Recovering deeply discharged battery pack

[pcbcart]

My Powerwise QE charger (yeah, I know), bit the dust while I had it on my cart at the beach house. Problem is, we hadn't been down for a few months. So the pack was dead as a hammer. The headlights wouldn't even burn.

This is a 36 v cart. 6 6V Trojans.

I didn't have my meter or any option to get a new charger during this last brief visit, but I did take a 12 V charger and charge them two at a time for several hours each just to try and get them up off the "floor" charge wise. At least in the case of the two across which the headlights are connected, they came back up enough to burn the lights brightly.

When I go back down, I'll be taking a new DPI Accusense charger and my multimeter.

What's the likelihood of me recovering this pack? How much (and how long) of a deep discharge can a deep cycle battery handle? I'm assuming I should try and get them up as close to the same voltage as possible (using the 12 V charger) before trying to use the DPI charger.

Any other tips or tricks I should try?

Thanks

[JohnnieB]

You may have a better chance of winning the Power-Ball lottery than recovering those batteries, but if you want to have a go at it:

Try to get all the batteries up to about the same voltage, two at a time with the 12V charger. Anything above 6V is probably fine, but equal is more important.

The DPI will use a low current charge to get the on-charge pack voltage up to a factory pre-determined voltage before it goes into its normal charge cycle. If that voltage isn't reached in about 5 hours, it will generate an "Excessive Discharge" error code. IF it does, charge some more with the 12V charger in pairs, or disconnect/reconnect the DPI and give it another chance.


If and when the DPI finishes its regular charge cycle and goes into float charge, disconnect it, wait a few minutes and then reconnect it, starting a new charge cycle.

Do that several times. After the first charge cycle, the subsequent ones will take less time.


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The bad news is, even if the battery voltage does go up to 100% SoC, your battery's storage capacity has been severely diminished by sitting for a long period of time in a partially or completely discharged state.

The SoC (State of Charge) voltage is the same for a 10AH battery and a 10,000AH battery. So if your batteries were 225AH they may now be 50AH. They will charge fully, but have little, if any, run-time.

[jdunmyer]

I'll add that it sometimes helps to discharge the batteries slightly between charges. The simplest explanation is to follow the break-in procedure that ScottyB has on his site: http://www.cartsunlimited.net/battery-break-in-.html Personally, I'd repeat this charge/discharge cycle just a few times and see if the pack recovers at all.

[johnny reb]

i am sure some will disagree but i put epsom salt in all my older batteries. i bought a gas harley cart the guy threw in a 12 volt battery saying it wont hold a charge i put the salt to it shook it and charged it. it holds a charge for weeks. i am going to use it for my winch to pull other carts on the trailer. my dads cart was a basket case aka dead as a door nail when we got it i put the epsom salt to it it will set at or above 37 volts for weeks. even with him taking his dog for a ride around the building a few times. you tube has videos

not to beat a dead horse but i did the Epson salt trick and it lasted a year before i traded them in

[pcbcart]

Thanks for the input. I'll see what I can get back from a few charge/discharge cycles, and if it's not much, I'll give the Epson salts thing a try. If the batteries are toast anyway, it's not like I can hurt them.

[johnny reb]

its cheap i use a table spoon per cell. mix with hot distilled water till liquid them put 2-3 tablespoons per cell. i have added all of it evenly on batteries that had water below the plates on one of the carts i traded for. it is still running i use it almost everyday as a beat around cart. i charge it about once a week. they will die one day though