Recommendations for Low Battery Disconnect

[trailertraveler]

I have a Samlex 300 watt (500 watt peak) inverter that I use to power a TV and satellite receiver that draw 100 watts based on the labels on the devices. The inverter shutoff is at 10.5 volts which is essentially zero state of charge for the batteries. We mostly watch TV at night, so the solar panels are not in play (during the day they will run the TV/satellite without draining the batteries). I would like to have the inverter shutdown at 50% discharge or a little less in the event that I fall asleep and don't shut the TV/satellite off. I am interested in what others may have done to solve this issue.

Thanks!

[GordonThree]

Happy to help, let us know what you work out.

[trailertraveler]

Thanks GordonThree!

[GordonThree]

trailertraveler wrote:

GordonThree wrote:
I'm hardly an expert...

Despite the ratings on the charger, I'd call for a solenoid anyway - it's $20 of cheap insurance for an expensive solar charger.

What solenoid are you using? Most of the ones I have found even if rated for 40Amps are prewired and do not have very large wires and I need at least #8 for the inverter.

Something like this should work well, and give you room for upgrades

12V 150A CONTINUOUS DUTY SOLENOID

[trailertraveler]

GordonThree wrote:
I'm hardly an expert...

Despite the ratings on the charger, I'd call for a solenoid anyway - it's $20 of cheap insurance for an expensive solar charger.

What solenoid are you using? Most of the ones I have found even if rated for 40Amps are prewired and do not have very large wires and I need at least #8 for the inverter.

[GordonThree]

I'm hardly an expert...

Despite the ratings on the charger, I'd call for a solenoid anyway - it's $20 of cheap insurance for an expensive solar charger.

[trailertraveler]

mike-s wrote:
What solar controller? Many have load outputs with LVD. If your controller has a load output you may be able to use that directly, for just the 300W inverter (~30 A load).

This is what I thought. However, the "experts" on another RV forum claimed that an inverter could not be attached to the load side of the controller despite the fact that the load rating was 720 watts (60 amp) and the peak inverter draw for the 300 watt inverter is 500 watts. They claimed things would go up in smoke. I became skeptical of their self proclaimed expertise when they suggested placing the inverter near the entertainment center and making the long 12v run to the batteries even after I told them that I was set up to make the run to the entertainment center on the 120v side. That is why I thought I would see what the folks here might be doing.

I spoke to one of the electrical engineers at Samlex a few minutes ago and he said that as long as the charger was rated for a load greater than 500 watts, he did not see an issue.

[mike-s]

What solar controller? Many have load outputs with LVD. If your controller has a load output you may be able to use that directly, for just the 300W inverter (~30 A load).

[GordonThree]

trailertraveler wrote:
Thanks for the links!

The solar controller load manager could handle a solenoid if I went that route.

I was hoping that someone would share what they are actually using that has worked for them.

I don't have one myself but have been meaning to add at least an alarm.

My inverter will shut down at whatever voltage I program it for, but the other loads like COLP, lights, fridge, all draw until there's nothing left. All that stuff is on a 100 amp fuse block fed from the main 400 amp fuse that feeds the inverter.

The Blue Sea would be nice, but sheesh it's pricey.

Using your solar controller to drive a solenoid sounds like the best solution on hand, you've already got the monitor/shutdown part- just need to add the switch now.

[trailertraveler]

Thanks for the links!

The solar controller load manager could handle a solenoid if I went that route.

I was hoping that someone would share what they are actually using that has worked for them.

[GordonThree]

The Amazon device is rated for 20 amps, so about 200 watts AC.

This Blue Sea device is overkill, rated for 120 amps or about 1200 watts AC

Automatic Disconnect

The Amazon device could be wired to an inexpensive solenoid which would handle oodles of amperage

[Lwiddis]

Can you loan me $39.95, 2oldman?

[MEXICOWANDERER]

MOSFET transistor finals. Cute. Good find senor 2oldman.

[Lwiddis]

When normal, reasonable use drains your current batteries, add batteries. I watch local TV news whenever possible....that's my big use.

[2oldman]

This?