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  #11  
Old 06-29-2010, 06:47 PM
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Default Re: Over charging

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Originally Posted by F16bmathis View Post
I should have figured it out when it took all day to charge, and the batteries were starting to get really hot.
[snip]
You just described thermal runaway. As a lead acid battery gets hotter the charge voltage goes down. This can lead to a situation where excess charging creates the heat that means the voltage applied should go down but since it doesn't the current goes up. This is excess charge so almost all the current goes into heat, which further heats the battery, further lowering the voltage and increasing the current...

Nothing good comes from this and it can destroy a battery the first time if it goes on long enough. I think you pack just died though a few of the batteries may have survived. I've actually started thermal runaway at as little as 2 amps in a tired old Optima. I think the advice to add a upper limit timer that will shut off the charger is a great idea. Once the thermal runaway starts very few charger shutoff algorithms detect the need to shut down. (systems that shut down the charger when the voltage stops rising and amp hour counting based charging will shut down thermal runaway)
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  #12  
Old 06-29-2010, 06:55 PM
F16bmathis F16bmathis is offline
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Default Re: Over charging

I had contiplated doing that, but figured it would just shut off when it was full. Even the night this happened, I got up at 2AM to close the hood, as it was going to rain soon, saw it was still charging, could've saved me a headache.

I took it to work again, 65 down the highway, made it there, but it got slow, and charged in less than 2 hours, so I checked the specific gravity and found it to need more of a charge. I guess it was really dead when I rest the charger after boiling them. I had checked it every hour during work, and kept creeping it up. Drove home at full speed all the way. Its charging now, but I know I've got to adjust it up a little more.

I'm sure I've shortened thier life, but they seem to be coming back to full power.
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  #13  
Old 06-29-2010, 06:59 PM
F16bmathis F16bmathis is offline
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Default Re: Over charging

Allrighty then, sounds like a timer is a good safety net. Too bad these didn't die, I could've justified LiFePo4's!

Thanks all.
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  #14  
Old 06-30-2010, 06:04 AM
mszhao mszhao is offline
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Default Re: Over charging

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Originally Posted by F16bmathis View Post
I didn't die, get burned or have acid splashed in my face. 144V 225 amp hour lead acid Trojans with a Zilla 1K, Warp 9" motor. All winter, the batteries were cold, and the charge was less than full. So I turned my Manzanita up some. Two days ago, I plugged it in, went to sleep and woke to smoking batteries! Normally 10 KWHz a charge that day was 70! Steam was coming from all the vents, most water was gone. I let them cool, re-watered, and reset the Manzanita for the voltage the pack was at now.

Should I be adjusting voltage of the charger? I occasionally check the batteries, but they seem about at the right voltage 6.45 +/-

Why did it keep charging, other than the charger didn't think it was fully charged yet? Should I vent the chargers heat vent out of the cab of the truck in summer?

Are my batteries shot? I did make it the 16 miles to work on the highway doing 55-65, mostly 65.
you'd better check your batteries and charger both before using them again.if the voltage of the batteries are normal now?is there any batteries defective so that it leads to overcharing? or if the batteries were over discharged when you were driving?
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  #15  
Old 06-30-2010, 01:50 PM
F16bmathis F16bmathis is offline
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Default Re: Over charging

Its day three, and I'm back to driving at full speed 14 miles to work, charging, then 14 miles home. No lagging in acceleration. I'm using the Specific Gravity thingy after the batteries are fully charged to see if they really are, and so far they are not, so I'm still slowly increasing the charger back up.

I have not found a single battery that is out of specs with any others yet, but I haven't checked them all. I first checked the ones with the lowest voltage. I gotta check my overall range sometime, see if I'm still getting the 40-60 miles.
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