G'day Dick, me ole mate,
Sorry Dick, but car chargers, for your typical lead acid battery, will cook your typical gel cell, they charge too fast, usually at about 4 amps, that will cause gasses to accumulate in the battery and they can't vent the gas, after a while you will see the sides of the battery swelled out, & that is the end of your gell cell. That is why you should remove the caps from a lead acid battery when charging.
You need to charge em at about 500 to 800 Ma depending on the size of the gell cell. Slow is better. As Rcfury said, a Battery tender Jr is the ideal charger for your gell cells, I use one for my flight box & my Harley battery.
Hey Dick,
I'm working on my Yak 54, as I type, I will be putting an AR7000 RX in it, Spektrum for ever!!!!!!!!