Different MPPT absorption rates

Q&A and troubleshooting
, ,
1

morning everyone,
Hopefully a quick q please.
I have 2 MPPT chargers attached to a multiplus 12/3000 and 4 x 110 Ah Victron 12v batteries. The small one is a 75/15 with 2 small 80W 18V panels, and the large is a mppt 150 70 with 2x 405W 24V panels.

Our batteries are not at 100% full, and the smaller MPPT will happily bring in as much wattage as it can, but the larger MPPT sits at 0.1A.

My question is this - what is the mechanism/logic/setting that results in the larger MPPT (with larger panels) providing a disproportionally tiny power input into the system and can it be dynamic?

Images taken roughly at the same time.
Learning lots here, and grateful for all comments & views.

thanks
Martin

all
all627×1393 141 KB

small
small627×1393 115 KB

large
large627×1393 95.4 KB

2

I had a similar problem with my two different mppt’s.
Try disabling charging in the mppt 75/15 settings, leave it 30mins or so and see if the 150/70 takes over the charging.
if it does then you could try reducing the absorbtion voltage of the 75/15 by 0.1v to prioritise the 170/50. that worked for me.
enabling dvcc in your cerbo if not allready enabled might also help.
disabling any bluetooth networking between the two mppt’s might also help.