question

abaco avatar image

Cascading 2 Multiplus with two battery banks

Can I feed the second Multiplus into the AC IN of the first multiplus. I do have got 2 different battery banks with individual solar chargers and 2 multiplus. What configuration is suggested?

Is there a possibility to limit the AC OUT from the second multiplus goiong into AC1 from the first one?
(I do not need to get more max AC power out, just using both battery banks )

Thx for helping!

installationcascading inverters
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Hello,

I just saw your post and it's been a while... I am wondering whether you attempted to do your cascade design and how it worked out for you. I am now contemplating the exact same thing, for the exact same reasons.

Many thanks,

Peter

2 Answers
JohnC avatar image
JohnC answered ·

Also, it's possible to limit AC IN on the downstream Multi, but there's a lower limit. It's an on/off thing too, so control may arise as a serious issue.

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Mark avatar image
Mark answered ·

I think what your proposing may work but its not a typical/recommended arrangement, I expect that it would keep draining the batties connected to the 1st unit to both power the load & charge the 2nd battery bank.

I would probably create 2 individual systems powering independent loads.

Alternatively, if both MultiPlus units are 100% identical you could run them in parallel & have both battery banks in parallel (but this is not great or recommended for different capacity/type/age battery banks, although some people do it).

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Thank you Mark. If nothing else works I will split it up for different loads.

I hoped to find a nice sollution using the older battery bank and the new one in one system.I heared from some possibilities with the venus to get it a kind of power assist mode. I do have got a CCGX on the one side and a Venus on the ohter.
Even thought about using 2 Diode Battery Combiners (for getting the older batteries on one an the newer one, but I don't know the effect of beeing connected still on the negative pole?).

Dear Mark,

just because of curiosity;

Why don´t you recommend to put 2 Mulitplus inverters in Parallel? Is this because @abaco, wrote that he is charging the 2 battery-banks independently of each other? Ofcoarse, we do also not know exactly what the differences of the banks are, because it has not mean mentioned in detail, like bank voltage(s)/ AH/ batt. type etc...

Because in general, in case of having 2 battery strings in parallel (with equal battery-brand/type, although capacity must not be exactly the same me to my knowledge), It should be possible to let the both multiplus inverters run in Parallel, right?

Also (Victrons) MPPT´s should be able to work in parallel, I thought, if that is desired...

Looking forward for some feedback, as this topic seemed to be ´solved´ so fast, with pretty less information.

Ruben

Hi Ruben, running a full parallel system (with multiple identical MultiPlus units connected to a single/common battery bank) is perfectly fine and supported - my only concern in this case was using the 2 totally different battery banks in parallel to create 1 larger battery bank.

It will likely lead to over-use/charging in one battery bank and under-use/charging the other, eventually leading to premature failure - but people have done it (mixed different batteries in parallel) before.