Battery use and generators

[neoflyer]

I watched a webinar about solar systems on RVs. It was mentioned you can be less careful about running your batteries low if you have a generator. I wonder about this. My generator uses the house batteries for starting so you have to not let them get too low. I assume this is especially true for me since I have a diesel generator and my batteries are lithium so probably don’t supply the most cranking amps. Is my thinking correct on this?

 

[OffGridInTheCity]

I watched a webinar about solar systems on RVs. It was mentioned you can be less careful about running your batteries low if you have a generator.

This would make sense if you can start the generator without the solar batteries - e.g. my Honda EU3000is has it's own battery separate from the solar system.

I wonder about this. My generator uses the house batteries for starting so you have to not let them get too low. I assume this is especially true for me since I have a diesel generator

But yes, you're right. Common sense applies here. If you are dependent on the solar system batteries to start your generator - then you *definitely* don't want them to go below what you need to start the generator.

and my batteries are lithium so probably don’t supply the most cranking amps. Is my thinking correct on this?

This is not necessarily true. Your 'lithium' batteries will have specifications - that include max and continuous amp ratings. Compare that to the generator specs (if you can find them) OR even do some tests at home. I wouldn't assume a negative

 

[brewmatic]

I'm using small gas generator similar to this one - https://www.tractorsupply.com/tsc/p...-portable-gasoline-generator-gen1000i-1694825 as an emergency back up for my RV. It's cheap but quite useful. I'm also using it for tent camping.

 

[HRTKD]

As I recall, my on-board 5500 watt Onan gasoline generator will start at some absurd low voltage, like down to 6 volts. Of course, I would never let my batteries get that low.

With a diesel generator, the voltage may need to be higher. Check your manual.

Due to the high amp load of starting, I chose to retain a smaller lead acid battery on the tongue of my trailer for starting the generator. A couple forum members have tested starting their on-board generators (up to 5500 watt, some lower) and seen surge amps in the low 200's. My LiFePO4 setup should be able to handle that without dipping into the surge capacity of the BMS. But I chose to not take a chance.

The amp limitation is often the BMS, not the batteries.