Can any of you folks recommend a good one for cheap? I dunno why my various ebay searches turn up nothing. An alarm would be ok, but a switch would be better. So I don't have to get out of bed in the middle of the night :).

Naio wrote:Can any of you folks recommend a good one for cheap? I dunno why my various ebay searches turn up nothing. An alarm would be ok, but a switch would be better. So I don't have to get out of bed in the middle of the night :).Low voltage gets much much worse during the daytime from people using AC units, kitchen appliances, hair dryers, etc. If it's okay late in the evening, it will be okay overnight, unless it's already REALLY borderline low. An EMS works, but they reset automatically. An EMS of course has a lot of other very useful features like open ground, open neutral, etc.Not aware of a simple plug-in device but there might be. Do a google or ebay search for "voltage sensing relay 120 volts" and see what you find. I don't think they are cheap but have not looked. You may or may not need a 30 amp 120 volt relay as well (assuming you have 30 amp service). Even if this would work, by the time you've bought all the other bits and pieces like electrical box, cable clamps, etc. to mount it all in, an EMS may be cheaper. And you'd need to be electrically proficient to be doing this stuff.If you don't have one, get one of those inexpensive plug-in power line monitors. I installed a permanent LED display on the wall so I can see at a glance what the voltage is doing and can be had for dirt cheap on ebay.

To clarify, I don't have an RV. This is for the rig in my sig. No AC. I pretty much only use electricity at night. My concern right now is my cat's low wattage heating pad. It (and the inverter) is the kind of low wattage continuous draw that can sneak up on a sleeping human!

What do you want this switch to do, interrupt 12 V when power falls too low?

westend wrote:What do you want this switch to do, interrupt 12 V when power falls too low?Must be then. Just totally ignore my above post. :( Is this ever done on the 12V system? And only because of the cat? Is it one of those hairless Sphynx cats?

Low voltage disconnect switch? | Good Sam Community

westend
Explorer
Oct 04, 2015
If your cat is healthy, it shouldn't need a heating source. Buy a piece of 1" foam insulation and use that for the floor of the cat's bed. I have two outdoor cats and they are happy all Winter with no electric devices. They love small moving blankets for bedding.
NinerBikes
Explorer
Oct 04, 2015
Get your cat a wool blanket from a thrift shop for it to sleep on or under. Put wool blanket in a small box for it to sleep in. Or bu a small cat bed for your cat at a pet shop.
joebedford
Nomad II
Oct 04, 2015
A low voltage cutoff isn't going to help you. Once the heating pad goes off, the cat will give you no peace. You need more batteries.

Perhaps a 12v heating pad would be more efficient. Like this:

Trillium heating pad

I think they're only about 10W.
Naio
Explorer II
Oct 03, 2015
Yeah, Mex, that may be a better solution!

I can dig out the literature on my inverter later. I dunno if it has a shutoff or not.

I've made boxes and tents for kitties at my S&B before, but always included a heat source. I could make a very warm one, though.

Last night kitty slept in the bed with me, but I did not get a lot of sleep!
MEXICOWANDERER
Explorer
Oct 03, 2015
Cats LOVE cat sleeping boxes. With a hole. Inside is a nest. Faux fur. Kitty will sleep warmer than mommy. One side of box - a cedar shingle for them to claw. ITCHY a sixteen pound Tiger used to sleep around my side when I was 10. Sounded lile a Harley Knucklehead when he was purring. Malamute never ever wanted to come in even at -20F. Curled up on walkway and let snow drift over him. Thought frozen fish was a popsicle. Amazing things pets. Costly too.
Chris_Bryant
Explorer II
Oct 03, 2015
Here's a cutoff kit, doesn't look to hard to assemble, $15.
Bobbo
Explorer II
Oct 03, 2015
.
westend
Explorer
Oct 03, 2015
If you only want to interrupt power to the inverter, a good quality toggle switch could be wired into the inverter's positive phase wire.

If you want to remove power from the battery to all devices, a battery master disconnect switch would be a better choice. Something like this cheap one.
time2roll
Nomad
Oct 03, 2015
Alarm but not cut off.

http://www.amazon.com/VoltMinder-Digital-Volt-Meter
DrewE
Explorer II
Oct 03, 2015
Since the heating pad is 120V, check to see whether your inverter has a low-voltage shutdown. Most do, with an alarm at a somewhat higher voltage.

Voila. Problem solved, unless I'm missing something. Total cost: $0.00