VRLA.. Valve Regulated Lead Acid battery problems...

[Blagadan]

Hi Guys,

The battery on my lawn mower no longer has the capacity to start the engine. The battery reads 11.7volts as it sits. It is a sealed battery so I dont hold much hope for it. I tried to recharge it but after a day or two it drops back under 12volts. Having googled Valve Regulated Lead Acid batteries it seems that you can rehydrate sealed batteries? Is this true and if so is it just a matter of topping the cells with demineralised water and recharging as you would do with a regular wet cell battery.... Or is there a special catalyst required to rehydrate them?

thanks,

B

 

[srjones]

I'll be interested to find out if anyone knows. The only thing I could find was that it (rehydration) could be done and it saves money. However, I didn't find anything around how it was done.

I have a chance to get some big VRLAs from a UPS and I'd like to keep them going as long as possible.

-srj

 

[Blagadan]

Out of curiosity, I pryed the top cover off the battery. Removing the cover revealed 6 soft rubber caps. When i removed the caps, I could see down into each cell. There appears to be a white fabric like material in there. Looks like woven fibreglass.

A little more digging on the web and I found some more info about VRLA's but not specific. A lot of guys saying you can rehydrate sealed batts, but no details on how... yet.

 

[tbenn7362]

Hi,
You can refill a battery however allowing the plates to dry out has caused oxidation which destroys battery capacity. You need a new battery!

 

[Ray_Fort_White]

Most high quality new batteries are AGM - Absorbed Glass Mat - a sponge between plates. They last longer, self-discharge more slowly, and are less affected by vibration. Look at the Odyssey Battert as an example.

 

[Blagadan]

I came across this info sheet that seems to be close to what I was looking for.

http://www.oddmix.com/tech/pdf/pc_rejuvenate_gelcell_2.pdf

I know the info is for gel cell batteries but I have nothing to loose as my battery is most likely a gonner anyway so I wetted each cell with 20cc's of demineralised water. The battery is now on a low amp charge for the next few hours. I'll keep an eye on it just to make sure it doesnt overheat or do something bad !

I'll let you guys know how I get on. Time will tell I guess.

 

[Blagadan]

It charged up fine. After about 6 hours of 5amp, 14.5v charge, my charger went into standby and indicated a good result. I disconnected the batter and let it settle down. Now, 24 hours later, it is holding steady at 12.78v.

Over the next few days I'll keep monitoring it to see if it holds its charge.

So far so good.

 

[Blagadan]

I wanted to update this thread. It has been almost 2 weeks since I rehydrated my dry cell battery. I checked it again this morning and the battery was holding steady at 12.61v. The mower cranked over fine and started right up with no problems. It would appear this procedure worked for reviving my VRLA battery.

I am interested to see how it lasts over the coming season, but for now, it appears I have a good result.

 

[Soundguy]

pretty much what I expected... it was low on fluid.. and is now working once you added fluid.

had it went bone dry.. I think it would have been a gonner.

soundguy