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grsinva asked

US Van Drawing BJE-300D Design Problems

The BJE-330D design was almost perfect for my travel trailer. I purchased two 200Ah LiFePO4 batteries, the Lynx DC Distributor, VE Bus BMS V2, Cerbo GX, Smart MPPT 100/50, Orion-Tr Smart 12/12-30 DC/DC charger, Smart Battery Protect 100, 500A SmartShunt, 2 200W Solar Panels, 8ga cable, MP4 connectors, and assorted fuse holders, fuses, buss bar - that's most of it. I did not purchase the MultiPlus-II Inverter/Charger. I've encourtered two immediate problems:

1) My trailer uses a AC/DC Converter Charger, so it appears I cannot use the Smar Battery Protect for my DC loads - my DC connection to the DC fuse panel is bi-directional. Is there an alternative, or do I just omit/return the Smart Battery Protect?

2) The VE.Bus BMS V2 manual says "...the BMS obtains battery from the VE.Bus. As such, the BMS connot be used without a VE.BUS Inverter/charger or a VE.Bus Inverter." Is there an alternative to using an Inverter/charger? I am not ready to purchase an Inverter, and may in fact never need one.

Thank You - Greg

Multiplus-IIBattery ProtectVE.Bussystem design
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1 Answer
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pwfarnell answered ·

1. Load disconnect

You MUST have a disconnect on your DC loads and non Victron chargers to protect the battery from under or over voltage and low or high temperature as the Victron batteries do not have cut offs in the batteries. If you had separate charge and discharge lines you would need 2 battery protects, one for loads and one for chargers controlled from the ATC and ATD connections. Can you split the charger to a separate connection. The Battery Protects are good as they have low power requirements. As an alternative you can use BOTH a Victron Cyrix-Li-charge PLUS a Cyrix-Li-Load disconnect relays on the common line working from the ATC and ATD signals so both loads and charging are covered. However, the problem here is on under voltage where you really want to disconnect the loads but not the charger as you need to recharge the battery. The same applies on over voltage, you need to keep the loads on to discharge. If you follow this route, the Cyrix-Li-Load goes closest to the battery. You then need to prepare restart methods in either under or over voltage situations. Best option is to split the loads and charger and get a second Battery Protect. See links for Cyrix relays.

https://www.victronenergy.com/battery-isolators-and-combiners/cyrix-battery-combiners

and

https://www.victronenergy.com/upload/documents/Datasheet-Cyrix-Li-ion-120-A-EN.pdf

2. VE Bus BMS

See an earlier post about connecting negative to the VE Bus BMS without an inverter.

https://community.victronenergy.com/questions/206038/vebus-bms-v2-not-powering-up.html

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