Multiple charger one slave?

Hi,
I’m not “electrical beginner” but “solar/offgrid/ongrid/campervan” beginner
there are lot of tutorial explaining how to setup a simple “main battery / service battery” with solar and alternator and sometime AC/DC charger… but I need to understand more in depth how systems will interact before doing something (stupid :sweat_smile: )

here is my “coarse” setup :

  • 2 solar panels in 2 arrays (I don’t want that one solar panel shutdown the whole setup if a shadow cast on it)
  • an AC/DC power source 110V/220V
  • alternator charging
  • 1 main battery, 2 independant service batteries
  • DC/AC inverter

so my biggest issue is “if there are many masters and a slave, the slave will die”

  • I will have 2 MPPT since I have 2 arrays, the 2 MPPT are masters (they have charge algorithm)
  • I will have a DC/DC charger, for the alternator, so a 3rd master…
  • I will have a AC/DC charger when I can have ongrid power

I want that the solar panels can work in all conditions : when connected ongrid, when driving, when offgrid standby.

then I want to have unbalanced parallel service batteries : I want to be able to change the batteries independently, don’t want to have the weakest batterie limit the other battery… and dont want all the issues when doing dumb setup (either serial batteries [ one dead = all dead, one limit = all limited, first memory affected stop all charging…] or parallel batteries [need balanced batteries, one limit = all limited, shared memory effect]

  1. how will the 2 MPPT will “share” the charging algorithm state? (off grid case)
  2. how will the 2 MPPT and DC/DC charger will “share” the charging algorithm state? (sunny driving case) (and how can I manage priority? for example at start of travel I want as much as possible to charge using solar, but when reaching the standby location, will want to finish the charging with alternator, or when offgrid with low battery, might want to use the alternator to charge on low sunny conditions…)
  3. how will the 2 MPTT and AC/DC charger will “share” the charging algorithm state? (on grid sunny case) and how can I give more priority to solar?
  4. how will all the chargers “know” what to charge? (one battery can be at 75% of memory state, while the other aged better and is only at 20% of memory state…)

what disturb me is that for me I would have designed the stuff like this :

  • a DC/DC that gives a “bus” voltage from the alternator
  • an AC/DC that gives the same “bus” voltage from the grid
  • several MPPT that optimise the solar energy (a MPTT is mainly a system that will try to find the best power point, eg try to suck the most amperes and stop when voltage drop and then try to stay on the horizontal part of the I/V curve of the solar panel, so it’s in fact a DC/DC with power adjustment) that gives again the same “bus” voltage
  • several batteries charger that “consume the power” from the bus, and then might take 10A from the MPPT, 4A from the DC/DC… and manage (REALLY manage, the battery, not just look at over current, low charge and heat protections, but also charge, charge history…)
  • battery consumers : DC/AC, onboard DC bus (so DC/DC)

and this will be easier to integrate 3rd parties, because the AC/DC from victron are only 600W max, and what if I want to use power consuming devices when ongrid (without having to create 2 circuits)
at first I looked to easysolar II gx product, but it’s for residential : only 220V input, not 110V (and on a camper van, you don’t know the voltage you’ll have) and only one battery and no alternator input… and a bit big for a campervan setup (I prefer small, dedicated, devices that I can change/disconnect if defective)

thanks in advance for all the explanations :slight_smile:

Off grid each mppt charge controller will follow its own charge algorithm.

Use wind solar priority or conditional ac connect for off grid and mobile.