How long to charge Dead Car Battery

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  • #1
russ_watters
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Just got a jump start due to having left my trunk ajar last night. Battery was pretty dead ~8.5V. Dead enough that we had to let the jumper car charge it for 10 minutes before it would start. So now it is running in my driveway. How long do you think it will need to charge before it will be safe/charged enough to turn off?
 

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  • #2
Doug Huffman
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As many hours as you can afford. I am informed that the on-board charging will not restore a dead battery to full charge in reasonable time, demonstrated by a ~5 watt load killing the battery. What is the temperature? Here it's about 10F.

All of my vehicles are diesel. Their batteries are fully charged and watered before the temperatures start to drop.
 
  • #3
nsaspook
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If you want the battery to last it needs a full charge cycle to move the sulfate complete away from the plates to recover full capacity. Running your car for hours is not the best way to do it. Buy or borrow a good multi-stage battery charger of at least 15A but not too much current or it will warp the plates and let it run full cycle. I have this, it works great: https://www.amazon.com/dp/B000H961YI/?tag=pfamazon01-20
 
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  • #4
phinds
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Just got a jump start due to having left my trunk ajar last night. Battery was pretty dead ~8.5V. Dead enough that we had to let the jumper car charge it for 10 minutes before it would start. So now it is running in my driveway. How long do you think it will need to charge before it will be safe/charged enough to turn off?
Uh ... do you mean the car would not start WHILE the jumper car was providing juice? I've never heard of a battery that dead. If that's the case, I think you may have other problem, although it does sound like you identified the culprit in the battery discharge.

Answer to your question depends on how cold it is out. If not too cold, 1/2 hour should be plenty. If frigidly freezing out, I don't know.
 
  • #5
russ_watters
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It's 30F. I'm going to stop it at half an hour. I'll look into a charger. Tonight I'm going on an hour drive, which should get it as charged as it is going to get on its own. And I'll make sure my jumper battery is charged this time...

[edit] 13.0V after I shut it off. So I think it should be ok for now...
 
  • #6
Borg
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It's 30F. I'm going to stop it at half an hour. I'll look into a charger. Tonight I'm going on an hour drive, which should get it as charged as it is going to get on its own. And I'll make sure my jumper battery is charged this time...

[edit] 13.0V after I shut it off. So I think it should be ok for now...
I was going to suggest driving around for a half hour or so. That usually does it for me.
 
  • #7
Doug Huffman
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XRP Series 7-Stage Battery Charger — 12 Volt, Model# 60109
Serves me well.
 
  • #8
nsaspook
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XRP Series 7-Stage Battery Charger — 12 Volt, Model# 60109
Serves me well.

Nice charger.
It's very important in cold weather for the battery to get a complete cycle charge to completely reconvert the plate sulfates back to plate oxides. At 8.5 volts some capacity might be lost permanently but most can be recovered with a good charger.

Car charging systems are designed to maintain a good battery not recharge a dead one.
 
  • #9
dlgoff
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I'll look into a charger.
This thread could go in the EE forum and since this is a Science Forum ... I have to post this:

clead1.jpg


Image compliments of Battery University.
 
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  • #10
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If you want the battery to last it needs a full charge cycle to move the sulfate complete away from the plates to recover full capacity. Running your car for hours is not the best way to do it.

Most every thing you need to know about a lead-acid battery ... charging and discharging, sulfation, and freezing, just about every battery failure mode is metioned...

If you do not like Wikipedia[1], then look here...



Always remember[1] ...
Wiki isn't a credible source, since wiki pages can be edited by anyone.

Even by me ...lol
 
  • #11
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Heat really gets to car batteries here in AZ.

It will be interesting to see batteries start to evolve, so to speak, when more and more new cars automatically shut off the engine when the vehicle comes to a stop. Then the engine restarts "instantly" when the driver presses the gas pedal.

The auto industry will also have to improve starter motors to a great degree I presume. There are glass mat batteries and gel batteries now but they cost a lot more, especially gel batteries.

I wonder if we will ever get away from lead acid batteries? Buying lithium ion batteries of that size would require a bank loan.
 
  • #12
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I have an old battery charger I bought a few years ago at the swap meet for $10. It has served me well the times I've left something on overnight.
 
  • #13
russ_watters
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It got me to Harrisburg, so I'm good for now...
 
  • #14
nsaspook
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Most every thing you need to know about a lead-acid battery ... charging and discharging, sulfation, and freezing, just about every battery failure mode is mentioned..l

All good sources of information. As a hobby I design solar energy battery status monitor systems.
That hunk of lead and acid is a lot more complicated than most people think.
 
  • #15
RonL
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It will be interesting to see batteries start to evolve,
I wonder if we will ever get away from lead acid batteries? Buying lithium ion batteries of that size would require a bank loan.

Why get away from something so cheap to make? Just make it so that it doesn't fail. (this would be kinda like thinking inside the box:) )
It can be done, just saying...:D
 
  • #16
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Why get away from something so cheap to make? Just make it so that it doesn't fail. (this would be kinda like thinking inside the box:) )
It can be done, just saying...:D

They have to fail or the companies couldn't sell new ones. :D
 
  • #17
nsaspook
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I wonder if we will ever get away from lead acid batteries? Buying lithium ion batteries of that size would require a bank loan.

For just starting an ICE engine once every few hours lead acid batteries are hard to beat. They can designed to be extremely robust and tolerant of charging abuse when used as traction batteries in things like fork-lifts where they are run flat everyday and recharged at very high charge rates.
 
  • #18
256bits
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Dead battery --> half hour on the charger --> car starts. Cold weather needs more time. Bring the battery indoors to warm it up.
( oh. Phinds already said that )
Been there. Done that.
You won't notice it now, but a discharged car battery takes something like 6 months, or so, off its useful life, but since you don't know how long it was going to last anyways you will never reflect back on the time it was discharged.
Sulfication is never fully recovered. Each start of the car discharges the battery a bit. They finally have to be replaced.
 
  • #19
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For just starting an ICE engine once every few hours lead acid batteries are hard to beat. They can designed to be extremely robust and tolerant of charging abuse when used as traction batteries in things like fork-lifts where they are run flat everyday and recharged at very high charge rates.

No doubt about that. But they do have to be maintained. Car batteries used to have cell caps that screwed in and out. It was no problem to add water, or check specific gravity. Now some batteries (maintenance free) don't even have a way to check anything. Others have to have the tops pried off.

We lose water rapidly here in the heat yet even with an oil change most shops don't touch the battery. I have never had a battery make the full warranty period in AZ.
 
  • #20
dlgoff
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Car batteries used to have cell caps that screwed in and out.
My first car was a '51 Chevy (~16 yo). Remember the 6 volt batteries? One cold snowy winter night some friend and I were parked out in the country drinking beer in large quantities. When we were ready to leave, the battery wouldn't turn the engine fast enough to start and stopped trying in about 3 seconds. Well ... went out, popped the hood, unscrewed the 3 caps, observed no water, and being drunk and needing to relieve myself, ... Amazing how fast the engine turned over with new hot electrolyte.
 
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  • #21
nsaspook
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My first car was a '51 Chevy (~16 yo). Remember the 6 volt batteries? One cold snowy winter night some friend and I were parked out in the country drinking beer in large quantities. When we were ready to leave, the battery wouldn't turn the engine fast enough to start and stopped trying in about 3 seconds. Well ... went out, popped the hood, unscrewed the 3 caps, observed no water, and being drunk and needing to relieve myself, ... Amazing how fast the engine turned over with new hot electrolyte.

I wonder that the storage capacity is for a lead uric acid battery?
http://www.halfbakery.com/idea/Uric_20acid_20oxidation_20battery
 
  • #23
nsaspook
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Lol. I should get some credit for it's discovery. :mad:
Too late, a better battery is made with #2.
 
  • #24
dlgoff
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Too late, a better battery is made with #2.

:oldlaugh::oldlaugh::oldlaugh:

So are those the ones you are designing this around?

As a hobby I design solar energy battery status monitor systems.
:devil:
 
  • #26
dlgoff
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Some of the batteries I renew are full of crap when I get them but with a good flush and some new electrolyte most are good after a few charge/discharge cycles.
https://www.flickr.com/photos/nsaspook/sets/72157622934371746/
WOW. You should make a thread in the EE forum of some of these photos with a "write up". I love your work spook. :oldlove: And I'm sure others would too.

Happy 2015
 
  • #27
Doug Huffman
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Heat really gets to car batteries here in AZ.
Gassing voltage is an decreasing function of temperature, about 2.4 cell volts at STP. Adjustment of charge voltage for TVG is beyond the capability of automotive voltage regulators. On a hot day and with hot under hood temperatures, the water is gassed away, likely never to be replaced.
It will be interesting to see batteries start to evolve, so to speak, when more and more new cars automatically shut off the engine when the vehicle comes to a stop. Then the engine restarts "instantly" when the driver presses the gas pedal. The auto industry will also have to improve starter motors to a great degree I presume.
Not idling an IC motor is key to efficient fuel use. My '03 diesel has its original starter and components and second battery and is manually shut off at about two minutes idling time (time to cool the turbo charger, also original).
There are glass mat batteries and gel batteries now but they cost a lot more, especially gel batteries. I wonder if we will ever get away from lead acid batteries? Buying lithium ion batteries of that size would require a bank loan.
Lead acid batteries have been commoditized and all but forgotten. With minimal adequate maintenance they should last five years and hundreds of full charge/discharge cycles. It is quite likely that some original components of the original Gould TLX-39B are still in use. I believe that only the lead alloy has changed over its lifetime.

My Island power company still maintains redundant DE generators capable of supplying 2.5MWe and 100,000 gallons fuel. Only within the last year or so was the original 60 y.o. field flashing battery replaced.
 
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  • #28
nsaspook
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WOW. You should make a thread in the EE forum of some of these photos with a "write up". I love your work spook. :oldlove: And I'm sure others would too.

Happy 2015

One day. I'm slowly working on a off-grid redesign for my retirement home that's a little better organized than something made from scrap parts from work.
 
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  • #29
Pythagorean
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I've never done controlled experiments, but in similar situations for my Mazda b2600 (a 4wd four banger) I would let it run 15 min every time I used the starter and that always gave me enough charge for the next start.
 
  • #30
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If a battery won't come up to full charge as indicated by my old analog charger I check the specific gravity the old fashioned way. I always find at least one cell with a very low SG and one next to it will be low. I take them back if they are still under warrantee and in AZ they usually are.

The last one I returned was to Sears. They always did load test batteries before they replaced them but this time they had a new machine. The guy at Sears told me that he had to put the battery on their new computerized load tester and that it would take an hour. I told him I would wait.

I stayed close enough to see the lights on the machine do their thing. Less than 15 minutes had passed and I noticed a red flashing "Replace Battery" light. I had to go find the guy. For some reason he really thought that it would take an hour.
 

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