Charging House Lithium Batteries with Bus Alternator

[Glennman]

In a previous post, jozef mentioned that he has a system (I believe he said a Sterling battery to battery charger, but I could be wrong on that) where he is able to charge his lithium batteries from his bus alternator, and that it is limited to 35 amps (I am unable to post private messages for some reason, otherwise I would ask him directly). Where on the bus would a device like that be connected to in order to get such a charge? At the alternator, in the battery compartment??? Thanks in advance for any replies!

[richard5933]

I've got one of the Sterling 24v-to-12v battery-to-battery chargers. They certainly can be set for a lithium charging parameter.

Mine is mounted in the electrical bay near all my other gear like the inverter and solar charge controller. All you need to power it is an appropriately sized conductor running from the 24v battery bank to the Sterling, and then another appropriately sized conductor going to your house batteries. Mine will pull up to 35 amps from the 24v system and spit out up to 70 amps to the 12v house batteries.

You can set the Sterling up to charge whenever the bus's alternator is making power, but I set mine up to work on a manual switch. There are times I don't want to have it running, such as when I leave a campground and know that my batteries are fully charged. Like many multi-stage chargers, the Sterling will start at the bulk charging voltage and stay there for a while in the first stage, taking a while to reconcile itself with the actual state of charge of my batteries. But, when I've been boondocking I will turn it on right away as I start up the bus and by the time we're at the next stop the batteries are charged (or nearly so). Very helpful system.

[freds]

I have it on hand but have yet to wire it in is a 24V to 48V 1800W converter which I plan to feed to one of my solar charge controller in parallel with a smaller group of solar panels.

I have had fairly good luck with multiple server power supplies converted to floating ground wired in series as a solar simulator, so I am thinking that this might work.

Again not some I yet have experience with...

Obviously the solar charge controllers know how to properly charge a battery...

[windtrader]

Calcuate the charge current range for the battery pack. .5C is a safe rate. Make sure to check the specs before going to 1C and think alot and smart if going over 1C as most packs build for our use are not high charge rated.

[Glennman]

Thanks everyone. I'm getting closer to the installation of my electrical system. Greatly appreciated.