Separate Control for parallel banks

I have a watchman core and expansion board controlling 2 cell mate k9 which will monitor 2 parallel banks of 16 cells each. So I see on the chart view 32 cells. (#1-32).
Can I setup the watchmon core to control one relay on expansion board if one cell #1-16 drops to 3v. And also setup the watchmon core to control a different relay if one cell #17-32 drops to 3v.
Or do I have to have 2 watchmon core?

Thanks for you support.

Hi Magneticpwr,

Thanks for posting! Welcome to our forum :slight_smile:

For now you will need two WMC, as the WMC is in charge of the control logic, but since we are seeing more multi-string or HV systems, so we are working on new hardware to solve this problem.

If you have not built your pack yet, I suggest putting your cells in parallel instead of multi-string:

Thanks, I have 32 300ah cells. I am looking for redundancy, backup, and safety.
I have 2 80amp charge controller to charge the batteries.
Should I use a watchmon core, expansion board, cellmate for each battery bank as 16S1P.

Or am I better off setting up as watchmon core, expansion board, and 2 cellmates. Connect batteries as 16S2P . 2 16 cell banks in Parallel and use the watchmon core to isolate or shutdown an individual bank if there is an issue such as over charging or when a cell hits 3v.


Just to clarify, in reference to the diagrams I posted above, do you mean [2M|16S|1P] or [16S|2P]?

If you want redundancy, yes you will need 2 of everything. Could you elaborate on your needs a little more as to why you need redundancy? Are you completely off grid?

@James, thanks for answering to that.

Indeed it’s a LONG awaited feature to have the WMC control more than one relay depending on certain conditions.

Like @Magneticpwr, a lot of users in Europe are having multiple K9s with multiple 16S battery banks.
In case of any issue/failure, the WMC pulls the trigger on one defined relay, separating all battery banks from the bus bar.

Like @Magneticpwr mentioned in his first post, it would be awesome to have one WMC with its control logic being able to pull relay 1 when failure at cell range 1-16, pull relay 2 when failure at range cell 17-32, and so on.

Most European DIY guys like me run a TE Kilovac EV200 (or an ABB breaker with shunt trip) attached to the WMC relay.

Hope that helps to understand the idea/wish behind it!


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Yes, like Sebastian also said. If there is a 16S bank fault we could isolate that individual bank and not have to shut down the whole system.

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