Fully charged battery

[tiwebber]

I read here that a fully charged battery is about 12.6 volts. 1/2 discharged at 12.2.

I left the lights on in my car on vacation. The batteries were dead! 3.x volts dead. I put them each on a slow charge for 16 hours or so. The first one got up to about 12.3 volts after I let it sit for a few minutes. After 4 hours it was down to 12.0 volts. I just measured it again and now its a wee bit below 12 but close. I assume the second one will be in much the same shape.

My batter is an Interstate. Should it be 12.6 fully charged if it was functioning as new? Is 12.0 OK/safe to try? I'd like to stick em back in the car and give them a shot but I dont want to risk damage to my Alternator or Regulator (amongst other things that I have ready can get fried if the battery is bad). But if 12.0 is OK and if there's a chance the number will improve (i also ready that over time trickle charging might reduce sulfation if that is indeed an issue here) I might like to give them a chance. Any thoughts?

[DRACO A5OG]

Take it to a local parts store and have them test it.

[tiwebber]

Yeah, I am going to do that tomorrow if using these batteries might be unsafe. We have a local Interstate dealer. I just thought maybe a voltage test and watching the decay of voltage over time might shed some light. The Interstate dealer said that is exaxctly what he'd do in addition to Hydrometer and resistance test. I have a Hydrometer too. My manual says the specific gravity of the fluid in the OEM battery was 1.285 fully charged. 1.230 half charged and 1.142 fully discharged.

[RWebb]

I think I read somewhere that a typical charger will not fully charge the battery, FWIW

[John W.]

Completely discharging a battery is hard on them and it'll take awhile for it to recover. After 16 hours, you got 12.3V. I'd put it in the car and drive it around. Hopefully in a few weeks it'll recover.

[proffighter]

[QUOTE=tiwebber;6185059]...that a fully charged battery is about 12.6 volts. 1/2 discharged at 12.2. QUOTE]

No. Theoretically each cell has a max of 2.4Volts. So car batteries with 6 cells are 14.4 Volts. But you never reach. As soon you remove charger, it already drops. A fresh one stays at about 13.8V. All under 13V is not in good condition. If it drops to 12 or deeper soon, it has to be replaced. Depending on capacity, it's not able anymore to crank an engine strong enough and leave any power for the ignition

[Vereeken]

You should try it.

The charge that remains is enough to start your car.

If after a week of driving you still see the voltage dropping away after the car has been shut down for a while then they are toast.

If you would have drained your battery like this when freezing outside they could have short circuited but at summer temperatures I doubt it.

But clearly you have not done them a favour )

The future is in electric cars (yeah right).

Michel

[rick-l]

Originally Posted by tiwebber

I put them each on a slow charge for 16 hours or so. The first one got up to about 12.3 volts after I let it sit for a few minutes. ?

What is a slow charge? If the battery has 90 Amp hour capacity to charge it in 16 hours you need >5 amps.

Are these batteries hooked in parallel or is this from two cars?

You won't hurt your alternator charging a battery. That is what it is made for.

[Vereeken]

He has a 72. So i guess he has the option of 2 batteries fitted.

They improve handling )

A dead battery can cause your alternator damage when it is short circuited or overheated.

[rick-l]

OK
If you find one is bad don't hook them up in parallel.

[tiwebber]

Originally Posted by rick-l

What is a slow charge? If the battery has 90 Amp hour capacity to charge it in 16 hours you need >5 amps.

The charger has a 6 Amp and 2 Amp setting. I used 2 Amp because I read that a slow charge would be better to reduce any sulfation. I left the charger on the first battery that had 12.3 volts (after a few minutes of without charger). It now has about 12.7 volts (after a few minutes) without charge. That's improvement!

[HawgRyder]

Think of it this way...if you have any doubts about the battery/batteries replace them!!
You only have to get stuck on the side of the road out in East Broken Piston Idaho (out of cell range) at 2:00AM just once to realize how dark the night can get.
That one passing car every 4 hours will not stop to help you.
But...you saved what?....maybe $200?...good for you.
The tow truck won't cost you any more than maybe $500!
Replace the battery.
Drive the car with confidence....after all...there are only 200 - 300 more things that can go wrong...LOL.
Have fun.
Bob

[tiwebber]

Originally Posted by HawgRyder

Think of it this way...if you have any doubts about the battery/batteries replace them!!
You only have to get stuck on the side of the road out in East Broken Piston Idaho (out of cell range) at 2:00AM just once to realize how dark the night can get.
That one passing car every 4 hours will not stop to help you.
But...you saved what?....maybe $200?...good for you.
The tow truck won't cost you any more than maybe $500!
Replace the battery.
Drive the car with confidence....after all...there are only 200 - 300 more things that can go wrong...LOL.
Have fun.
Bob

Lol. That was way to specific to be made up Bob. Did you make any friends in Broken Pistol? BTW i love the name Broken Pistol Idaho. I hope it exists.

[schumicat]

if your battery was down to 3 volts I seriously doubt it can be brought back to life so that it will hold a charge.

[rick-l]

Originally Posted by tiwebber

The charger has a 6 Amp and 2 Amp setting. I used 2 Amp because I read that a slow charge would be better to reduce any sulfation. I left the charger on the first battery that had 12.3 volts (after a few minutes of without charger). It now has about 12.7 volts (after a few minutes) without charge. That's improvement!

If you put two amps in it for 16 hours it would be charged to 32 amp hours or 1/3 of capacity. See where I'm coming form here? Of course I could remember wrong and they be less than 90 amp hours.

I think the extra voltage is called a surface charge and it will disappear with a light load.

[HawgRyder]

Broken Piston is just down the road from Lost Lug Nut....have not been stuck in either one myself...but have heard rumors of them.
My real point is: if not properly maintained...the car will let you down when you need it most.
I used to work with a guy in Stelco Canada..he bragged for years about never changing his oil...just added some when it got low.
One night his daughter got sick...he rushed her towards the hospital...and never made it...the engine seized...she died in the car on a lonely back road.
He now preaches proper maintenance to everyone he meets.
Tough way to learn about reliability.
Bob

[tiwebber]

[QUOTE=rick-l;6187548]If you put two amps in it for 16 hours it would be charged to 32 amp hours or 1/3 of capacity. See where I'm coming form here? Of course I could remember wrong and they be less than 90 amp hours. QUOTE]

I see your point. I checked the specs on Interstates website and they dont report how many amp hours this battery has. I called Interstate and they say 33 amp hours on the uc 911 (which is what i have). So 16 hours is close to full charge I guess.

I did put them in the car yesterday and went for a ride in the hood. No problems. I looked at the voltage today and it 12.58 - down from 12.62 which it was at yesterday when I put them in the car. I'll go for another local drive today and see what happens. I think they are "OK" - maybe not great. I wont be visiting Broken Piston any time soon. Not really trying to flirt with disaster but rather am interested in if they really are screwed or not.

Lol, I read your note again HawgRyder - you called it Broken Piston not Broken Pistol. I want there to be a town in Idaho called Broken Pistol.