Multiplus 24 3000 to trickle charge AGM battery

[Theuns (Theuns Holtzhausen)]

I have installed a MultiPlus 24 3000 running 2 x 200 Ah 24V LiFePo batteries. Truck is 12V AGM. Looking to use the trickle charger built into the Multiplus to maintain charge on truck starter batteries, but being 12V and the MultiPlus putting out 24V… Is it advisable to use a step-down converter between the MultiPlus and the truck starter batteries to take the 24V down to 12V? Not sure if the MultiPlus was built to handle such a configuration. Anyone who has done something similar with experience?

[pwfarnell]

This link explains how the trickle charger works. You could put a step down on it, or just use a separate 24V to 12V DC to DC charger. The link also raises some concerns regarding lithium as the source battery. May give you some good for thought.

How does the Multiplus trickle charger work

The trickle charger on the Mutliplus is not a true charger, it does not have a set charge voltage. It is a small circuit that is connected directly to the DC input header within the Multiplus and it contains a current limiter and a diode. The diode is to prevent the starter battery from charging the domestic battery if the domestic battery has the lower voltage. See the diagram below. This means that the trickle charge function is always active, therefore if you have solar connected to your dome…

[Theuns (Theuns Holtzhausen)]

Thank you, much appreciated for the details.