How Much Driving Will Recharge Drained Battery?

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batteries

#1

Doy!!! I left my lights on for 4 days and completely drained my '98 Volvo S70 battery. After a nice church van stopped to give me a jump, I drove about 40 minutes and stopped the car. I needed a jump to get it started! I thought batteries charged quicker?


#2

Head lights on for four days

I suspect that the battery is gone. That would kill most batteries and damage most of the rest.

Don’t try to drive it any more, as you may be damaging your charging system trying to charge the dead battery.

Time for a new battery, or at least buy a plug in battery charger and follow the instructions on the charger, but I doubt if it will do any good.


#3

If your battery were still good it would take but a few minutes to charge enough for an immediate restart, and maybe 20 minutes or less for a full recharge. It appears your current battery is now worthless. Replace.


#4

wow. I didn’t know you could kill a battery by draining it. Darn! So, is that something I could do myself on the street if I buy a new battery?


#5

Yes, just be sure to disconnect the NEGATATIVE terminal of the battery first. If you have the wrench on the positive terminal and touch any metal part of your car, you might weld the wrench to that part. At the least, it could be very exciting!


#6

Yup, I trashed a fairly new battery a few weeks ago. I was traveling and my alternator failed, by the time I had the alternator replaced I had drained and recharged the battery several times. It seemed OK for a couple of days with the new alternator, then it completely died.


#7

A battery in good condition will survive a few total discharges. Your battery was likely on its last legs before the incident.

Yes, replacing a battery is a simple procedure by the owner. Bring the old one with you when you are ready to buy. You typically get some sort of core charge discount and they will also take care of the disposal problem for you.


#8

Well, it could be a fried battery. or it could be that the nice church van disconnected the jumper cables too soon, so there wasn’t enough charge in the battery to supply the field coil of the alternator, so the alternator output was too low to charge the battery and supply the cars requirement too.

If it is the battery, better get a new one soon. A bad battery draws excess current and that can burn up the alternator.


#9

Make sure that all your warning bells and things are working. Some people hear them and just walk away without checking.


#10

That’s nowhere near long enough to recharge a stone dead battery. Yes, it is detrimental to completely discharge your battery. In fact, it’s not good to go even below 75% of full charge for any length of time. However, unless your battery was on its last legs, it may be recharged and give you many years of good service. You need to trickle charge the battery to replace the energy lost. It will likely charge at 8-10 amps for at least 24 hours.

40 minutes is 0.66 hours. A typical alternator may put out 100 amps for example. Much of that can be consumed by the vehicle, especially if you run fans as an example while the battery is trying to recharge. So you’re not getting the full charge capability of the alternator while driving. Let’s say your getting 60 amps to the battery. 60 amps * 0.66 hour is only 40 amps!! Not nearly enough to work the starter motor which can draw hundreds of amps for short periods needed to crank the engine.


#11

Oops, that should read “only 40 AmpHours”!


#12

Huh?! A battery with 40 amp-hrs of charge will easily start a car that is otherwise ready and willing to go. Less! Anyone with even a decrepit 10-amp battery charger will tell you it doesn’t take all day just to get that one crucial start.

I’ve taken a stone-dead battery up to starting power in about 30 minutes. We all have. What’s that? – 5 amp-hrs? You can insist it’s not supposed to work, it can’t possibly work. OK, you can wait your 24 hours; that won’t bother me a bit.


#13

Follow-up…

I had the battery tested last night and it was “good” but not charged. They offered to charge it, but since I have 12 hours to drive this weekend, I didn’t want to take any chances. So I bought a new battery for $90 and had them install it ($7.99). Plus I got these really nice wiper blades.

Maybe I should have had them charge it up instead?


#14

Maybe I should have had them charge it up instead?

Naw, if you don’t trust the battery and your going on a trip, just replace it. Batteries are cheap and getting stuck away from home is a hassle.


#15

I never said it would take all day to get it to start. That’s your interpretation of my post. It will take all day to get it FULLY charged, which is what should be done to a discharged battery. Not give it a minimal charge and take off fat, dumb and happy.


#16

I think you made a wise decision. If the “good” battery decided to give it up during the trip, that could take out your alternator as well. Alternators ain’t cheap.

I usually buy the cheapest battery that I can find. I don’t know why, but I’ve had much better luck with the cheap ones than the expensive ones.


#17

I’ve done the same thing. My battery was fairly new though and I stuck a brand new battery charger on it and it came back to life quite nicely. This was after trying to charge it with the automobiles charging system which couldn’t quite get the job done. Admittedly I have an old volkswagen with a generator/ voltage regulator setup, so the crummy 30 plus amp generator might have been part of my problem.


#18

Actually, it is better to recharge slowly, especially when the battery is really drained. Dumping too much current into the battery too fast can warp the plates and lead to other problems.