Thor Forums

[Chance]

I was curious about the extent of added weight so I did some checking.

Added weight with 8 AGM batteries like the E-Trek uses can indeed affect the coach's cargo carrying capacity. With more expensive lithium batteries the difference seems insignificant for the most part.

The 6-Volt 200AH AGM batteries weigh between 60 and 65 pounds each, for a total weight of around 500 pounds. This adds about 350 pounds to coach compared to a 4,000 watt gasoline Onan.

These would have a total capacity of 9,600 watt-hours, of which roughly half is useable to keep from damaging the batteries. Hence about 4,800 watt-hours are available.

Since lithium batteries can be discharged down to 20%, in order to have the same 4,800 watt-hours of available energy, installed capacity would need to be 6,000 watt-hours.

Using specs and prices for RV deep-cycle lithium batteries I can find, 6,000 watt-hours would weigh about 140 pounds and cost just under $5,000. Cost is roughly twice that of using AGM batteries if of well-known brand.

So it seems that to replicate the E-Trek system it either adds weight or cost. That's not to say that the same amount of battery capacity is needed depending on individual usage.

If/when lithium batteries come down in price as Tesla has predicted, then both weight and costs will be comparable to a conventional generator. Then it would come down mostly to which works best for our individual needs.