So I have a 75|15 charge controller which currently charges my LifePO4 house battery from solar. But my AGM starter batteries have no charging when I’m off grid, except from alternator which is used sporadically, yet the AGMs get used daily for anchor lighting. So sometimes the AGMs take a beating a…

Just connect the VSR between the two batteries with the sense side on the LFP. The cables should be 16mm or thereabouts enough to take the full solar output and a bit more. The VSR is just a switch so can’t as such overload the alternator, however to stop the LFP running the alternator hard just p…

MPPT 75|15 Load Output to Charge LifePO4 Battery

DIY

jrmartin505 2 September 2025 19:00 21

Still looking for a reliable way to limit the amps to the VSR, but I guess technically that’s another topic so I’ll start another thread.

Thanks everyone for all the helpful feedback

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MPPT 75|15 Load Output to Charge LifePO4 Battery

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