If you have Interstate GC batteries in your RV you could be slowly destroying them!

I replaced interstate batteries and tried to figure out the correct voltages for charging (Absorption, Float and Equilization).It was ALOT harder than it should have been as it is not listed on their website? I called and talked to 4 people before getting a call back with their recommendations! Interstate GC Batteries need 15.3v for Absorption, 13.2v for Float and 15.6v Equilization.

The Problem

On this particular RV they had a Progressive Dynamics converter and it would put out 13.6v. Unfourtunaley the battery was only getting 13.1-13.2v! There is about 20-25’ of wire between the converter and the batteries which explains the voltage drop. It is critical to measure the changing voltage at the battery with a voltmeter to make sure you are charging it correctly. I would estimate that at the battery at 80% SOC if it could only get 13.2v. Over time the lead plates will get covered with sulfate and would continually reduce capacity of the battery.

Every lead acid battery will need to be completely full at least once a week to help keep the lead plates from sulfating. Some batteries will also need to be equaled about once a month as well.