Combining multiple charging systems

[jaapbood]

After 13(!) years of good service, I’m replacing my 4 Northstar AGM serie/parallel (12V-145Ah) house batteries with 4 Hoppecke AGM (6V-250Ah) in series to get 24V.
It looks like this is also a good time to think about my 3 charging systems:
- Victron Multiplus 24V, 3000 watt (combined inverter/charger)
- Optima regulator for second 24V generator on engine
- Victron regulator for 2 solar panels (in series to get 24V)
All three are connected to the plus and minus of the battery bank. All three regulators are set to the optimal voltage to charge AGM batteries.
All 3 have nice bulk/absorb/float phases. However there is ofcourse no coummunication between the 3 regulators. So while one is “floating”, the other one comes up in “bulk”, etc. Comfusing.
Of course I can disconnect the shore power, before starting the engine (good practice I believe), but the solar panels do their work anyhow.
So my question is, how does this work out on the batteries. Is it not so that the carefull phasing of bulk,absorb and float are killed by the multiple charging currents? What to do, if anything?

[sailingabe41ds]

Hi..

I recently asked a similar question. Look up a thread titled "experts on solar panel/controller question".

Abe

[smac999]

There is nothing you can do.

If voltages are set the same in all 3 you have done the best you can. And 98% of the time it will be fine.

Generally if the batts are low all will be in bulk. If batts are full all will be in float. And if batts are near full you may have 1 in float and one in absorb. But at this time the batts are current limited so it does not matter if one charger is 20a and 1 is 0a. In different stages. Or both are 10a in same stage.

[jaapbood]

Thanks! I guess I have to live with uncertainty...

[Stu Jackson]

Originally Posted by jaapbood

Thanks! I guess I have to live with uncertainty...

It is not uncertainty, it is reality.


IIRC, Maine Sail at one time suggested that you simply change the setpoints of each of the charging sources slightly differently to avoid possible "conflicts of interest."


smac's approach is just as realistic. The batteries don't know or care. Why? Because by that time the battery acceptance has reduced and the voltage charging setpoint has been reached (i. e. ~ 14.X V) and charging has dropped out of bulk (just a different way to say current limited).


BTW, multiple charging sources are now the norm, rather than the exception.