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| Battery problems https://forums.tipec.net/viewtopic.php?f=25&t=5869 |
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| Author: | rav [ Mon Sep 07, 2009 7:18 pm ] |
| Post subject: | Battery problems |
Had some good fun driving the 944 turbo over the weekend. Even went to Porche and Polo (PCGB event) near Oxford at the weekend. Ive noticed that the voltmeter on the dash shows no more than 12v at any time. Even under driving conditions. On Sunday the car refused to start, i had to embarrisngly jump start it from my wifes car. I measured the voltage across the battery - about 12.3v. I placed a charger across the battery for about 4 hours and re-measured and it shows 12.9v. Any ideas how i can be sure if its the battery or could it be the alternator? |
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| Author: | Brett928S2 [ Mon Sep 07, 2009 7:28 pm ] |
| Post subject: | Re: Battery problems |
Hi  Measure the voltage at the battery with the engine RUNNING... IF the alternator is working properly it SHOULD read 13.9 volts.... Then turn on EVERYTHING electrical you can think of.....and read again but get someone to hold the throttle at 2000 revs....it should STILL read 13.9... Let us know the readings here for more advice on whats wrong... All the best Brett
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| Author: | jameso [ Mon Sep 07, 2009 7:47 pm ] |
| Post subject: | Re: Battery problems |
As Brett said a 12v battery needs above 13.6v to charge although a faulty battery can pull the charge voltage down, most garages should be able to test a battery for you. Depending on your charger it probably needs more than 4 hours to fully charge the battery. |
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| Author: | albi [ Mon Sep 07, 2009 10:33 pm ] |
| Post subject: | Re: Battery problems |
september/october is always the time that a poor battery will get found out. my new one will be here tomorrow  after a jump start tho, it did show almost 14v on the dash. same with a volt metre across the battery when engine is running. on sat i took it for a long run (after jump start) after which the engine turned over really quick, then on sun am it turned really slow and only just about enough to fire it up so a neww batt to be fitted tomorrow.i would get the alternator checked in your case, even with a dead battery your gauge should show close to 14v. |
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| Author: | ben944 [ Tue Sep 08, 2009 1:11 pm ] |
| Post subject: | Re: Battery problems |
Hi, Most owners replace their batteries every 4 years or so as a matter of course. The 944 motor seems to take a bit of time to crank and get going. Ben  (Missing my '44)
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| Author: | rav [ Tue Sep 08, 2009 5:10 pm ] |
| Post subject: | Re: Battery problems |
Thanks for your help chaps. Brett (Nice car BTW) i measured as you asked. Across battery (car off) - 13.03v (but slowly dropping). Across battery (car on) - 13.85v. Across battery (car on revving to 2k rpm) - 13.85v. Across battery (car on + all electricals on) 13.48v. Across battery (car on revving to 2k rpm and all electricals on - 13.50v. Just the fact that the car is on has increased the voltage - does that mean that the alternator is working? Gauge in the car sill showed only just over 12v.... New battery is £60 so i want to be sure that is what i need before i go and get one. |
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| Author: | tr7v8 [ Tue Sep 08, 2009 5:21 pm ] |
| Post subject: | Re: Battery problems |
rav wrote: Thanks for your help chaps. Brett (Nice car BTW) i measured as you asked. Across battery (car off) - 13.03v (but slowly dropping). Across battery (car on) - 13.85v. Across battery (car on revving to 2k rpm) - 13.85v. Across battery (car on + all electricals on) 13.48v. Across battery (car on revving to 2k rpm and all electricals on - 13.50v. Just the fact that the car is on has increased the voltage - does that mean that the alternator is working? Gauge in the car sill showed only just over 12v.... New battery is £60 so i want to be sure that is what i need before i go and get one. Alternator is OK by the sound of it. Get someone to do a battery discharge test on it. I suspect you have a dying cell. |
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| Author: | rav [ Tue Sep 08, 2009 5:26 pm ] |
| Post subject: | Re: Battery problems |
Thank you - I will do this tomorrow morning. Its always nice to be armed with some information rather than go in blindly. I would hate to buy a battery only for the alternator to have gone.... |
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| Author: | Brett928S2 [ Tue Sep 08, 2009 5:30 pm ] |
| Post subject: | Re: Battery problems |
Hi Ok those tests as Jim says show the alternator is working fine.... Last test to try is a home version of a battery discharge test.... Do this..... ENGINE OFF IGNITION ON ALL ELECTRICS ON (everything you can turn on) Then test battery with everthing electrical on and leave it all on for a minimum of 5 MINUTES..... IF battery is good it will STAY at 11 volts or over..... IF battery is nearly gone it will stay at 10 volts or over.... IF battery voltage drops below 10 volts....take battery to nearest bin ...lol OOPS ...forgot to add, if below 10 volts you will probably need to recharge the battery overnight to get car to start again as there will probably not be enough amperage for the starter motor.... All the best Brett
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| Author: | DavidL [ Tue Sep 08, 2009 7:26 pm ] |
| Post subject: | Re: Battery problems |
Rav, If you need a new battery I have bought 2 silver seal ones from ECP behind Dick Lovetts BMW - they are about £70 and seem to do the job well. I've just had a new alternator and my dash gauge now reads 14 almost all the time! Sounds like the dash gauge is a bit iffy - they often are. If you take the clocks out there will be a flat oval connector held on with a single (7mm?) nut. Take the nut off and withdraw the oval piece - it has 2 long brass coloured prongs. Give these a good wet and dry (even if they look fine) and reassemble.(Disconnect the battery before any of this!) Hopefully that might restore some of your dash reading. David |
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| Author: | rav [ Wed Sep 09, 2009 9:11 am ] |
| Post subject: | Re: Battery problems |
Good old Halfrauds tested the battery this morning. No problems, so ive put it on charge with an old school charger. Not sure what the problems can be now..... |
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| Author: | tr7v8 [ Wed Sep 09, 2009 10:35 am ] |
| Post subject: | Re: Battery problems |
rav wrote: Good old Halfrauds tested the battery this morning. No problems, so ive put it on charge with an old school charger. Not sure what the problems can be now..... Could be lack of use, in which case get either a solar charger or a battery conditioner, good idea anyway. Or you have a discharge (ooerr!) such as the glovebox light or the boot light. |
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| Author: | Nick [ Wed Sep 09, 2009 10:45 am ] |
| Post subject: | Re: Battery problems |
rav wrote: Not sure what the problems can be now..... You may have a faulty starter motor where it can refuse to turn when stopped on a faulty segment or a bad earth connection from engine to body. Nick |
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| Author: | lindsayhbrown [ Wed Sep 09, 2009 7:49 pm ] |
| Post subject: | Re: Battery problems |
my alarm flattens my battery in about 2 weeks, mine lives on its life support (battery conditioner) as the wife calls it |
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| Author: | DavidL [ Wed Sep 09, 2009 8:38 pm ] |
| Post subject: | Re: Battery problems |
My old S would only last a week without flattening the battery whereas the current turbo seems happier for much longer. I always felt I had a drain somewhere but never got round to hunting for it. Can recommend an Accumate battery conditioner - tend to use it on whatever is not in use. |
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