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My system has LFP battery with "2 signal BMS".
Signals are connected to MP-II but there is smartsolar MPPT 150/35 also charging the same battery.
When all is working properly MPPT is externally controlled, but what will happen when "external control" fails (MP-II stops controlling) and MPPT still charges my battery when BMS sends the signal to stop charging to MP-II but not to MPPT?
I assume if you have a GX device (cerbo, venusgx, color control)? If not, you can use a ve.direct non-inverting cable to turn off the MPPT: VE.Direct non inverting remote on/off cable - Victron Energy
However if you have a GX device, the ve.direct cable is in use so you can't use this. This may not be the preferred method, but I use a smart battery protect between the battery and the OUTPUT of the MPPT. I wire the allow to charge BMS signal the remote port of the battery protect. So when the BMS doesn't want charge, it will open the battery protect and disconnect the mppt output from battery. This function would be the same as a drop in battery should the BMS disconnect and got confirmation that this won't damage the victron MPPTs.
Thank you for this info.
I have GX device in the system, so this cable cannot be used.
Do you know which model of battery protect should I use for this MPPT 150/35?
As a additional question.
In my system I have EasySolar-II GX. It has MPPT250/70 inside.
Do you know if this problem exists also with this internal MPPT?
Since you have a 48V system, you'll need to use the 100 amp 48v model (the most expensive model). If you have a large battery bank, you could just use a contactor on the output of the MPPT. I don't use contactors as they use a lot of power just to remain closed.
As for the Easy Solar, you wont' be able to do that because there is only one battery hookup as the output of the MPPT is on the same bus as the inverter charger and you can't use a battery protect with an inverter charger (inrush current will destroy the battery protect). However, the 250/70 does have a remote on off switch, but as you can see here, it's wired to to the built in GX card. You might be able to remove that connection and wire it to the BMS, but I wouldn't' recommend that as I'm sure that's not a supported configuration from Victron.
If I cannot control MPPT 250/70 inside ES-II, installing battery protect on external MPPT 150/35 will not fix my problem.
p.s. picture is not visible.
