salvage a deep cycle battery?

bmet

We just replaced a Werker 12v 185ah deep cycle battery which had intermittent performance on an electric gate. It had been connected to a 5 watt solar panel, and lasted for about 7 years uninterrupted.

My brother replaced the acid in the cells, and watched the solution bubble while it was being charged. After 24 hours, the battery was replaced back in the gate, and again it began to run down.

I don't know if my brother tried to do anything else with the battery, but it was stowed in the car port. I put a meter on it, and it read 8.5 volts. Because of it's weight, I used a child's wagon to move it over to the junk pile, but when I metered it again and suddenly it read 12.6 volts. My curiosity got the best of me, and I put my POS inverter on it, and it ran a couple of minutes before the inverter shut off. The voltage was back down to 8.5v

Is there a guideline to determine if the battery can be salvaged or does it's behavior spell the end of its road? Thank you.

Cariboocoot

Re: salvage a deep cycle battery?

I'm glad you posted that: we can point to it anytime we're trying to explain the end result of a sulphated battery. It's got the Voltage, but not the Amp hours. It's scrap metal. If you could look inside you'd see most of the plate surface is choked off with deposited sulphur. Turns a 185 Amp hour battery into an 'AAA' cell!

It's amazing it lasted as long as it did considering how small the panel is. 5 Watts? Are you sure? That wouldn't even keep ahead of the self-discharge rate - especially as the battery aged. Any other charge source like a "back up" AC transformer?

bmet

Re: salvage a deep cycle battery?

Yes, it's a 5 watt panel, verified by the contractor whom originally installed the gate for us. There is no other source, just the panel. The gate's location is a lonely stretch of country backroad

When my brother had looked into the cells, he said the electrolyte had dried up. I guess we wasted the acid for nothing.

Thank you for the confirmation of the scrap heap. It'll be returned for recycling to the retailer.

niel

Re: salvage a deep cycle battery?

from the sounds of this it was also not regulated, that is-no controller. i keep telling everybody that a small pv can cook a large battery given enough time. with enough periods of non-use time it reaches its full charge and then the rest is overcharge. 1> i recommend you change the battery and maybe make it a tad smaller depending on its draw and worst case usages. 2> add enough pv to at least have a current output that is about 4-10% of the ah rating of the battery. normal recommendations would fall between 5% and 13%, but you can get away with it being lower with enough recovery time periods that it's not used. being it lasted 7yrs then maybe you'd even get away with 3%, but that's pushing it imho. finally 3> i highly recommend the use of a controller to prevent ruining the battery through overcharge. this can be a cheap pwm, of the proper current rating, if you like and is recommended for a small setup such as this. you may need a weatherproof enclosure that can vent some of the heat if you don't already have one there and maybe a fuse.

RRRAAAYYY2

Re: salvage a deep cycle battery?

Any time a battery plates sees air, it becomes junk. The carbon dioxide in the air causes it to corrode. Which I think is different than the sulfate, as the sulfate you can sometimes get to "react" off the plates. The corrosion is death to the palte.