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Michael Connolly avatar image
Michael Connolly asked

24v LA starter batteries and 12v Lithium House charging

Hi all

Motorhome setup includes 400ah house Lithium setup, three Mppt 100/30 with 1.6kw solar and a genset . The truck starter is a 24v (two 12v) lead acid batteries which is charged via alternator.

I would like to top up charge my Hpuse batteries while driving from A to B but do not want to connect the alternator to the Lithium batteries (via charger). Instead I want to use the 24v starter batteries as a source for charging the Lithiums.

I believe that what I need is...

Solenoid connected to ignition to ensure charging only when ignition is on (alternator running)

VSR to protect the starter batteries from being drained too much

A MPPT 100/30 to feed the 24v starter battery power(via the solenoid and the BSR) to the Lithium house batteries using the same lithium charge profile I use from the solar panels.

Is this a workable solution AND what Victron products will do this for me.

Thanks

Mick

victron products
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1 Answer
JohnC avatar image
JohnC answered ·

There's probably a few ways you could approach this Mick. Possibly the simplest is just to accept a 'Float' V from your 24V system with a Victron Orion. Ie. not a full charge profile.

There's a helluva range of em, and what you choose may depend on what your alternator can do, so it doesn't drain the 24V batts even when the engine is running.

https://www.victronenergy.com/dc-dc-converters

Maybe one'o'these: https://www.victronenergy.com/upload/documents/Datasheet-Orion-DC-DC-converters-high-power,-non-isolated-EN.pdf which also mentions an engine switch.

The A ratings refer to the 12V side.

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Michael Connolly avatar image Michael Connolly commented ·

Thanks for your reply. I have an item like this already, it’s a Redarc CE40-13.8 which is a similar item. I wanted to use a lithium profile and I happen to have a spare MPPT 100/30 that I can use for that. Do you have an idea for a VSR for the job?

Again thanks

Mick

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