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Flat battery every 2 weeks!!!

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I recently bought a 1991 944 s2

Since purchasing it the battery has run flat 4 times and the alarms keep going off

The AA have checked it and the alternator appeas to be working putting out about 13.5 amps while running

Is there anything I can do to stop the power loss?

Also does anyone know if I can trickle charge the battery while it is still in the car or do I have to remove it every time?

Will a regular (every 2 weeks) battery removal begin to damage the electrics / engine mgt system all?

The Post has an advert for some called an accumate - does anyone know if this will help?

Hope someone can help

Thanks


 
I bought a battery charger that fits into the cigarette lighter. Brilliant and no more flat battery. You may have to have a slight alteration to the wiring, but its worth it.
Harriet
 
hi
I bought an (Accumate) battery charger / conditioner. These conditioners are inteligent and keep the battery fully charged.... but will not overcharge. Bought mine off eBay (buy it now) at £35.
I use it on my S2 and have the battery terminals fixed... with the snap in connector leading to the charger on the wall.

absolutely brilliant .... i would not now be without it.

Paul
 
Have the same as above on mine (except it's called an Oxford Maximiser) - advantage is you can shut and lock the boot as the cable is thin enough to fit under the seal without any bother.
 
Are you using the car regularly because if you are it sounds like you have something draining the battery somewhere. A good test is to put a meter on the batteryand check the amp drain. Remove the fuses one by one until you find the one casuing the drain.

If you are not using the car regularly then yes get a battery conditioner. I have the carcoon from www.carcoon.co.uk and it just plugs into some clips on teh battery if I know I'm not driving it for a while
 
Paul

I only use the car once every 10days-2 weeks for maybe 30mins and have a fairly hefty alarm for insurance purposes

Is this what you consider light use?
 
what alarm did you have fitted? I know I had problems with my Porsche alarm until I flicked the switch on the siren.

Although an optimate may solve the problem short term, Iy may be easier to find what's causing the drain aswell. If the battery is getting that much constant use, it's not gonna do it any good.
 
ORIGINAL: millisland

I bought a battery charger that fits into the cigarette lighter. Brilliant and no more flat battery. You may have to have a slight alteration to the wiring, but its worth it.
Harriet
Click to expand...

Don't understand![&o]
Your battery charges your battery?
 
ORIGINAL: flamingeye

Don't understand![&o]
Your battery charges your battery?
Click to expand...

The cigarette lighter is a hot lead at all times so she plugs the charger into it and that is how the trickle charge makes it back to the battery.

Back to the original problem. 30 minutes drive every 2 weeks will never bring the battery up to full charge, never. So you are starting out with a less than fully charged battery. Then you throw in the probable heavy side draw from this after market alarm. Could be something else also.

So, do an amp draw test with the car at rest and the alarm on and see what you draw. Stock cars draw around 0.050 to a high side of 0.075 amps at rest for reference. So you should be able to let the car stand with the radio memory, car alarm, etc. for around 5 to 8 weeks without a problem.

Better sort it out as the battery isn't going to last long the way you keep knocking it dead. If the alarm really does draw that much and it is within manufacturers specs then I would go with the way Helen does it as it is so much less fuss and muss.
 
ORIGINAL: IceShark



The cigarette lighter is a hot lead at all times so she plugs the charger into it and that is how the trickle charge makes it back to the battery.
Click to expand...
Thanks
I want one, where do you get it?
 
They are a very common item in the States and you can pick them up at any old auto parts store. Like noted above get the smart type that varies the charge depending on battery state of charge so you don't overcharge.

Get on the telephone and start calling your local stores.
 
My charger is a Porsche Auto-O-Mat. I got it from my local OPC and also bought one for Tony's 944. I believe that Autofarm may do them also.

My problem was that being a concours car, I was very sparing as to when I took it out and therefore leaving it locked and with an alarm running, the battery went flat. On one occasion with the battery out of commission, we could not open the back window to get at the battery and I had to squeeze through to the back and somehow get to the battery that way, no fun............... or perhaps it was fun for Tony watching me struggle!!

Since buying my charger some perhaps 5 years ago, my battery has never failed. It is so easy, I just plug it in to the cigar socket, shut the door as the cable is very thin, lock the car and leave until I want to use again. A little red light comes on the charger and I know all is working as it should.

I did investigate chargers that go on to the battery itself but that is a lot more fiddle.

Hope this helps.
Harriet
 
Stating the obvious - how old is your battery, have you tried one off another car? Are you mainly using it in the cold and dark on short journeys? I know you must have thought of that but nobody has posted it. So I thought I would.
 
I had this issue a couple of times on the 944, despite the fact that my battery 'seemed' absolutely fine. I bought a new battery and it hasn't happened again. The old 944 battery (which was otherwise absolutely spot-on) was put in the 924 to replace the puny Halfords battery that was in there and has caused no problems at all in that car regardless of the time left standing (presumably it needs a lot less juice to get going).
 
So, do an amp draw test with the car at rest and the alarm on and see what you draw. Stock cars draw around 0.050 to a high side of 0.075 amps at rest for reference.
Click to expand...
I have done this test and the draw was 0.18 amps and 0.11 amps with the clock, radio and alarm disconnected.
I then removed all the fuses in both boxes (square dash) and the figure did not drop.

Are there any hidden fuses?

All suggestions welcome.

Mike
 
ORIGINAL: berg944

I have done this test and the draw was 0.18 amps and 0.11 amps with the clock, radio and alarm disconnected.
I then removed all the fuses in both boxes (square dash) and the figure did not drop.

Are there any hidden fuses?
Click to expand...

I'm not very familiar with the pre-85.5 cars but with those draws you are going to be lucky to last 2 weeks before you are dead.

I'm pretty sure there are at least 2 fuse strips, however, the thing to do would be to go and get a copy of the electrical diagram from the factory repair manual and look that over.
 
Halfords top of the range charger has a maintain mode and only costs £30. I have no problem fitting the power cable between the rubber seal and the tailgate and closing it fully.
 
ORIGINAL: millisland
My problem was that being a concours car, I was very sparing as to when I took it out and therefore leaving it locked and with an alarm running, the battery went flat. On one occasion with the battery out of commission, we could not open the back window to get at the battery and I had to squeeze through to the back and somehow get to the battery that way, no fun............... or perhaps it was fun for Tony watching me struggle!!
Click to expand...


Not wishing to spoil Tony's fun but should it happen again, on late cars with the electric boot release only (earlier cars the key lock pulled a cable rather than operating a switch) there is a terminal under the bonnet - usually with a blue plastic threaded cover - below the windscreen near the vacuum resovoir (black plastic can sized thingy) that allows you to conect a jump lead to give you power to open the boot.

Another Tony
 
Thank you Tony, I will remember this and I will put a copy of your answer in my handbook. I have, however, already spoiled Tony's fun by buying the battery charger as described in my first answer to this post.
Harriet
 
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