New Battery, or recharge?
Thread Starter
Race Director
Joined: Oct 2011
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From: Dallas Texas
2025 C4 of the Year Finalist - Modified
New Battery, or recharge?
I left my interior lights on all of last night, till this morning. Multimeter reads the battery voltage a 7.2
Is it OK to recharge it, or do I need to buy a new one?
Is it OK to recharge it, or do I need to buy a new one?
Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi
Melting Slicks
Joined: Jul 2005
Posts: 2,649
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Absolutely no harm in trying to recharge it. Just avoid the higher amperage settings on the big chargers - the only way to get a battery to accept 20 - 50 Amps is to push the voltage WAY up, and that's not the best thing for the battery.
After recharging - it certainly wouldn't be a bad idea to do a load test on it - many places will do that for free.
After recharging - it certainly wouldn't be a bad idea to do a load test on it - many places will do that for free.
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Le Mans Master
Joined: Jan 2006
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From: Orlando FL
You're in a hot place as I am and 2 or 3 years on a battery time is running out. I'm sure you can charge it and all will probably be OK. If you run the car several times a week it will stayed charged and will never see the difference in getting it started.
But the real difference is the reserve power. If you ever lost the alternator of broke the belt you would be running strictly on the battery. If there's not much reserve left, you'll be sitting on the side of the road and not make it to your destination.
The heat really take a toll on the battery and depending on the age you will have to decide which way to go at this time.
But the real difference is the reserve power. If you ever lost the alternator of broke the belt you would be running strictly on the battery. If there's not much reserve left, you'll be sitting on the side of the road and not make it to your destination.
The heat really take a toll on the battery and depending on the age you will have to decide which way to go at this time.
Thread Starter
Race Director
Joined: Oct 2011
Posts: 16,092
Likes: 819
From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Got it charged. It doesn't go below 14 volts at idle, in gear with a warm engine. Before I left the lights on the other night, it would go to like 13.2 volts with all accessories. Now just 14. Is that bad?
Last edited by 1993C4LT1; Aug 26, 2016 at 10:00 PM.
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Burning Brakes
Joined: Oct 2001
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From: TN
Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi
No, this is really an indication of your alternator not the battery. The battery appears to be fine and your alternator is fine.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
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From: Mystic CT
OK not to hijack but I have a battery that runs down in around 3 weeks hooked up. Charged at 15 amps for 4 hours and claimed charged and then 2 or so amps for 6 and never reached charged and hooked up to nothing. Will try a 2 to 6 amp charger tomorrow for a few hours. off the charger 12.91 volts 24 hour later 12.61. Checked standby load at under 30 ma. Is it the charger or is the battery a bottomless pit or junk?
Instructor
Joined: Jul 2016
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From: Plymouth MI
OK not to hijack but I have a battery that runs down in around 3 weeks hooked up. Charged at 15 amps for 4 hours and claimed charged and then 2 or so amps for 6 and never reached charged and hooked up to nothing. Will try a 2 to 6 amp charger tomorrow for a few hours. off the charger 12.91 volts 24 hour later 12.61. Checked standby load at under 30 ma. Is it the charger or is the battery a bottomless pit or junk?
Still, three weeks is a long time to sit. I'd check how much the car is drawing and go from there.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Doing some research the average car battery has a 40 amp/hr. standby to power something and still be useable to start a car. 30 ma is 21.6 in a month so should easily start up. The other is the battery never seems to get to the point the charger says it is charged. Will try a different charger tomorrow.