Low Voltage Auto disconnect

[bradaz79]

Anyone have experience with a low voltage auto disconnect switch? I’m looking to install one between 2 different battery banks. I haven’t seen much research done on them. Nor many YouTube videos.

If I understand the concept of said switch all I have to do is install the switch between battery bank A and battery bank B on the positive wire. Yes?

What I’m trying to do is separate a lithium battery and a bank of agm batteries. With lithium I can run down to 80% and agm is 50%. So when that agm bank hits 50% I want them to auto turn off so I can protect them.

Thanks Brad

[Bama Rambler]

You could use a voltage sensing relay and power relay to do what you want to do.

Macromatic makes a good line of specialty relays
Here's a Voltage Sensing Relay that would work. Add to that a good heavy duty power contactor like these Trombetta Relays and you could drop the AGM bank out of the circuit.

You'll have to test the setup to make sure you don't get a bounce when you disconnect or reconnect the AGM's from the circuit, so that the sensing relay doesn't short-cycle in and out. That's not likely to happen, but not knowing the relative sizes of your banks, it's best to test it.

[Flybob]

These batteries have fairly different discharge voltage curves, not sure how you would implement the sensor. Might look at marine battery isolaters
I would think charging would be a problem as well.

[bradaz79]

Yea after thinking this out I’m going to use a battery shut off switch

[Photo Lab]

I believe you will find whatever you need on line at waytekwire.com as they have pretty much anything you might need for mobile applications. I've used them for nearly 30 years, and they always have pretty much everything. I remember seeing various types of battery disconnect, charging, and similar stuff, even the 24/12 volt power dividers for those who have a 24 volt bus chassis, and 36/12 for golf carts. Lots of goodies for a technofreak like myself!