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LiFePO4 Battery Warmer Install

No, I never considered it. I would be interested to see how that is done though.
I've run PID temperature controllers. These can be setup for modulation. ie if you have a solenoid with a duty cycle, you can say turn it on only for xx seconds, then off. Also the PID allows a lot of control. Proportional = How far are you away from your programmed temp, more heat when its far away, less when it's close. Integral = What is the slope of the temperature over time curve. If it's heading up too fast and will overshoot, then slow down. If its going too slow, speed up. Derivative = What is the area under the temperature/time curve. If it's having more time too cold, the speed it up. If you have been hot too long slow it down.

This should work for any heat cycle. You can auto tune them so it comes up and heats the battery just right, not overshooting it. You can also adjust the P, I, D parameters to shut them down, just using it as a temperature controller and using the duty cycle for modulating the heat. A perfect PID tune will ramp up quickly, slowing down as it approaches the programmed temp, not overshoot the temperature, and not vary by any reasonable temp afterwards. It will perfectly maintain the temperature steady state.

These are the current control systems for many industrial controls.

I use AuberIns. Maybe not this one, but close. Power inputs are almost anything you have. Either SSD control or internal relay. Note: This is the manufacturer that uses industrial temp IC's. At 32F, they stop working and just go to an error state (EEEEEE). I'm currently using this as a feature, knowing the PID will not turn on my propane heat when it's below 32F. It will start working again when the temp is 33F.

https://www.auberins.com/index.php?main_page=index&cPath=1

https://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=237

Carl
 
Heating elements should be selected by total wattage AND watt density (watts per square inch of heater surface area). The total wattage must be able to adequatly maintain the desired internal temperature throughout the expected conditions while the watt density must be low enough to avoid contact "hot spots".
 
Heating elements should be selected by total wattage AND watt density (watts per square inch of heater surface area). The total wattage must be able to adequatly maintain the desired internal temperature throughout the expected conditions while the watt density must be low enough to avoid contact "hot spots".

Yep. Too much power and you get too much heat, possibly concentrated in too small of a spot.
 
Mike got me sorted out today, thanks! 2 kits on order!
UltraHeat says the Z-25N60 8 x 11 Proto Type Kit can be bought by contacting their office. You will want to speak with Mike Lewis, (574) 522-6594 ext. 106 or Mike_l@uhiworldwide.com

Mike designs all of the UltraHeat products and should be able to help you with your request.
 
Yep. Too much power and you get too much heat, possibly concentrated in too small of a spot.
I am reading a lot to get all the information I need to prepare the heating box for my batteries. So thanks for sharingyour knowledge.

From what I am reading, the almost perfect watts per inch would be around .6w/inch !

Does it seams right to you ?
 
I am reading a lot to get all the information I need to prepare the heating box for my batteries. So thanks for sharingyour knowledge.

From what I am reading, the almost perfect watts per inch would be around .6w/inch !

Does it seams right to you ?

I've never calculated the watt/inch. Mine is lower than .6 since my pads are rated for 1 amp each
 
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The pads are expensive, no doubt. But low risk too. If they want to sell more, they're going to have to come down on the price.
Seems...?They make quite a few of the battery warming pads out there. Its an engineered product specifically for batteries in the industry..made in USA?
.as opposed to adapting cup-warmers, pipe-warmers, and/or other Chineses silicone " implants". Not saying its NOT impossible...But their RV products are proven tech.? I don't have time to experiment your results are good for me...thanks.
 
I just joined after reading this thread. I have a Class B motorhome with a small battery box under the van. I got a Manufacturer in China to make two 100AH LFP batteries for me. They claim it has a smart BMS to shut down charging below freezing, but... I am worried about driving below 32 with the alternator charging it, when plugged in to shore power below 32, or running the genny or using my portable solar panel below 32.

IMG_2664.1.jpg

I am going to put this around the exterior of the box:

Foam Insulation Neoprene Sheets with Adhesive,Multi-Function Soundproof Large Marine Closed Cell Neoprene Rubber Roll (W:12 Inch T:1/2 Inch L:59 Inch,Black) on Amazon for $26.​


I ordered this heat pad on Ebay:
NEW ULTRAHEAT RV/ CAMPER HOLDING TANK HEATER Z-25N60 13.5V 15W 2.5A 32" x 8.5" for $58. This is made by the same company as the ones HRTKD got.
With the dimensions of my 2 batteries side by side of 12" by 7", this pad will wrap around 3 sides. I am not sure how to wire it with the Packard 4 place power connector.

The same LM YN DC 12V Digital Thermostat for $11 on Amazon as HRTKD used.​


And this toggle switch (which I am not sure if I'll use):

Asw-13-101 2pin 12mm car toggle switch 12v 20a G3zk on Ebay for $1.69.​


I am learning from this thread and hope I have ordered what I need to be safe and yet not draw too much power from the batteries.

Any thoughts?

Steve
 
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..ordered same, 2 sets.....
View attachment 37883

That pricing is insane. You can get these

https://www.amazon.com/GAOHOU-Elect...ds=silicone+heating+pad&qid=1614352374&sr=8-8

for $13 each for the same wattage/unit. If the density is too high you can buy 4 and run a 2p2s for each battery and get the same wattage. Run all 4 in series if you want even lower density if you dont need very much heat. If you bought 8 your still at half the price.

Edit: Somehow I forgot to add the link to the heating pads
 
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I ordered this heat pad on Ebay:
NEW ULTRAHEAT RV/ CAMPER HOLDING TANK HEATER Z-25N60 13.5V 15W 2.5A 32" x 8.5" for $58. This is made by the same company as the ones HRTKD got.
With the dimensions of my 2 batteries side by side of 12" by 7", this pad will wrap around 3 sides. I am not sure how to wire it with the Packard 4 place power connector.

Yes, those pads are made by the same company. Yours are larger so that may account for the higher amp rating. But I'm not sure that they are designed the same. UltraHeat may be making two different lines of heating pads, one for water tanks and one for batteries. The water tank pads may have a heat range that is too high.
 
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