linked IceShark and it has all the manufacturers of Batteries listed, like JohnsonControls really makes DuraLast and Motocraft and even the batteries Costco sells so I figure I might as well get a cheap one from costco but they dont have anything "compatible" with a 944 when you do a search on autobatteries.com except for some motorcraft one.. weird.. so I wonder, does it really matter?

IceShark

Porsche wants a 63 amp hour battery in the 944. The cold cranking amps depends on the battery discharge rate and what you can get away with depends on your climate.

People play around with smaller batteries to cut weight down to as little as about 15 lbs, from about 45lbs in stock form, but usually they are in warm climates ... for you in CT in winter you probably want at least 550 CCA to be safe. 650 would be much better.

On replacements you want a BCI Group 40R or Group 41 battery. This designation is a world wide standard that specifies the dimensions and terminal post arrangements. The Group 41 is the same as the 40R except a little longer (0.7 inches) and usually more powerful.

I think most battery manufacturers make these sizes and your searches only showing motorcraft is the result of a crummy program.

You can also stick in a gell battery like Optima but you have to screw around a bit for mounting and the terminal posts are reversed in polarity from stock. You need to buy a side terminal post if you want the stock negative cables to fit easy.

This battery kit project is filling me with all sorts of knowledge I don't really want to know. <img border="0" title="" alt="[Wink]" src="wink.gif" />

944Play

FWIW, my 944 has a group 47 battery, which is slightly taller than 40R or 41. It fits just fine, but it's probably a good idea to have an insulating terminal cap on the positive side.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

P944forScott

FWIW I just got a cheap battery here in So. Cali. from Kragen (our local cheapo chain car parts store) so they should not be too hard to find.

Yeah I was going to buy one of them fancy gel cells, but I am constantly flip floping on weather to sell my 1984 and move up to a new(er) 944 so I went lo-buck.

When you change out the battery make sure you check the tray for rust and repair as needed.

Also if you can jump the car you should get aprox. 13VDC at the terminals if your chargeing system is working.(Iceshark can porbably give you that number out to six decimal points)

Good luck!

IceShark

Yeah, I would be careful about putting in a group 47 battery as the posts stand 0.6 inches higher. It should be OK as the positive is still at the rear so more clearance but if the hood has been removed and not reinstalled exactly the same you might short the positive or dent the hood on the negative.

Why do it unless you are in a pinch of some sort like stranded in the middle of nowhere with a dead battery and that is all that is available?

LOL, Scott. If your system is in good shape you should be seeing almost 14.0 volts at the battery, say 13.9 for most 944s if you don't have much of an electrical load on and haven't done any upgrades to the electrics. If you are down around 13.0 volts at idle you have problems somewhere. A very dead battery could do it though.