Overheating Alternators

[madmartigan]

I've got a 2023 Winnebago Travato 59GL with the Volta Pure3 system "under-hood generator" that recharges my lithium batteries while driving or parked and running the engine in a high-idle mode (1100 - 1600 rpm). I recent saw a YouTube Short with a guy talking about alternators being inefficient and generating a lot of heat.

Has anyone with a manufacturer installed secondary alternator ever had any problems with them overheating or burning up from lots of use with the engine running while parked to recharge house batteries? As far as I can tell, Winnebago expects users to use this high-idle mode while parked since they installed an auxiliary button and mode for the engine to auto-start in high-idle mode if the house lithium batteries get below 25% (with some other stipulation such as engine coolant temp and fuel level).

 

[booster]

Loaded question, to be sure, and also one with lots of opinions out there.

High output alternators can run hot, especially when pushed passed about 60% of rated output continuously. We have seen data to back up that the 12v Nations (made by XP Power engineering) alternators that rate at 270amp routinely produce about 165amps average over time when controlled by a Balmar regulator that cuts them back at about 225*F at the output connection.

The Volta is a 48v system so much lower current and much less heat per watt generated. I haven't heard of overheating with them, but would worry about belt loading and side loading of the front engine main bearing at the high end of their power range.

The manufacturers tout the hi idle charging but we haven't seen much of it in our camping locations. A van at hi idle, especially a diesel, is pretty loud and irritating so that may be part of it, and many of the campground rules apply the same hours to idling charging as they do to generators. Before the updated rules we were in a campground full of big trailers, most pulled by Ram trucks with very noisy Cummins diesel engines. The noise during the day was insanely high as everyone was keeping their trailer air conditioned and pets cool by running engine for many hours straight.

I think many users just try to lump their charging into trips to the grocery store, tourist spots, trailheads, dump station, etc. We never plug in with out 07 190P Chevy Roadtrek and the 300 watt solar covers most use if it is sunny and a quick drive takes care of the rest.

Personally, I would not want to idle my van for hours on end every day charging the batteries, but that is my opinion.

 

[madmartigan]

"The Volta is a 48v system so much lower current and much less heat per watt generated."

Great point that I hadn't considered! Thanks for your input.

I've rarely needed to use the high idle feature to recharge batteries. As you mentioned, driving around pretty well keeps them topped up even with the house A/C running.

The roughly 12kwh of capacity that I have is plenty to run the A/C all night if I'm camping somewhere that doesn't have shore power.

Thanks again. Great info.