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Hans avatar image

Smart Battery Protect Wiring

I recently installed a solar power system on my Class A motorhome. It consists of Victron components: 150/60 MPPT solar controller, Cerbo GX, Touch 50 and a 3000w inverter/charger all in 12 volts. I have four Battle Born 100Ah lithium batteries. The controller is wired to charge the batteries directly. My dealer/designer/tech company is adamant that I should install the SBP to protect my expensive lithium batteries. As he put it, “Do you know how many people have “grave-yarded” their lithium batteries? Everyone at least once.”


In reading about the product, I now understand that it doesn’t do REVERSE CURRENT. In my technologically challenged mind and from reviews of users of this product, it is clear that you can’t wire this inline between the batteries and an inverter/charger because of the no reverse current limitation. Additionally, the diagrams in the manual do NOT show an inverter, only batteries and a load with the SBP in between.


So I’m wondering how to wire the SBP in a system with lithium batteries and an inverter/charger or whether it can be used in such a system. I’m wondering if I could wire the SBP “around” a wire that serves as a charging conduit. I use 4/0 welding cable wired off the batteries through a 400A slow burn fuse and then through a Blue Sea Switch to the coach and inverter/charger. My thinking is that I’d put the SBP between the fuse and switch, leaving the existing cable between them in place and simply creating a short route around this connection.

The questions are: 1) would this isolate the SBP from a reverse current condition and 2) would it work? Any takers on answering this idea?

Battery Protect
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3 Answers
nebulight avatar image
nebulight answered ·

Your installer is incorrect here. Your battleborn batteries have an internal BMS which will prevent over discharge. A Battery Protect isn't needed for drop in style lithium batteries with an internal BMS. A battery protect is required between batteries and DC loads to turn off the DC loads with a ve.bus style bms or other external BMS.

Also you should NEVER install a battery protect between a battery and inverter. The battery protect mosfets cant handle the high inrush current and will be damaged. This has been discussed here several times.

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Hans avatar image
Hans answered ·

The SBP is to prevent excessive and destructive discharge of the lithium batteries. I believe that I’ve figured out how to connect it. I need an on-off switch between the fuse and the SBP and a 2-way switch (a 1 or 2 position switch) between the SBP and the coach/loads. I’ll leave the existing wire between the fuse and what will become the 2-way switch. With these two switches, I can direct power from the batteries through the SBP when I’m boondocking and not charging the batteries from shore power and the inverter/charger. When I am hooked up to shore power, I’ll switch the 2-way switch so that charging power does NOT go through the SBP and I’ll turn the on-off switch between the fuse and SBP OFF so that power can’t pass through the SBP.


I do have another question. Does anyone know why the SBP manual says that it “can give off corrosive gas”. I did read a review on Amazon where a guy in 2019 said, “When inspecting my system after installing a SBP, I smelled something burning. I looked over and saw the SBP melting on the wall.” Whoa! I suspect that he may have run charging power in reverse through the SBP, but that’s just a guess.

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tg1 avatar image
tg1 answered ·

Can you provide any more detail on how your dealer wants you to use the SBP to protect your battery bank?

Are we talking as a disconnect to avoid low SOC conditions or a disconnect to cut battery charge current?

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