Hi there,
I have a MPPT 75/15 in a boat charging a dedicated house battery and I would like to know if I can connect the output to keep the other 2 cranking batteries charged while boat is stored.
Thanks
asked
Can I use MPPT output to charge/float battery?
If the batteries are all the same chemistry/voltage and your wiring is OK, yes. You might find the boat is already wired for this with a switch that connects start and house for boost when starter batteries are low.
Hi Kev,
Thanks for replying.
All batteries are light-deep cycles lead acid.
I have done the wiring for the solar and house batteries, I've got a two-way switch which is there only to isolate as I've added a combiner to allow charging of both batteries once the load is available.
there's an Anderson on the end of the load cable that I can connect to the batteries but I'm not sure what voltage to go for as usually they will be nearly full battery just needing topping up and floating....
@Sek There is a risk that when starting the engines, high current can flow from the house batteries to the start batteries.
A risk of blowing fuses in the mppt/wiring that is only rated to 20a.
The charger would only be connected to cranking batteries while the boat is parked.
I'm unsure if I have to set the load output of the charger to a certain voltage similar to the floating phase.
MPPT will start a charge cycle daily. This will switch to float automatically. If the boat will be left unused for long periods, it might be a good idea to set a short max absorption period in the MPPT.
