banner
bar

The following article was written by Graham VK4SR

goat2

MYTHBUSTING: GEL BATTERIES

bar

 

 

 

 

MYTH: When you overcharge Gel Batteries they explode or leak electrolyte excessively.

You could get MYTH BUSTERS to "Confirm" or "Bust" this myth or take my experience and decide for yourself.

SITUATION - 3000VA UPS containing 16 batteries rated at 12V 7Ah sealed Gel Battery

TRIGGER - to cause Battery Charger to fail to a full charge with no regulation was the failure of a 11kV lightning arrestor which caused the fuse on one phase of a two phase supply to a pole mounted transformer to blow.  A second effect of the arrestor failure was that it provided a path to earth which allowed the transformer to give an output of approximately one third normal supply volts.

CONSEQUENCE - At first there was no indication that there was a problem with the UPS except it was noted that it seemed to be operating at a higher temperature than normal and the fan was coping with this situation.  The temperature at the top of the box was only a few degrees above normal but checking the temperature at the bottom revealed that the batteries were too hot to handle.

After a few days it was noted that there seemed to be an unusual smell that was difficult to trace as it filled the room when it had been closed for a while. 

Next, it was noted that when it switched over to UPS battery backup that run time was considerably shortened and eventually the UPS went to Fault condition.

INSPECTION   - A voltage check of the batteries revealed that the normal 200V battery bank was about 50V and that all batteries would have to be replaced.  Normally it is an easy process to remove batteries but I soon found out that the heat had affected the batteries that they had fused to become one big block and that the cases had bulges that conformed to fill the spaces surrounding them. 

REMOVAL - To remove the batteries it was first necessary to separate them from the adjacent cell by use of a hammer and screwdriver to release the bonds and the try to remove then one at a time.  As the cells were now larger than the access space it meant that the only way to do this was by brute force.  This was achieved with a hammer and a block of wood.  My concern was that I might spill electrolyte and make cleanup difficult but I had no need to worry as every cell had totally dried out with the excessive charging. 

 

 

 

Please click on these small images to see a larger photo

battery
battery1
battery2

goat4

What are these goats all about?

Wise old billygoat teaching the young ones

PHOTOS  - Note the bulging of the cases as the electrolyte overheated and gas distorted the case.

In one photo it is clearly seen that the case melted and left a hole. 

Have a close look and you can see a negative image of the printing from one battery imprinted on another.

Graham Scott VK4SR

 

 

A quick internet search found these Battery related sites: Ecozen and DC Battery.com

If you know of any other links which could add useful information to this article - please alert the webmaster

Grandpa Billygoat has become the symbol for Club-Member Help pages.

The young 'kid' at the top? - He's rushing about, looking for answers - which we hope he'll find here.

If you have any updates or link info please contact: email

logo
bar