i have 2 7.5 amp 12volt gel cell batterys, how big or small of a charger do i need to charge them? what should the charge voltage be? i have several 12 volt power suplys that put out 500 mA, and was wondering if it should be more than 12 volts? like our trucks charge the batterys at 14, should these be charged at 14 as well?

 

7.5 amp? These must be for a small power tool or something?

Anyhow, larger gell cells used to be used in RV's and stuff. Charging current has to be limited to like 1/20th their rated amp hour or less, or the gell will bubble away from the plates and the battery's capacity will be reduced. They also need to be charged at lower voltage than flooded cell batteries.

AGM's have become way more popular as a maintance free starting or deep cycle battery. They charge at the same rate and voltage as a flooded cell would.