DVCC and battery cell voltage balancing - 16S Sunwoda batteries not achieving balance

DIY
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41

I would like to say so but the data says different.

The middle on in the top 3 is having a problem.
The high cells are in number 5 at the bottom a typical problem when there is poor current share because of ohms law. (And others)

In this case individually connecting all 5 would be more ideal than the 3/2 stack. Or a 3/3 stack.

The max stack of 3 in the spec will be because of a certain amount of current being passed over terminals and also balancing.
This would matter more or less depending on the size of the inverter.
If it is a 5kVa then two take off on both sides ends diagonally wont matter as the max current over the bank can only be a certain amount.

42

Yes, this is the BEST solution, but more expensive.

From where you have this detailed Info? Or do you mean b2 has two times the connector resistances?

@mjim says the busbar cables are ALL equal.

What I can see at the photo is: b1, b2 and b3 are at higher SoC levels as b4 and b5. This means, the CD is low at this moment but the SOC level differs greater. That is caused by differences of the single cells (internal resistance, materials, …) But that is unavoidable.

43

Path length is not equal with the 3/2 set up. The 3 battery set up has a longer path to the centre battery.

Screeshots in the previous replies. The min max have addresses. 02:16 is battery 2 cell 16.

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44

Then @mjim must move the busbar cables as I described to check if the situation will change.

45

AFAIK cables were supplied in the boxes and are documented on https://solar.greenheiss.com/wp-content/uploads/2024/11/MANUAL-BAT-GREENHEISS-GH-LI-5.0-WHITE.pdf. My installer did the wiring according to the manufacturer’s guidance so I’d discard the wiring being weird or not strong enough the issue. According to manual’s Page 16 cables weren’t on the battery’s box but supplied on a separate box instead.

I will ask my installer to review the wiring again just in case.

I let it discharge to 20% and will perform a slow charge and see if anything improves. On Monday my installer will review all the graphs and numbers too. If they find a solution I will document it here.

Inverter is MultiPlus-II 48/8000/110-100 with a SolarEdge 8000H on ac out.

46

This is not the problem the problem is ohms law. And no matter what the manufacturer says or recommended its an inescapable law.

Will be keen to hear the findings and of there is a comment on if what you have is intended behaviour or it needs revising.

47

Me too! :smiling_face_with_sunglasses:

48

Short update: my installer reviewed the case and escalated it to the technical service of the batteries (GreenHeiss). I’ll post again here once they share a theory/decide what to do.

EDIT 03/24: no update from my installer/the batteries provider yet. Will nudge them again.

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49

Hi all - The update here is that there’s no update. My installer is in contact with their provider and the manufacturer (Greenheiss). I’ll most likely exercise my rights as a consumer and based on the batteries providing a way lower storage/capacity than what was agreed on by contract terms, request they remove these and install a different brand unless they provide a solution by April 15th.