Run AC's from Inverters or not

[cmillsap]

(06-08-2017 13:01)davidbrady Wrote:  I've always enjoyed the ability to power cruisairs and roof airs via my Trace SW inverters powered by the engine driven alternator. My cruisairs need around 2kW of power each; the engine driven Delco Remy 50DN alternator is good for 7kW continuous. At 24V the draw is 80A per cruisair which to me doesn't appear to be a strain on the venerable 50DN. When traveling in moderate climates I'll often run up to two cruisairs off the alternator/inverters, one on each inverter. The 50DN is rated at 300A continuous duty and the inverters are known to run 7x24 for 15 years or more without failure in off-grid installations. In hot, hot weather I'll run the generator and four cruisairs but when I pull into a CG I often kill two cruisairs and turn off the generator. My inverters quickly and seamlessly transfer power over to the batteries. (Or, I can let the Vantare Power Management automatically prune two cruisairs). When I connect shore power the inverters seamlessly transfer power to shore all with nary a hiccup from the cruisairs. I enjoy the flexibility, redundancy, and seamlessness of this approach. What's your opinion on running air conditioners from the inverters?

David,

I often run two roof A/Cs off the inverter. The bath/bedroom unit and the salon unit are wired to run off the inverters. The Inverter DC amps display shows about a 65 to 75 amps load. The inverters will stay on bulk charge while the two air conditioners run while we are traveling even if the generator is running. Apparently, the 50 DN alternator (when running) has priority over the generator and it feeds the inverter/chargers which keeps the energy replaced in the batteries. That tells me that the 2 A/C units pull a lot of power out of the batteries and the inverter/chargers must work hard at continually bulk charging the batteries. When parked (50Dn not running) all A/C units evidently run off the generator power or shore power as the charge rate of the batteries go to float quickly.

So, it appears, at least on my bus and while traveling, that regardless of whether I run the generator or not, 2 A/C units run off the inverters. With 3 A/Cs running the generator load runs about 3 to 15 amps which is about the load required to run one A/C unit.

I'm going to ask Marathon if in fact the A/C units are wired this way when I'm there later this summer