My battery in my car keeps going flat after say 3-4 weeks of the car sitting.

I checked the drain on the battery and it is only 2mA which is not enough to drain a battery in 4 weeks.

I have spoken to 4 other people who have camaro's and they have the same problem. Sounds like something common.

Someone said about the alternator overchraging the battery which shortens the life of it and also means it loses its charge over a short time.

Anyone have similar problem? Any possible fix?

I don't know about the alternator overcharging as I have a digital volt meter gauge hooked up and it shows me around 13.5 volts when I am driving around. That seems to be what it should be like.

Any ideas?

 

i have the same problems with mine. also had the problem with my 87 GTA, 89 iroc, 91 formula. i guess they all go dead after a couple weeks.

 

if you're not driving the car for extended periods of time you're supposed to unhook the ground cable off the battery.

 

BUt this is the only car that ever goes flat on me. I don't even have to drive my other car for 6 months and it fires right up.

The question is why does it go flat?

The problem with u nhooking the ground cable is that you go into learn mode every time you take the car out for a drive.

 

Sounds like a weaker battery rather than a car problem.

 

My 89 will go three months and turn righ over. Whats the voltage on the battery (not in the dash) with the car running. Take the battery out and have it tested, and right.

 

I keep a Battery Tender ($30).... on my 91 Formula...

they do sell battery terminal "switches" to turn (instead of unbolt to disconnect ground, etc... A little faster route..

Rafael

 

I have had 2 batteries swapped over so I doubt both of them are faulty.

The voltage when running is over 13volts.

After 3-4 weeks of standing the battery voltage with key ON is 11.4 volts, and it will not start the car.

I have spoken 4 other owners and they have the same problem. Maybe you gusy drive your car too often to notice it?

 

2mA should be fine for well over a month. I don't start my 89 but once a month at the most, at least for the last year. Maybe the starter motor is pulling to much current? I think the best thing in your case may be a battery tender/trickle charger and leave that on the car and call it good.

 

The best test IS to disconect your ground and see if your battery drains in the same amount of time. Sometimes you can have a battery that 'shows' it is fully charged, but you'll have a bad cell that will show up if you have a 'load test' performed.

Here is a general chart that shows volt readings from a 12v battery:
100% 12.70 volts
90% 12.50
80% 12.42
70% 12.32
60% 12.20
50% 12.06
40% 11.90
30% 11.75
20% 11.58
10% 11.31
0% 10.50

I use a small hand sized european battery voltage maintainer/tender for my RV, as those batteries tend to sit for several weeks at a time. It is tough on a battery to let it run out and then to charge it all the way back up.
Hope the info is a help. Nitro

 

yep mine dies after 2 to 3 weeks of sitting. i think its a normal common thing for F-body.

 

On a side note guys. If you buy an LT1 starter they require a lot less cranking amps. Doesn't solve your draining problem, I know.
But at least you can start your car. They weigh 9 pounds less and they are smaller.

Is there a lot of humidity where you are. Sometimes power drains can be intermittent and often get worse when there is moisture everywhere. It helps if you sneak up to the car to take it's voltage reading also, sometimes they lie if they know your trying to fix them.

Ben

 

I have 2 optima red top batteries. my car sat for over 6 months and fired right up no problem.

 

Another option on battery drain - fuel pump. On my TBI cars, the fuel pump is wired directly to the battery + terminal via the Oil Pressure Sending Unit (OPSU).

I had the OPSU go bad - allowing the fuel pump to constantly run, even when key was out of car. My battery died every 2-3 days, and it drove me crazy until I found it by shear luck - I walked past the car at 3am one night, when all was deadly quiet in the 'hood, and heard the pump running (it's rarely quiet since I'm close to a major roadway). OPSU was the culprit. Open those hatches and lay that ear on the hump (late at night) when battery mysteriously goes dead.

 

Was that the sending unit right above the oil filter?

 

You guys got it easy. My battery dies overnight while its disconected and my battery is only 8 months old, that battery I had before did the same thing. When I go home, I have to put in on the charger.

Is there any type of additive to help with the cells?

 

Yep - that's the one!

 

ya ive heard that to, i only drive mine when it is nice or for club meetings/events. but i start it once a week just to keep it running!!!

good luck

 

1% per day is the normal rate of discharge for a lead acid battery at about 70degF. Factor in ambient temp, if it's cold it drops dramatically and also factoring in NORMAL parasitic drain from the car, usually around 10-15ma/day and you will usually after 30 days only have about 60% of rated capacity. GM does not consider 60% to be adequate for cold cranking. In thier TSB's they consider 30 days the max time for reliable cold start's. Many factors come into play as you see here. The best thing to do is get one of the little cig chargers from Whitney and when the car in not in use give it a constant trickle. it will also increase the life of the battery dramatically.

 

Yep, those little plug in items work great! I have a vehicle that stays stored for weeks at a time between use. I was always having to plug in a battery charger to start it every month (it has a lot of electronic sensors that light up when ignition is off, the stereo system sucks up power to maintain the clock and all the preprogramed stuff, etc) I installed a $20 buck unit thats about 6" x 12", and have never had a problem for the past year.

That was an excellent point about ambient temperature. Battery life drops like a rock as it gets cold(er). Had forgotten about it. Nitro

 

I just went to the J.C. Whitney website. I remember those solar power chargers being around $20. Now there $$$$$!

 

I start the GTA up about once a month and run it for about 15 minutes, so far it's been starting up fine and the battery is about....uh 8 or 9 years old, lol. definately time for a new one but I really only need it to start for me one more time since we're moving to a new place with a 3800sq ft pole building that I can tear it completely apart in.

 

I must have to get one of those trickle charges then. I checked out whitney website and they have a few. 1 for $29 and the other for $15.

 

Silly question: do you have an alarm on your car? My alarm is programmed to automatically arm after 20 seconds. I cannot leave it sitting for more than a couple of weeks before the battery goes dead, unless I deactivate the alarm. Then it will sit for months... if I let it...

 

That's not a silly question at all. It goes along with all the electronics now that are finding their way into our cars. Many of them need power to keep their 'memory' going, or on quick start activation. I think it's a good reason why many people are swaping out their batteries for those Optima deep cycle type Gel batteries, although you have to be really careful when recharging them; Doing a fast 'charge' will ruin them. They need to be recharged on a battery charger's low setting. Nitro