[Richard]

I have made some upgrades to the coach to provide full sine wave and to gain the ability to program the charge profile I want to the charger to accommodate the LiPo batteries. I am going to add a bunch of detail on what I have done, because I suspect that other RV guys wanting to do a LiPo conversion will be searching for RV specific info.

As a starting point 4 1000aH 3v cells are installed in series to provide a nominal 13v 1000aH battery bank. The bank is installed with a Housepower MiniBMS with one contactor installed on the positive side for both load and charge. A Junsi cell logger is also installed to provide easy reference to cell voltages. The Junsi is not used to alarm or trigger any relays at this time.

I installed a Magnum full sine 2800 watt inverter charger with the Magnum ME-ARC and Battery Monitor Kit. The ME-ARC gives a tremendous amount of flexibility in setting up charge profiles. I have chosen a Custom Profile with the following specifics. Charge voltage 13.8 volts. Maximum charge amperage 200 A. The charge can be set to cut off on State of Charge. Right now I have the charge ending at 90% SOC. I have the charger set to Silent, when the charge is through, therefore there is no float voltage. The charger is set to come back on at 13.0 volts. I have the inverter cutoff voltage set at 12.4 volts. With the charge to 90% SOC and recharge at 13.0, I am operating the system between 30 and 90 % depth of discharge, and each cycle produces around 600 amp hours.

I am not worrying with the alternator setup at this time. I have the coach wired so that the alternator does not charge the house batteries UNLESS I manually activate a merge solenoid. I think this is a great setup for an RV since I don't have to worry about mixing the chassis lead acids and the house LiPo's in a charging scheme. But, in case of need I can easily charge the LiPos with the alternator in a pinch.

My thinking is two fold in these settings. One, the charger is setup to operate well within the high and low cutoffs in the Battery Management system. I prefer to think of the BMS as the insurance policy for the battery bank. Two, there is speculation that operating the bank in the middle of the Depth of Discharge (DOD) prolongs the life of the battery.

None of this is going to mean beans to those who aren't interested in the battery technology. What I have learned in playing with this would have gone a long way to maximizing the AGM batteries I did have. There is a future guru seminar in Batteries at the next rally that will help all with managing the battery bank, the second most expensive maintenance item next to tires. I learned an expression that I like. Batterys don't die, they are murdered.