Long story short,
The car was left with the interior lights on for 4 days and the battery was completely dead. Since I needed to take it to work the next day I was in a hurry to get it working again. I used my charger and threw it on the 12V 2 amp charge for about 10 minutes, then switched it over to the 12v 12 amp charge for another 10. At this point it turned over normally and I ran it for about 10 minutes. It seems to be working fine now, but it's summer and I don't expect it should have much trouble starting the car.
So a couple of questions.
1. How badly does this damage the battery?
2. At this point (2 days later), is there any use putting the battery on a trickle charge overnight? I have the 12v 2 amp setting on my big charger, as well as a smaller 1 amp trickle charger I use for my motorcycle and lawn tractor batteries over the winter.
Thoughts?
Car battery completely drained - Too late to save?
- Thread starter D189379
- Start date
- Status
It can be damaging and the battery's reserve has been affected. It's hard to tell how bad the charge has been affected, because doing a practical drain test will only damage the battery more.
I would carry a set of jumper cables in your car if you're worried.
Trickle charger can be helpful to
A) ensure the battery is fully charged.
B) if your trickle charger also says it desfulfates (BatteryMinder for example)this can be helpful to recover your reserve. However, your expectation for the desulfating process should be like in the week's range to recover batteries, not overnight.
Read amazon.com reviews of guys who had like golf-cart batteries that wouldn't hold charge get recovered.
Last edited:
How old it the battery? If it is several years old, chances that it will last after a full recharge are two......Slim and none.
It would be worthwhile to charge the battery until it is completely recharged.
From your description, I doubt the battery was as deeply discharged as you think. It would take a couple of hours to bring a completely, totally discharged battery back to where it would start the car.
An auto supply store should be able to load test your battery for free......After you fully recharge it. A good store could tell you what the current reserve capacity is, giving you a basis for a decision on when to replace.
A trickle charge may allow (or may have allowed) it to desulphate some. There is definitely damage to the battery, though.
I have had this happen to my batteries before and I ran them another year or two in NY Winters without a problem.
This march, someone got into my Cherokee, forced all of the dome light on and killed the battery. Happens, unfortunately. I charged it on and off switching between trickle charger and 2A charge.
Originally Posted By: 4wheeldog
How old it the battery? If it is several years old, chances that it will last after a full recharge are two......Slim and none.
It would be worthwhile to charge the battery until it is completely recharged.
From your description, I doubt the battery was as deeply discharged as you think. It would take a couple of hours to bring a completely, totally discharged battery back to where it would start the car.
An auto supply store should be able to load test your battery for free......After you fully recharge it. A good store could tell you what the current reserve capacity is, giving you a basis for a decision on when to replace.
I would have charged it at the highest amperage available to help dissolve crystals formed from sulfation but who knows how long it will last now. I am surprised it started after such a quick and slow charge. I also would have let it charge full and not have started the vehicle so fast but good luck with it. If it never got below 10.5v you shouldn't have any huge problems.
I would put it on a trickle charger for several days. Bringing a totally dead battery back very slowly is the key. It can't hurt. Yes, the deep discharge probably took some life out of the battery, but even if its a couple of years old you might still get a lot of life out of it with a slow initial recharge. IME what REALLY hurts a battery isn't the deep discharge, its getting a jumpstart and letting the alternator cram 150 amps into it for the first few seconds, over 100 amps for a couple of minutes, then 50-80 amps for the next 10 minutes, then 30 amps for a few hours. Back when cars had 30-amp generators that was less of a problem.
A "smart" charger like this one can also work wonders for bringing an aging battery back to life:
http://www.cloreautomotive.com/sku.php?id=502
my ridgeline's battery went to zero many times in storage etc.
I trickled charged it and then zapped it with a high amp charger.
3 years back I bought a charger with a de-sulfation cycle. it worked better after de-sulfation
just charge it FULLY before running it in the car, a car alternator is not designed to recharge depleted cells.
Like many others have said, I think it depends on the age of the battery.
Without knowing that, I would most agree with 4wheeldog.
Charging at 2A for 10 minutes, then 12A for another 10 minutes only adds up to 2.3 Ah, which is just a tiny fraction of the full capacity of the battery. It would have been interesting to know the voltage of the battery when it was "dead". It likely wasn't completely dead.
I would probably measure the voltage while off, and if it's under about 12.5V (at about 80F), I would hook it up to a charger over night. If there's a desulfation feature, I'd run that.
You drove the car. Assuming it was highway speeds for 30 minutes one way and 30 minutes back, equalling 60 minutes total and your average alternator is 80 amp/hours. You should have recharged at least 50% of it. That's assuming it's got 50% capacity left.
What's I'd do is pop the battery cover and refill with distilled water where necessary. Then take it to work again and back. After driving don't immediately plug the trickle charger. Let it sit a few hours for the battery's surface charge to dissipate. That will allow the trickle charge to more accurately get a true voltage reading. That's assuming your trickle charger is one of those that monitors the voltage and reduces amperage at full charge. Otherwise, if it's dumb, then just plug it.
You'll know your damaging the battery if during charging you can feel too much heat from the sides of the battery. Again, since your engine bay gets hot which heats the battery, that's another good reason to let it sit and cool a bit before charging.
Last edited:
Buy a new battery with AAP discount code.
Just a word of warning. If the battery has truly been discharged beyond adequate recovery, continuing to drive on it is only going to overstress the alternator. A new battery is cheap compared to an alternator.
Once you discharge a flooded acid below about 1.1 specific gravity, sulfation starts and there is usually some capacity damage. You probably don't have heavy sulfation if you caught it quickly, though.
I'd pull the battery from the vehicle and place it on a reconditioning charger with test phase. If it doesn't pass the test phase, I'd immediately exchange it for a new battery. Otherwise, you may be able to squeeze another month or so out of it until the colder weather arrives.
Again, batteries are really cheap compared to charging system components.
Sorry, I should have added that the battery is 2 years old. I have no idea how discharged it was, just that the door locks didn't work, no lights on the dash came on when I tried to start it, nothing at all.
I'm mostly worried that I won't notice the effects until the middle of winter during a cold snap.
Don't "fix" something until you know for a fact it is actually "broke".
If its starting up OK, simply run it until you see problems. All batteries will die at some point, and yours may or MAY NOT die early. Just carry cables like you should anyway, and get all the life you can out of your battery. FWIW, I don't think interior lights totally killed it.
You may be just fine, since the battery was probably not really fully discharged and you didn't leave it sitting for weeks or months.
I've done something like this and the battery was fine thereafter.
Volvohead has a good point in that if the alternator is worked hard in trying to restore this battery, it may get fried and an alternator costs more and is harder to replace than a battery.
Putting a charger on it would not be a bad idea, since the alternator will not bring the battery to full charge unless the car is driven at steady highish revs for quite a number of miles, like a couple of hundred mile highway trip.
You probably lost ~ 5-10% of the capacity. I would charge it at a slow rate of <5 ampers for 10 hours or until the charge tapers to less that 1 amper.
I do it repeatedly. Actually It is a result of marrying and mixing genes with my wife. The off portion of a switch doesn't enter into her consciousness.Lights are on every where. Covers are set on, not screwed on. Doors open only. At least one of our offspring has inherited the gene. Couple that with a car that draws 20 mA and sits for weeks at a time. The 3 yr old Value Craft get drained I have a 2/10/ 75 charger, a 5$, 1/2 amp floater from Harbor Freight.The floater works well,only if the battery is charged. I have used it once or twice. The Rat starts instantly, The charging system has a new belt. and the little VC gets enough juice to start it. I also have a jump box that will start a flat battery. Also heavy gauge jumper cables. In both cars. On a daily driver, a good battery will keep the alternator from over use. The 14.1 V regulated output of the 528es alternator makes for a long life. However it doesnt recover a battery very well. The charger set on 2 amps overnight. If you play the radio for 3-4 hrs with the engine off, can you start the engine? That is the sign of a good battery. If the play time is less than 2 hrs, start shopping for a new battery. The Rat is set for 14.5V and will pump up a flat batt pretty fast.
Why sweat it?
Just use the Advance Auto Parts 40% off coupon and buy a brand new fresh battery, that way no worries in the dead of winter.
- Status
