I use a lot of devices in my work vehicle that are typically running when the engine is off. I was doing some reading into ways to maintain battery voltage and I read that there was a device that would start the engine to charge the battery if the voltage dropped below a preset amount. I've tried some Googling and haven't found any such device. Has anyone heard of something like this?
I assume you're looking for something like this?
The key to this is you're looking for a remote starter which happens to provide a low battery protection option. You must have remote start to do what you're asking, and honestly once that's addressed it really isn't a big stretch to add low-voltage protection.
Just my thought, but I have a similar issue on my race car trailer, which has a huge inverter which runs lights, an air conditioner, a microwave, a refigerator (frozen burritos and healthy hydration liquids) and the DVD player.
(These things are essential when racing a vintage car. Say nothing!)
My actual point is, I have a bank of 3 deep-cycle batteries in the trailer, that charge on the tows to-and-fro from an 8-gauge wire from the diesel tractor. They can also charge from a Honda genset if I throw the right switches.
The beauty is, I bought this "battery isolater" thing, so that even when I am too cool and eat too many burritos and watch too many DVDs, it doesn't kill the tractor (actually just a Ford F350) battery and prevent a start on a cold morning.
So, I'm thinking if you can find a place (trunk maybe?) for just one small RV type deep cycle battery (aka RV terms "house battery"), and get one of these battery isolator thingamajiggies, you can do all your "device" stuff all day long with zero risk of having to call AAA or not getting home.
The "device" [house] battery will be recharged by the vehicle alternator. Most of the "thingamawhatsis" also have a bypass switch that allows starting assistance if the "tractor" battery dies from lights left on, etc.
I can't remember what the brand of my battery isolator is, but I can certainly tell you the place to find this kind of information is in an RV forum. These folks deal with exactly this issue all the time.
In the long run I think this a more prudent and cost-effective solution than having some computer decide when to start your vehicle on a whim. The wiring is simpler and the result much more straight forward.
We've been having this technology in our 18 wheelers for years I don't know where you can find it for regular vehicles my 18 wheeler now has it I have a 2016 Freightliner Cascadia.. another place where I saw this technology I was surfing on YouTube and ran across it on an RV, on a dodge pro master chassis.. ironically I have a 2018.pro master and I have been looking for that damn video every sense... because I need it for my pro master and I don't remember what RV company had it .
They make exactly what you are looking for in motor homes also. Check out this video. I would love to know the parts list to figure out a DIY option as well.