battery rejuvination question

[mutant]

i have a 48v cart that has some tired batteries- i was told by a friend if i stuck each battery on a high amp short charge-(10 to 15min) it would boil off the oxidation on the plates extending the usefulness of the batteries...

i think that is bunk,but i wanted to run it by you guys and see if there is any truth to this.

[radioman]

I wouldn't do it. Batteries may explode. If you want to try go ahead. I have seen small batteries brought back to life by heavy charging but they really never fully recover. A lot of hHydrogen gas is generated during this type charging may cause battery to explode if there is a bad internal or external connections causing a spark.

[Volt_Ampere]

The stuff on the plates is sulfation not oxidation. You may get a slight improvement from heavy charge / discharge but if it is severe, it is very hard to get an improvement. There are some gizmos out there that are supposed to reverse the sulphation process but they take weeks or months to do the job on a badly sulphated battery.

[Yamahaman]

How old are these batteries and if you decide to do this unplug the charger from the power source before taking the cable off the battery to prevent a spark.

[JohnnieB]

The at-rest voltage voltage for a 48V battery pack at 100% SoC (State of Charge) is about 50.9V and if your battery pack's voltage is significantly lower than that when measured about 12 hours after the charger shuts off automatically, deliberate overcharging can (maybe) get them to stabilize at a higher at-rest voltage. However, it does not actually recover the storage capacity lost in the normal and unavoidable aging process. It simply allows better access to whatever storage capacity that is still remaining.

Hitting the batteries with a lot of amps for a short period of time as your friend suggested, could easily destroy the batteries, but a series of back-to-back charges with your regular 48V charger might produce some improvement without the associated dangers.

By back-to-back charging, I means initiating a new charge cycle without driving the cart after it was charged, or after a very short trip. Basically your are recharging supposedly "fully" charged batteries. (This is also a way to do an "Equalization" Charge when the individual battery voltages vary from battery to battery within the pack.)

The 18 month old T-105 batteries that were in my cart when I bought it, would only charge to 85% SoC and after a couple weeks of back-to-back charges with a Powerwise II, they would charge to 95% SoC. By the next summer, they were charging to about 98% SoC and they were charging to nearly 100% SoC when I upgraded to a 42V battery pack with all new batteries.

Again, I'd like to reiterate, back-to-back charging does not regain the battery's storage capacity, it only improves the access to the storage capacity that still remains after the normal aging process has taken its toll.

[mutant]

thanks for all your input guys-JonnieB i hear you clearly and it seems like very little gain for the risk...the batteries age is unknown-the cart was donated to the school and the batteries look like a wet cardboard-kinda wiggly as if the lead has grown-cant be good and i see a total replacement in the future....the cart is a yamaha 22g.
it is a good cart but i LOVE my EZ-GO!