BJJones

Hi

I wonder if anyone can help me with an electrical issue on my 1987 930 Turbo.

My battery keeps loosing charge, I charge the battery and within two days it is flat again.

I connected a meter to the positve side of the battery and the disconnected earth lead, with the meter set to m-amps the meter shows a drain starting at 24 and slowly couting down.

I am f**ked if I know what this means, if anything?

I suppose my battery may just be stuffed but I am loath to drive the car to get it tested when the car has a strating problem.

Any input on if the drain I am measuring means anything or any likely areas that might be causing the drain would be greatly appreciated.

BJJones

I don't seem to do so well on this forum for replies!

So I will add a bit more info......................

I charged the battery last night and the car started first time, so I have disconnected the battery again.

I will re-connect the battery in two days and see if it starts, my logic is that if it does I know I have a battery drain and if it doesnt then the battery is stuffed.

What do you guys think?

art

On my '86 944, I learned from a fellow rennlister that if the door contacts are corroded and do not turn off the circuits that allows the power wndows, etc. to operate after the car is shut off, these circuits will always be left on and will drain the battery.

I cleaned the contacts and no more problems! I have no idea if 911s operate as 944s do, but take a look at your door contacts, or note if the operation of your inside lights is normal. This was my tipoff. The lights did not usually come on when the door was opened.

BJJones

The passanger door has an issue with the switch, I will have a look.

Thanks

Barry

rbcsaver

BJ,
How old is the battery?
Regards,
Steve

ron mcatee

Take it to a battery shop or Porsche shop where they can check out the battery and charging system. You may have a cell going bad in the battery. That's what my problem was.

BJJones

I charged the battery for a day and a night, it didn't seem right as it was totaly flat but the charging needle only showed a decent charge going in for a very short time then it dropped to nothing.

Anyway I re-connected the battery and started the car, knocked it off, disconnected it and left it for two days like that.

I re-connected it last night and the car wouldn't turn over, just clicked totally flat.

So I am in the mind that my battery is indeed stuffed.

redidrum

BJ,

I would check the Overhead and any other Interior lights for grounding out to the metal. Pop them out with a screwdriver and disconnect them. My last few Porsches have had the same problem. I cleared them of the ceiling metal and wrapped them in electrical tape. They aren't insulated well.

Then as mentioned, remove the door switches entirely.

Mr. Obvious advise is new Battery if those fail.

One thing at a time usually works for me.

Good Luck,

Ron

jet911

First step, as Spider911 stated, is to take the battery to a battery retailer or a parts shop and have them test the battery to see if cell(s) are going bad. We have auto-zone, checker, etc. auto parts stores here in the states that will perform this service for free. Everytime I have a problem with a battery holding a charge (with any vehicle), it has played out that the battery was bad or going bad. A new battery always solved the problem. Maybe Loren will chime in :-)

Good luck!

emac

Again -- how old is the battery??

Lorenfb

There're three possibilities:

1. bad battery
2. weak/bad alternator
3. excessive current drain

The #1 can be determined by having a test performed (as mentioned by others)
or leaving the battery disconnected for a few days (3-4) & then reconnecting
it and trying to starting the car. The #2 can be checked using the voltmeter
after starting the car. The voltage should be >14 but <15 volts while having the
engine run. The #3 can be checked by placing your meter on milliamps & placing
one lead on center of the negative post (no battery disconnections yet). Then
placing the other lead on ground. Now slowly remove the negative lead, while
still holding the meter lead on its' post, and measure the "draw" current. Obviously,
ALL accessories must be off including the hood (bonnet) light. The max current
draw should be less than .10 amps (100ma), ideally <50ma.

Note: The #3 test is done as suggested versus just removing the
battery leads and connecting a meter to prevent current surges
to the meter and to eliminate large startup current "hangups"
from electronics because of the meter circuitry.

BJJones

Loren, thanks already done the disconnect and reconnect battery thing as in my post above so I am confident the battery is at fault.

The alternator is fine I have had a voltmeter accross it.

I am interested however in your suggestions for the current draw test and will try that tonight.

Emac, no idea on battery age as it was in the car when I bought it and has no visible dates. The car is very low miles and I understand that this is not good for batteries to I am going to buy a new one just to be sure.

Any suggestions on type, shall I try one of these dry cell ones?

Thanks all for your feedback.

Lorenfb

Avoid using those "monster' batteries, the long ones that barely fit, as they can damage the
Paris-Rhone alternator if the battery is very low and the engine is revved after starting.

The Paris-Rhone alt. output voltage is set at 14.6-14.8 which results in large
charging currents with monster batteries which don't "like" to charge above
13.8-14.2.

Remember: Car alternators are voltage sources which can supply virtually an unlimited amount
of current until they self-destruct, not like the old generators which had regulators which limited
the currents.

Bigger is NOT always better!

rbcsaver

BJJones,
I strongly suspect it is the battery since it's history is apparently susspect to you. (Age and "it was in the car") To get good and susinct help on any forum it is always good to post as much info as you can in your first post. How long have you had the car? Your usage since new to you, do you use a trickle charger (recommended), poles newly cleaned and tight?, etc. How often is the car driven,
daily monthly sits for months at a time etc. All important clues to help you.
First, I suspect that it is the battery. Your 911 is an 87, so the battery is at a maximum of 7 or 8 years old, if it is the original. You say the car is "low" mileage, read as not driven often.
Loren is correct in that "bigger" batteries are not neccessarily the best. But he does not tell you what is important. The battery "group" is the correct physical size for your car. The R in a group size means the poles are located in reverse positions. More expensive is not neccesssrily better either, but "cheap" is probably not a goood idea either.
If you live in a cold climate, then Cold Cranking CCA is critical for good cranking ability. It's the number of amps a battery can support for 30 seconds at a temperature of 0 degrees F until the battery voltage drops to unusable levels. A 12V battery with a rating of 600 CCA means the battery will provide 600 amps for 30 seconds at 0 degrees before the voltage falls to 7.20 V (six cells)
You may want a deep cycle battery. See the following link for info on how to buy a battery.
http://www.uuhome.de/william.darden/carfaq.htm

regards,
Steve

DGaunt

I suggest the Optima line for the reasons listed in the other battery thread.