Adding more batteries
Good Afternoon all! Fully charged my 2 x 6v batteries in my class A work well and provide me 208AH (104 usable). I have 300 watts of solar that works great in the summer to keep me going however in...
Forum Discussion
jeremywatco wrote:
Thanks for the input. When I get back I'll get the batteries on the charger for a week then Pull them and test with hydrometer. While out I'll test the voltages at the converter. The converter sounds like what you describe to be normal operation. I guess I was hoping for a more bulk charging operation so when parked in shade I don't need to run genset for 5-6 hrs.
The Boondocker/PowerMax standard charging profile is not best suited for generator recharging because it drops to 13.6 for its "absorption" time instead of staying at 14.6 for a while so the amps stay higher even while they are tapering. (it would be fine if the batts are low in the morning and you do a shot of generator then go to solar for the rest of the day. But usually on solar you only get down to maybe 75% SOC overnight, so you are already higher than where that converter will stay at 14.6)
Iota is the same except it only drops to 14.2 instead of 13.6, so the amps are higher than with the PowerMax in Absorption, but still lower than they would be at 14.6 or so.
PDs will stay at 14.4 for four hours when you use the Charge Wizard, so that is much better, although the amps are not as high as you should get due to a weakness in the PD design which makes the amps taper more.
The PowerMax Adjustable Voltage models are perfect for generator charging because you just set your voltage and it stays there till you change it, so now you stay at 14.8 (say) for the whole absorption stage (or on generator, for the whole time you leave that running doing a 50-80 or 50-90.) and get the fastest possible recharge.
However, if you don't want a manual system, you would be better off with the PD and Charge Wizard, but get a bigger amp size to make up for the lower amps they do for their rated amps size.
Other adjustable voltage chargers will work too, as well as many chargers in inverter/charger units of various brands. Vector portable chargers are good at this also.
There is no simple one solution that works for everyone. (I use an adjustable voltage PowerMax for generator 50-90s and the simple 13.8v Parallax 7355 that came with the trailer for when on shore power. I could also choose to just dial down the PowerMax to 13.6 when on shore power, and ignore the 7355.)
Each RVer has to pick his own way to handle the problem.
