question

alain24 avatar image
alain24 asked

Connecting an AGM battery to a MPPT controller.

Greetings,


I am thinking of having some solar panels going to a Victron MPPT 75/10 or/15 to two 12V 200A lifePo4 Victron batteries, at 24V.
I would like to incorporate the starting AGM battery to this system.

Can I connect the AGM to the MPPT controller so when the AGM is charged by the alternator the MPPT would see it as a charging device (like solar) and feed the 24V lifo, preventing the alternator from frying-up if I was connecting it directly to the lifo?

Thanks

a.



AGM Battery
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

pwfarnell avatar image pwfarnell commented ·
Moved to questions and answers
0 Likes 0 ·
1 Answer
pwfarnell avatar image
pwfarnell answered ·

You do not state what voltage your starter battery or alternator run at.

Regardless of this, I would not connect the alternator to the MPPT input.

What you need between the starter AGM battery and the Lithium batteries is a DC to DC charger, look up the Victron Orion range. If you have a 12V starter then you will need a 12/24V unit otherwise a 24/24V unit.

You will also need a BMS if you are using the Smart batteries but not for the SuperPack ones.

3 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

kevgermany avatar image kevgermany ♦♦ commented ·
@Alain24

Also check if you need a bms

1 Like 1 ·
alain24 avatar image alain24 commented ·

Hello
pwfarnell ,

Thank you for the answer. Yes the original design is with a 12/24 dc2dc charger. I might stick with that configuration. It seems to be a shame not to use the MPPT unit for more than just a solar array.

Cheers,

a.


0 Likes 0 ·
pwfarnell avatar image pwfarnell alain24 commented ·
The MPPT will not take in a 12V source and charge a 24V battery, the voltage input needs to be at least 5V higher than the output voltage to start the MPPT charging, so you definitely can not do this. Plus what about when you have panels running st say 36V and a 12V battery also connected to the input.
0 Likes 0 ·

Related Resources

Additional resources still need to be added for this topic