Automotive How long to charge Dead Car Battery

AI Thread Summary
A dead car battery, measured at about 8.5V, may require a significant charging period to restore functionality, especially in cold weather conditions like 10F. While running the car can provide some charge, it is not the most effective method; a good multi-stage battery charger is recommended for a complete charge cycle to recover battery capacity. Cold temperatures can hinder charging efficiency, and it's suggested to drive the car for at least a half hour or use a dedicated charger for better results. Regular maintenance and proper charging practices are crucial to prolonging battery life and preventing sulfation. Ultimately, lead-acid batteries remain a reliable choice for starting internal combustion engines, though advancements in battery technology are anticipated.
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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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.
 
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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russ_watters said:
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.
 
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...
 
russ_watters said:
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.
 
XRP Series 7-Stage Battery Charger — 12 Volt, Model# 60109
Serves me well.
 
Doug Huffman said:
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.
 
russ_watters said:
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
nsaspook said:
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] ...
lisab said:
Wiki isn't a credible source, since wiki pages can be edited by anyone.

Even by me ...lol
 
  • #11
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
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.
 
  • #14
OCR said:
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
edward said:
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
RonL said:
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
edward said:
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
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
nsaspook said:
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
edward said:
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
dlgoff said:
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
dlgoff said:
Lol. I should get some credit for it's discovery. :mad:
Too late, a better battery is made with #2.
 
  • #24
nsaspook said:
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:
 
  • #25
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  • #26
nsaspook said:
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
edward said:
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
dlgoff said:
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
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
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.
 
  • #31
RonL said:
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
Super Capacitors! if I understand right is just "static" electricity. but how to stop "leakage"? None the less The power requirement of starting a Gasoline engine pairs well with a cap. Environmentally, lead acid batteries are bad for a number of reasons, in comparison to a Capacitor. Though are "highly" recyclable.
 
  • #32
nitsuj said:
Super Capacitors! if I understand right is just "static" electricity. but how to stop "leakage"? None the less The power requirement of starting a Gasoline engine pairs well with a cap. Environmentally, lead acid batteries are bad for a number of reasons, in comparison to a Capacitor. Though are "highly" recyclable.

The equivalent capacitance of a small car battery is huge. (15,000 F)

A SC with normal car starter motor cranking capability would be at least several times the size of a same capacity lead-acid battery. I'm sure you could make 1 or 2 second cranking system with Super Capacitors in about the same space as a car battery but unless it's combined with a battery of some kind to maintain voltage it's not very practical for daily use (operating car electronics with the motor off) and would be more expensive than a just a good battery.
 
  • #33
Read this thread yesterday and by god my battery went dead while sitting at the bank. The bank teller asked me what was wrong and sent the security to charge my battery. They were all nice. I also have a bunch of money in their bank, so they better be. I knew my battery was weak, because when I had an oil change about a year ago they told me my battery was weak and should get it replaced soon. I apparently wanted to wait until I got stranded somewhere.
 
  • #34
leroyjenkens said:
... by god my battery went dead...
OCR said:
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...

ROFLMAO... I'll have to edit Wikipedia now, just to add that... :oldgrumpy:
 
  • #35
So, the battery has been working "ok" for the past few weeks, but starting is a touch slow and the voltage is down from where it should be. After running it for a while and then letting it sit for a couple of hours, it reads 11.9 volts and leaving it overnight, it decays to 11.3. According to a chart on wiki, that represents a half charge and near completely dead.

So do you guys think re-conditioning will help?

I'm going to buy a charger, but I don't really want to spend $120 if I don't have to. Looking at Amazon, that apears to be about par for the course though. Opinions?

Also:
Starting batteries are lighter weight than deep cycle batteries of the same battery dimensions, because the cell plates do not extend all the way to the bottom of the battery case. This allows loose disintegrated lead to fall off the plates and collect under the cells, to prolong the service life of the battery. If this loose debris rises high enough it can touch the plates and lead to failure of a cell, resulting in loss of battery voltage and capacity.
I'm guessing this is what causes sudden failure of a seemingly ok battery? Like what leroy experienced? I had the same thing a few years ago: First time I noticed an issue, I was at work and the car took a few extra tenths of a second to fire up when I left for lunch. By the end of the day, it was completely dead.
 
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  • #36
How long do you expect to keep the car? If no more than a few years, I would just opt for a cheap battery with a 24 month warrenty.

BTW, congrats on the round number Russ. 23,000! :w
 
  • #37
Borg said:
How long do you expect to keep the car? If no more than a few years, I would just opt for a cheap battery with a 24 month warrenty.
No less than 3 more years, probably more like 5 (it is less than 3 years old now: 50,000 miles). So if I replace it, it will be with a good battery.
BTW, congrats on the round number Russ. 23,000! :w
Thanks!
 
  • #38
russ_watters said:
it overnight, it decays to 11.3.
That has the ugly sound of one cell having an "adolescent identity crisis." I've never been able to straighten them out when they "rebel" and reverse polarity.
 
  • #39
My automotive electrican sez that you'll over work the alternator, you really should charge the battery.
 
  • #40
russ_watters said:
It got me to Harrisburg, so I'm good for now...

As they age they lose capacity. It's a gradual tapering .
I learned to tell by the sound of the starter when a battery was nearing end of life. It's more pronounced in a diesel with its twenty-something to one compression... if it drops below 9 volts while cranking it's weak.
Five years isn't too bad for a OEM battery.
Dont buy a cheap one is my advice. I've had two from "bargain" auto parts stores fail when inter-cell connectors inside cracked. One of them i tried to check cranking voltage and it exploded in my face, blew the top off and spattered acid everywhere. Good thing i was wearing glasses.. acid wrecked a pair of Dockers and a good shirt.
The neighbors came running over thinking somebody had got shot.
Moral: only check cranking voltage from cigarette lighter socket with hood closed.

About fifteen years ago Consumer Reports did one of their studies and concluded that over 3/4 of the batteries in US are made by Johnson Controls. They're sold under myriad brand names.
At the time that's where Wal-Mart got their batteries. CR recommended Walmart because they sell so many they're always fresh.

my two cents

old jim
 
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  • #41
ps i use the generic 6 amp charger. I prefer the heavy ones with a ferroresonant transformer, but they're getting hard to find.
My neighbors have not had good luck with the all electronic computerized-inverter ones.
http://www.tractorsupply.com/en/store/travellerreg;-2-6a-manual-battery-charger-101588799--1

http://media.tractorsupply.com/s7viewers/dhtml/images/spacer.gif
1015887?$prod_det$.jpg

http://media.tractorsupply.com/s7viewers/dhtml/images/spacer.gif
Get one at a yard sale and replace the wires. Sniff it for burnt transformer smell, though.

old jim
 
  • #42
jim hardy said:
...
Five years isn't too bad for a OEM battery...

my two cents

old jim

That reminds me. My brand new truck is now 6 years old, and hasn't been starting as fast as she used to. hmmmm...

12.46 VDC

Time for a new battery.

Although a value of 12.46 indicates my battery is at around 80% charge, it should be reading 100%, which is around 12.6 volts.
I destroyed my last deep cycle battery this winter, by ignoring it. I just checked it, and it's reading about 12.3 volts, which indicates that it's 50% charged.
But, my last test discharge, even after being fully charged, indicated it had pretty much zero capacity left.

@russ_watters , you never did tell us what kind of new battery you got. As I mentioned, I'm now in the market for a new one.

ps. This thread reminds me of my very first "helpy" post.
Danger seemed to approve.
Probably a bad sign.
 

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