For a small campervan I'm looking for a way to charge the household battery from both solar and alternator.
I have gathered the following components:
-Household battery: AGM super cycle 12V/60Ah
-Smart Solar MPPT 75/10
-Orion Smart Tr 12/12-30
The start and house hold batteries will share common ground. The output load will be connected through a relay to the household battery. The relay coil will be switched by the load output of the MPPT to prevent deep discharge.
According to the datasheet of the Victron AGM batteries the charge current must be limited to 0.2C (12A in this case). At higher charge currents temperature compensation is required.
I see the following potential problems:
-The Orion will bulk charge with at least 30A and the Orion can not use a temperature sensor to compensate. This will probably reduce battery life.
-The available space for the battery and the chargers is quite small. The orion will dissipate more than 50W during bulk charging which is a lot in the small compartiment.
-The high current draw from the alternator might slow down the charging time of the start battery.
The options to solve this:
-Reduce the Orion charge current but this seems not possible when looking at the settings in the App.
-Use the isolated Orion Smart Tr 12/12-18. With 18A charge current the battery might have a longer life.
-Use a DC/DC converter to feed the PV input of the MPPT and a Cyrix between the alternator and the DC/DC converter. A relay will switch between solar and DC/DC converter as source. I know some people use the Orion 12/24-5 isolated converter for this purpose. The Orion's short circuit current of 39A concerns me in combination with the MPPT spec of 13A max. As far as I understand the MPPT will short the input during the MPPT tracking cycle. An option here could be to use a diffent brand DC/DC converter with constant current limit below 13A.
Can anyone advise?