Has anyone experience of using the “Contact” port of Plyontech batteries to implement a sort of Low SoC protection system?
The use case would be an off-grid un-manned site where there is the risk the battery reaches a very low SoC and there being potentially a few weeks until someone can resolve a power supply issue.
The solution I imagine would be to turn off the battery at say 10% SoC via a relay on the Cerbo. That would leave enough in the battery for it to sit idle for some time without damage.
Curious if anyone else has implemented a similar solution.
Just curious why you wouldn’t use a low SOC shutoff in the inverter, with suitable restart threshold?
Sure, it would still be supplying device idle loads, but at 2W the Cerbo doesn’t pull much.
Most likely this would be for an application with DC only loads. The loads themselves would be switched off at say 15% SoC via a relay and NodeRed flow.
I’m concerned about very low SoC on the Pylontech and potentially issues reviving the battery at a remote site by untrained individuals.
Did you use one (1) button for all 6 devices? Or six (6) buttons, one for each device. Or two (2), one (1) for the MP’s and one (1) for the Pylontech’s?
I have a made a relay board for it that is powered from the 12v output of each multiplus
Connected to 2 emergency stop buttons (2 locations)
I designed it in a way thats its absolutly always working and fail safe
But for 3 multiplus you need 3 NC contacts
(In case of stop these should break contact)
For 3 batteries you need 3 NO contacts
(In case of stop these should make contact)
However Emergency stop buttons with multiple switch contacts are available
According to this thread the BMS of the Pylontech draw about 2W when it’s on but no loads attached. So depending on the capacity of your battery that could be 1%/day.
The 48V Battery Protect is a beast of a thing. Too big to put in a small electronics enclosure. Can achieve the same with a small solid state or mechanical relay for the loads I’m designing for.
