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Greetings,

Right around this time last year I had a couple of upgrades installed to the Magnum inverter/charger system in my coach: a battery monitoring system (BMS) and an auto generator start (AGS). Both have been performing as intended; when the house batteries drop to a certain voltage, the generator starts and the inverter/charger does its thing (it freaked out the guys down at the RV repair shop recently when it started the generator as they were working on the coach, heh, heh).

Anyway, fun times aside, my question for those who may have a similar setup is this: what voltage and/or percentage of full charge settings are you using to tell the generator when to start up and shut down? So far, I'm mildly aggressive in that I don't let the voltage drop below 12.2V before starting, and the shutoff setting is when the batteries register greater than 95% charge. The typical result is that when not plugged into utility pedestal power, the generator runs about once a day in the summer, and sometimes multiple times a day in the winter. Good exercise for the generator, but possibly not very efficient. As a side note, the house batteries are 6V AGM deep cycle, two series pairs wired in parallel, roughly three years old.

Cheers,

Brian,

Is your BMS a magnum brand product that can work with the Magnum inverter?
I assume the BMS gets its info from a shunt placed on the battery bank negative side?

If your BMS is a magnum brand like your inverter, then you are better off setting the generator start to turn on by percent capacity remaining in the battery bank. Using voltage to start the generator is not ideal, as you tend to get voltage drop under load, which will prematurely start the generator.
Depending on how conservative you want to be with your batteries, I would suggest somewhere 50% or above, 60 to 70% state of charge is a good compromise of being gentle on the batteries without needing to run the generator too often...
If you boondock a lot, be sure to charge to 100% at least once a week. Also make sure you charge parameters are set to the brand and type of batteries you have. That is bulk, absorb, and float voltages.

Do you have solar on the roof???

What all do you run off of these batteries and how long do they last before they need to be recharged?

Dumb question. In looking at the Dual Pro there are different charging bank options. Would assume each bank/battery?