Hot Rods My car keeps killing batteries, why?

the reason why do not ad the plug in is people are lazy or dumb and wouldn't do it . its too much for them to have oil changed on leases , disposable cars ..

 

Truck 64 is on the money Chris. I've had the same happen to me. Find the drain and then go optima


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I put the pos battery on a charger and it never would get to 12 volts. To 11.6 and if I put the tester on it i could watch it discharge by 100th per second. Bad battery. But odd it's my 2nd one. I'll go everyday battery tender for now. New battery charging at 13 or so so I don't think it's over charging. But some great ideas and things to check on thanks guys

 

"DeSulfation" is kind of a misnomer, all chargers desulfate because that's how it works. The old school method of checking the electrolyte specific gravity is because the electrolyte turns to water as the battery discharges, and the sulfer is bound to the plates, the gravity test measures this. That's probably a simplification but close enough. That's why water only is used to replenish a low battery and not battery acid, the acid is already bound up in the plates, and does not evaporate, and will return to the electrolyte during charging.

The sulfation turns hard fairly quickly though. Maybe it can be "rejuvenated" with a fancy charger, or even a not so fancy charger. Better to keep it on a tender or trickle charge now and then. But the old school "dumb" chargers will charge in ways that the maintenance chargers can't. While it's possible to overcharge a battery it does take effort.

Getting way off into the weeds here, but charging is misunderstood. To get maximum life and performance, a battery "likes" to cook for a while on a charger, and a slight overvoltage is also beneficial, as it evens out the charge between cells.

It takes about 2 volts above the resting voltage at 70°F for a battery to even approach a full charge. That's why 14.5 volts or so is usually seen with alternators. Different car makers have a different idea on what the setpoint is. But a battery will be moderately gassing before it's close to a full charge. This is a good thing. I usually let them cook for several hours at 14 to 15 volts when charging. Slow, low amp charging is best.

If you ever get insomnia or a geek like me, this is hands down the best Battery website for info on charging and charts and tables and the rest of it.

http://www.batteryfaq.org

 

Northern Tool sells a solar battery maintainer. Great for seldom used cars . You can hard wire it in and put it on the rear package shelf or alligator clip it to the terminals.
We were constantly replacing batteries in seldom used police training vehicles until discovered them.

 

I'm a big fan of the optima battery myself. I had one go 10 years and I wasn't exactly kind to it I let it discharge several times and it kept coming back. A cheaper alternative is an AGM absorbed glass Mat of a known name brand which is what the optima is but cheaper. I read the whole thread and didn't notice what brand battery you were using. I've seen Walmart batteries go bad real quick.


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It does sound like a bum battery. How often is the car used? I have a fresh Exide battery (buddy is a dealer for them) in my Ford, size 24. Before I got my tender, the car had sat for a couple of months in the fall following my heart attack, but it started right up. It charged a little high until the battery was topped off. I was working on it most of the winter and had the tender on it, always kept the battery fully charged.

 

My guess is you have just one of the 6 diodes out in the alternator. When one goes out it is hard to detect but does strange things to the battery. Looks like it is charging but isn't. I know it sounds strange but it's true. d2_willys experience described above is evidence.

 

Can perform your own battery diagnostics without hauling it in. Measuring the open circuit voltage is useful. Batteries have a "surface charge" that must be removed for an accurate measurement. Letting the battery set for a day or two, it will settle down. Or, turn the headlights on HI beam for five minutes. Then wait at least ten minutes. The voltage will bounce back over that time to an accurate figure. 12.65 volts at 80°F is 100% charge for a standard lead-acid automotive start battery. Maintenance free batteries are made differently, and a 100% charge is 12.80 volts. Tenths of a volt matter a lot, because the difference between 100% charge and dead is less than a single volt.

A battery with a dead cell will usually characteristically indicate around 10.5 volts. It's done. Can perform a kind of load test by disabling the ignition and measuring the battery voltage at the posts while cranking the starter for 10 seconds or so. The battery should be fully charged for this test. The voltage should not drop below 9.5 volts during this test. A healthy battery will do a lot better, and maybe drop no lower than around 11 volts. Be sure to charge it back up after the test.

A big mistake a lot of people make is thinking that the generator or alternator can recharge a dead or discharged battery. They are not designed for this and the stator or diodes can be damaged. A jump start will get you going, but the battery should be recharged thoroughly as soon as practicable.
The battery and charging system work as a team, but a defective battery can hork the alternator, and a defective alternator can hork a battery. Can get kinda spendy after a while, in the "battery of the month club"!

 

I had that same thing happen to my '64 Corvette. Leaky diode! Battery kept going dead, alternator was warm.


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