charging lead starter battery on/in a lithium system solar

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treecircles asked Apr 11, '21

charging lead starter battery on/in a lithium system solar

hi this is my first post

im spelling is not the best but please bear with me .

so i have put together a diagram of the system

i was using a cyrix-ct relay to top up the van(starter) battery from the house bank which in turn was being charged from the mppt ,this was a great easy system.

so now iv moved to lithium battery bank (house) with ve bms setup im not shore where to best place to link the lead starter battery too ?

i take any advice offed thank you

WOULD LIKE TO NOTE

CHANGED TO PIC. AS SCHOOL BOY ERASERS MADE ON FIRST DRAWING THANKS FOR BRING TO MY NOTENESS

Lithium Battery

wiring-van-1.jpg (196.6 KiB)

wiring-van.jpeg (110.4 KiB)

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Answer 1 · 2021-04-11T13:29:31Z

dazey77 answered · Apr 11, 2021 at 01:29 PM

I don't get many things.

Your fusing the negative lines rather than the positive and have a system where the negative is grounded to the chassis. If you imagine a short to ground/chasis the fault line will go from the positive in fault, through the chassis and negative busbar and return to the batteries via the large fuses which will blow (rather than the smaller circuit fuses). Fusing +ve would be normal.

I don't understand why you have an orion DC-DC and a cyrix. If you have an orion you dont need the cyrix normally.

The alternator is surely already attached to the starter battery, Orion connects to the same place.

Smart shunt is not in the right place as its only monitoring the DC loads, not the charge coming into the batteries (so as far as it knows, the batteries will only ever discharge, not charge). There needs to be no route to the battery -ve other than via the shunt.

MPPT is also going to see the battery disconnect whenever the Cyrix is open circuit, normally it would be the other side.

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Answer 2 · 2021-04-11T13:45:01Z

treecircles answered · Apr 11, 2021 at 01:45 PM

yes thank you , you right fuses on the positive that was an over site when drawing lol the shunt to yes right again lol the reason for the cyrix is to be 100% shore that all charging stops once Li batts are charged to set soc or the temp is to low

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