Mechanical Low Temp Cut-In for 10A

[icyroads]

I know I could go electronic, but I’d like to try mechanical first, to control a critical heating load (indirectly via a relay is fine).

Are there any mechanical low temp thermostats to turn on at/below 0F, with or without a relay, not a mercury switch? I find them to cut in as low as 20F, but I need to go lower—could the bimetal spring be manipulated to lower the cut-in?

 

[hwse]

Here is a mechanical but I would use an Inkbird. I have 3 of them on my sailboat.

 

[icyroads]

Here is a mechanical but I would use an Inkbird. I have 3 of them on my sailboat.

That one only goes down to 32F (0C).
I’m looking for 0F or below.

 

[hwse]

It turns on a temps down to 32ºF which would be the minimum turn on temp to allow you to charge. If you need to go lower than that, you can use the Inkbird which goes lower. No matter what tstat you use, you will need power to supply energy to a heating pad. You can discharge from an LFP only down to -20C or -4ºF so you cannot use the LFP to warm themselves up at the temps you are talking about. In that case, you might think about a FLA battery just for connecting to the heating pads to warm the LFP up to the point where it can take over.

 

[icyroads]

It turns on a temps down to 32ºF which would be the minimum turn on temp to allow you to charge. If you need to go lower than that, you can use the Inkbird which goes lower. No matter what tstat you use, you will need power to supply energy to a heating pad. You can discharge from an LFP only down to -20C or -4ºF so you cannot use the LFP to warm themselves up at the temps you are talking about. In that case, you might think about a FLA battery just for connecting to the heating pads to warm the LFP up to the point where it can take over.

I’m not looking to charge. I’m keeping them at a useful/efficient temperature for discharge only in temps down to -20F on what could be a cloudy or snowy day/night/week (ie no solar or not enough solar) for unattended (ie I’m not there to brush off snow or to turn switches) LiFePO4 and lead acid batteries, eg on/heat at -4F and off at 0F.
Once the sun is back out and the panels are miraculously clear of snow, then I’ll let the LiFePO4s heat up to 32F before the charger kicks in. TBH, the panels might not ever get clear enough again until I get back to it in a few days, or the batteries might not warm back up to 32F until I get back to attend to them, but I’d like to keep the batteries at the ready for when I get back. I know that I will have to have a low V cut off just in case it takes me too long to get back or it gets too cold.
I’m looking for mechanical low temp thermostats first, or how a bimetal 32F thermostat might be modified to go lower before I go electronic.
I am also considering FLA to supply the power for heating the LiFePO4s.

The LiFePO4s will also have low temp charge protection.