MPPT 17/15 with Lithium NG Battery

DIY
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1

I’m going round in circles a little with this and wondered if anybody has worked out the same question. I have a small DC load requirement (less than 100 watts). 1 x 360 watt 24v solar panel, 1 x MPPT 75/15 with the DC load connected to the load out terminals, here is the confusing bit, I want to use a single 24 volt 100 amp lithium NG battery, do i have to use a BMS?

The MPPT has load out disconnect on battery voltage settings so battery under voltage should not be a problem (disconnect output load if battery drops to x voltage and reconnect when battery recovers above x voltage). Do I need a BMS to balance the cells for a single battery? I also want to connect to an Ekrana for remote monitoring, if I need a BMS should I use the VE.Bus NG instead of the Small BMS NG?

Everything I have seen in manuals with a BMS connected uses a common DC load (load off the battery with smart battery disconnect) I don’t need the disconnect as the MPPT 75/15 does that using the load out terminals so do I even need a BMS or just a Battery Monitor (voltage and temp) to the MPPT?

Any help appreciated

2

You should read the NG battery manuals.

  1. The NG batteries contain cell voltage and temperature monitoring and cell balancing circuits. They do not contain any shutdown features. They do not contain Bluetooth either. You should have a BMS with NG batteries to provide the Bluetooth and shutdown features.

The VE Bus BMS needs a Victron inverter to operate as the negative connection comes from there, but a work around can be made. I do not know what info it transmits to an Ekrano. Regardless of the BMS, small or VE Bus you would need a SmartShunt to give the battery SOC.

The problem with using the load out terminals is you have to stop charging and discharging on the MPPT. The ATC from the BMS will do this for charging, so I suppose the load output low voltage will work for ATD as you propose.

You may be better off thinking about a drop in lithium battery with internal BMS plus a Smartshunt.