[Elecraft] 12V Gel Cell

[John R. Lonigro]

Fred:
After all of this charging, has the voltage of the battery risen at all 
or is it still 6.2 volts?  If it hasn't risen much, I'm thinking 3 of 
your cells might be shorted out and you might be out of luck.  Like a 
car battery, a 12V gelcell has 6 cells in series.  6.2 volts sounds 
suspiciously like the voltage of 3 of them.  If 3 cells are shorted, you 
are effectively overcharging the 3 remaining good cells.

As an example, PowerSonic recommends a maximum charge current of 3.6A 
for a battery the size of yours, until the voltage reaches 14.5 volts.  
4.5A or 9A is too much!  Then you are supposed to switch to a constant 
voltage supply and watch the current decrease until it is about 120 ma.  
Also, their charts show a battery is considered discharged when the 
voltage gets down to about 10.2 volts.  Unless someone knows some 
battery restoring tricks, yours might be hosed.  Good luck and 73's,

John AA0VE

Fred Jensen wrote:

> Without intending to, I allowed the 12V sealed gel cell 12 Ah battery 
> to dischage to about 6.2V when I finally discovered it after coming 
> home from a trip.  It was slowly being discharged, not open circuited.
>
> I started charging it through a light bulb, and then directly from a 
> 13V voltage regulated supply.  Charging current began at about 1A and 
> rose to 9A when I stopped it, and put the battery outside in the 
> cold.  It wasn't hot but was warmer than when I started.
>