cold weather variable heating for lifepo4

[Madcodger]

Deleted my response to another poster

 

[TacomaJoe]

I'm thinking rather than variable voltage, how about PWM? That's how dimmers work. Energy is the same if you apply half the voltage all the time, or all the voltage half the time. Increase pulse width at the temperature drops.

Sensor placement in the box shouldn't be critical. Everything in the insulated box will be the same temperature. An outside sensor would be used to adjust the pulse width to maintain the internal temperature.

 

[JRH]

I'm thinking rather than variable voltage, how about PWM? That's how dimmers work. Energy is the same if you apply half the voltage all the time, or all the voltage half the time. Increase pulse width at the temperature drops.

Sensor placement in the box shouldn't be critical. Everything in the insulated box will be the same temperature. An outside sensor would be used to adjust the pulse width to maintain the internal temperature.

I have two Bluetooth temperature probes in my box .one at the very top and one about an inch off the bottom
.both in free air ,
even with a fan and batteries elevated off the bottom there is about a 5 - 6 degree difference between top and bottom…if the bottom is warm ,the top is always warmer… I use the bottom one for reference …and I shot for about 50F as an ideal minimum this winter.
Depending on temps outside mine bounce from 50 to 55F overnite.

But hey, it’s like hot wings , everyone has to find how much heat they are happy with..

J.

 

[yoopNreb]

https://www.amazon.com/Adjustable-Controller-Automatic-Temperature-Universal/dp/B09L1HJSG3

Is this sort of what your looking for? Might give you some ideas

 

[Visionquest]

https://www.amazon.com/Adjustable-Controller-Automatic-Temperature-Universal/dp/B09L1HJSG3

Is this sort of what your looking for? Might give you some ideas

Interesting find! Concept could be used for sure.

 

[kommando]

Is this sort of what your looking for?

That is to control a cooling fan not drive a heating load, so lower load and wrong direction of temp control. But shows there must be a solution around but why bother when thermostats are readily available, so instead of trying to match a curve to a load to keep a set min temp you vary the time on instead.

KISS keep it simple stupid

 

[Visionquest]

That is to control a cooling fan not drive a heating load, so lower load and wrong direction of temp control. But shows there must be a solution around but why bother when thermostats are readily available, so instead of trying to match a curve to a load to keep a set min temp you vary the time on instead.

KISS keep it simple stupid

Yep, that particular controller is all wrong for the battery application. A PWM approach to controlling heating pads would definitely work but the control circuit likely not worth inventing. So....I'm convinced to keep it simple and ordered my heat pads and temp controller. But doing something more complex appeals to me so I may keep playing around with the idea. The motivation (for me) would be to only apply as much heat as needed at any given point in time with the thought that always using maximum provided heat has some unintended consequence on cell life. Time to jump into my build and get my hands dirty....best way to learn.