Battery Disconnect

[Fdnavy]

What’s the best way to wire a battery disconnect to a battleborn battery. I am using the Victron BMV 712 with the shunt. If I put the disconnect between the battery and the shunt I understand the 712 won’t be accurate until it gets a full charge. What’s the best way to wire this in?

[Nwcid]

Not a lot of details to go on.

Typically you should have some sort of protection near the battery. If your total amperage is low enough I am a fan of these style 12v breakers.




If you need circuit protection larger than made in this style you will have to add circuit protection and then you can use a cutoff like this.

[Fdnavy]

I have a 200amp fuse between inverter and the battery on the positive side. I have the victron BMV-712 battery monitor on the on the negative terminal. I’m not sure I understand what you mean about protection. I just want to install a battery disconnect. So The battery doesn’t draw down when the camper sits unused. If I put the disconnect on the negative terminal before the 712 shunt the 712 will lose synchronization of the soc it won’t be accurate until I power back up and go through one full charge cycle. On the other hand. If I put the disconnect off on the positive side I’d have to put several positive leads on the on side of the switch and I am not sure they will all fit. How does everyone else have their battery disconnect wired?

[Persistent]

Shunts are usually installed in the negative side of the battery.
Battery disconnect switches are usually installed on the positive side.

The battery monitor may have a + voltage wire connected to the positive side. Installing the battery disconnect between the battery positive and the monitor + voltage wire would be typical. The monitor would be "off" when battery disconnect is "off".

Installing the battery disconnect on the house side of the monitor + voltage wire would let the monitor continue to work. It would consume power during storage and shorten how long you can store before recharging. Some use only a trace. Others use more.

Recharge before battery voltage drops below 12.4 volts. Recharge takes 14 hours to prepare for continued storage.

Using a bus bar or other device on the house side of the disconnect to connect many cables may be necessary. Such a device may be a copper bar with holes drilled for bolts to connect cables. Large current cables should be in direct contact with the bus bar. Stacking many high current cables together on one bolt will usually work, but not as well.

Many types of bus bars or terminal blocks are available on Amazon.

A 12 volt high current circuit breaker like the one shown above can double as a battery disconnect switch. Bussmann brand is the tried and true brand. They come in all sizes. Replace the 200 amp fuse with a Bussmann 200 amp breaker and connect everything including the inverter to it. Fewer connections in a circuit work more efficiently.

I wish you good luck and happy trails ahead!

[Nwcid]

What I mean by protection is a fuse or circuit breaker right off of the battery on the positive side.

You said you have a fuse so you can either replace it with a 200 amp breaker or a shut off switch rated for at least 200 amps.

If you have several positive connections you can/should add a busbar which can easily be had in 2 styles. Those with a few large terminal posts or 2 large posts and several small posts.

A typical system would be battery + to as short of wire as possible to your protection, either fuse or breaker. From protection to shut off switch. From shut off switch to busbar to distribute the load.