Victron MPPT 100/20 together with a battery switch

DIY
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Hello Friends

I am drawing and installing a lithium system on the ”service side” on my yacht keeping my old AGM starting system. (We are in winter rest so I cannot test very much yet so I will rely on the communitie’s experience and I have two questions):

I will charge my lithiums using a 50A Victron Orion by generator on starting circuit and a Victron MPPT 100/20 from solar circuit.

Below question relates to MPPT and when without shore or generator power.
Easy way is to let MPPT only charge lithium service batteries.
But, I have got an idea to be able to charge also my starting batteries with MPPT 100/20 by connecting ”BATT +” to a battery switch ”1 + 2 + off”.
Then I can choose where to send my charging current.
”1” to Lithium and ”2” to AGM. (Understand I will need to turn off my DC/DC not to get circular.)
Anyone who tested this? Any worries?

One more question on MPPT and solar cells.
My solar cells are 110W fixed and 125W as a foldable ”suitcase”. All installed in parallell.
Will Victron MPPT automatically identify the increase when I connect the additional 125W plug?
Or do I need to cover the 110W with a blanket and ”release” 235W simultaneously?

Thanking you all for som good suggestions.

Kind regards
Borje

2

Parameters for Lithium ans AGM are totally different, so this won’t work without reprogramming MPPT. I use a 10W lightbulb (no, NOT LED) and a diode to supply a trickle current from Lithium to AGM.

This will only work if both panels have the same working voltage (within ~1v), otherwise only the panale with the higher voltage will leave an impression on MPPT.

But switching over is no problem, for MPPT it’s the same as a cloud moving over…

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