Bidirectional low voltage disconnect switch - source

LandCruiserPhil

Expedition Leader
Hi All , Looking for a battery bidirectional LV disconnect switch. Not sure if its the correct term but Im looking for a switch that will separate due to a LV condition but when either side see correct voltage the switch connects.
 

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Herbie

Rendezvous Conspirator
This system from T-Max works as you describe.

It is not very fancy, in that you cannot tweak the set-points, etc. However, the default behavior is good. When there is no "input" voltage to either battery, the relay is open. When the vehicle is running, the relay is closed (starter side.) When my solar or shore-power charger is operating, the relay is closed (house battery side). When the relay would normally be open (no "charge" voltage on either side), I can manually close the relay with the push of a button.

The included relay was so-so, only lasted about 3 years, but I replaced it with a Cole-Hersee continuous duty 200A solenoid and it has worked great for the last 8-ish years.

EDIT: I should mention that I didn't use the battery wire included with my kit either (too small). At this point I'm only using the controller.
 
Last edited:

john61ct

Adventurer
I inferred they just meant they want the contactor to open based on voltage dropping to the setpoint, aka LVC.

Which indeed VSR / ACR / combiners do work that way, literally dozens fit the vague request in the OP.

Some also include a HVC, or auto-adjust for 12V vs 24V systems.

The continuous amps rate is the usual critical factor, those robust enough for manual self-jumping override cost more.

Very few are voltage setpoint adjustable, most use around 13.3V as the isolation point, which is around full resting for LFP.

Most are dual sense, but some one way only. Some actively limit current, or drop voltage a bit.
 

LandCruiserPhil

Expedition Leader
This system from T-Max works as you describe.

It is not very fancy, in that you cannot tweak the set-points, etc. However, the default behavior is good. When there is no "input" voltage to either battery, the relay is open. When the vehicle is running, the relay is closed (starter side.) When my solar or shore-power charger is operating, the relay is closed (house battery side). When the relay would normally be open (no "charge" voltage on either side), I can manually close the relay with the push of a button.

The included relay was so-so, only lasted about 3 years, but I replaced it with a Cole-Hersee continuous duty 200A solenoid and it has worked great for the last 8-ish years.

EDIT: I should mention that I didn't use the battery wire included with my kit either (too small). At this point I'm only using the controller.
Exactly what Im looking for at a great price point. Thanks
 
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