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janroger avatar image
janroger asked

Relay alternatives to Bluesolar MPPT and BMS

I have a Bluesolar 100/50 MPPT solarcharger that is connected to a 15KW Lithium pack from a Nissan Leaf. The package is in 24v configuration and it is balanced by a 123smart BMS. At the moment I do not have a relay controlled from the charger and are looking for options. The BMS has the ability to activate a relay if voltage on one cell is critical high. Since my MPPT do not have a remote option that could connect with the BMS I need a relay between the charger and the battery.
My question is if I can use a Victron Batteryprotect 12/24V 65 A for this? My solarpanels are 400W total and this is used in my cabin.

MPPT ControllersBMS
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Vance Mitchell answered ·

A battery protect can be set up to operate as required.
The other option is to turn the bluesolar off using the ve.direct port .

VE.Direct non inverting remote on-off cable (ASS030550300). See page 4 of the manual.

The safest option would be to use both, the remote cable to disable charging and the battery protect to avoid excess discharge.

do you have a low voltage cut off to prevent over discharge?

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janroger answered ·

There is 2 relay outputs on the 123smart BMS. One for charger relay and one for discharge relay/load relay. The load relay can connect to the Phoenix 24/3000 inverter that I have since it has remote start/stop. I also have a Raspberry PI running Venus OS and this is connected with the MPPT charger, Phoenix inverter and the BMV 700 monitor. Unfortunately it only works when it is connected to a PC and not through WIFI. I only have 4G wifi router on my cabin because it is up in the mountains of Norway.
I had a look at the cable to connect to the MPPT and it sounds like a good idea to use both. I have current sensors on both load and charge connected to the BMS and through Bluetooth can monitor all power usage and charge.

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Vance Mitchell avatar image Vance Mitchell commented ·

Unfortunately the MPPT only has one ve.direct port so with the Pi connected, you can’t use the remote.

The battery protect might be the easiest option in this case.

There could be a way to connect the charge disconnect from your bms to the pi to allow a software disconnect, but I am unsure of the best way to achieve this.

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janroger avatar image janroger Vance Mitchell commented ·

Thank you for your help. I ordered a Smart Battery Protect and it seems like it would do the job

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