LiFePO4 Battery Warmer Install

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
7,479
Location
Somewhere South of Denver
This is my install of a custom set of battery warmers from Ultra Heat. I had contacted them through email asking about a warming profile for LiFePO4 batteries. They responded with a design to my specifications, including warming pads that fit my batteries exactly. While I initiated the conversation with Ultra Heat through their website, the sale went through Annod Industries, inc. which is a distributor for UHI Worldwide, Inc. I paid $344.73 for the kit from Ultra Heat..

Warming Pad Specifications
Two pads per battery, 11.25" wide x 8.0625" tall, 1 amp per pad according to the label on the pad
Temperature sensor: On at 35° F, off at 45° F (One sensor for both batteries)

Batteries
3.2v 280Ah EVE cells
120 amp 4s BMS from OverKillSolar.

The majority of the wiring was included, but I did have to come up with my own harness to complete the wiring to the power source. For my install, their wiring was excessively long, but I was able to tuck the excess away rather than cut it.

These are the pads that they supplied. The side facing down has adhesive to adhere the pad to the battery. The pads are soft and flexible. Each set of pads are connected with what Ultra Heat calls a Packard 4 Place Power Connector. The matching connector is included.
Battery Warmer Pads Unpackaged.jpg

To connect everything to power, I created my own wiring "harness". I created the harness at home after eyeballing the measurements. I was short on some and too long on most. The red wire that includes the switch and goes to the battery should have been longer, but it worked for today's install.
Battery Warmer Wiring Harness.jpg

This is a warmer installed on the side of the battery. The bottom 1.5" of the warmer still has the adhesive peel still on it so that the warmer doesn't stick to the aluminum angle bracket used to hold the battery in place. If I had done the pad install before installing the batteries, the pad would be stuck to the entire side of the battery. I had to remove the threaded rod from the compression assembly to get the pad installed. That was a pain.
Battery Warmer Pad Installed.jpg


The temperature sensor is placed on top of the battery. It's loose in the picture, but it was tucked under the 2/0 cable and taped down to keep it from moving. The sensor is checking the ambient temperature. It isn't clear how well this is going to work. If the pads radiate heat away from the battery then the sensor is going to pick up on that. I hope that isn't the case and the pads radiate most of the heat into the battery cells. If that isn't the case then I'll create an insulation cap to put over the sensor so it picks up the battery temperature, not the temperature of the air above the battery. I don't think placing the sensor outside the insulation that surrounds the battery would have worked. It would cook the batteries.
Battery Warmer Temperature Sensor.jpg

I added 1.5" rigid foam insulation to the sides of the batteries.
Battery Side Insulation Installed.jpg

The top got 2" rigid foam insulation, which is screwed down into the plywood ends of the compression assembly.
20201107_150110.jpg

The wiring harness I created got tucked into a corner and mounted on the wall. I'm very limited on space in this compartment.
Battery Warmer Wiring Harness Installed.jpg

I turned it on and no smoke came out. The temperature inside the trailer was in the low 60's, so the warming pads weren't active. The temperature sensor has a small millivolt draw, too small for me to detect on my BMV-712 monitor. When the overnight temperatures get below freezing I'll make a trip to the storage lot to see the results. Until the pads draw power, I have no way to tell that it's doing anything. It would be handy if the temperature sensor could communicate via bluetooth to an app, but that may be asking for too much.

Overhead view of the compartment where all my components and batteries reside. The compartment was an empty space under a closet.
Battery Warmer Overhead View.jpg
 

LanduytG

Solar Addict
Joined
Apr 19, 2020
Messages
251
Can't wait to see how they do. I bet they will keep the batts toasty down to well below zero. I will be working on this through the winter. Not worried now because we don't have and winter plans for travel.

Greg
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,541
Looks awesome! Thanks for the pictures and providing all the information about your install...


I am planning a similar type setup, using these parts:

1604881933923.png 1604881968590.png

Mine isn't so custom (as I just purchased off-the-shelf parts along the lines of some others had done on this forum), but hoping it will get the job done, I guess we'll find out...

Maybe you can update the thread on how well it works for you as time goes on...
 

Sipma02

Solar Enthusiast
Joined
May 27, 2020
Messages
138
Wonderful work! I did the same thing this weekend, and it worked a treat. I'll be posting about it in my battery build thread, but the gist of it is the same as yours. Nice work!
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
7,479
Location
Somewhere South of Denver
Today I got the temperature controllers installed for my warming pads. All that is left is to clean up the wiring and get the controllers secured.

I decided (for now) to not use the temperature sensor/controller that came with the kit that Ultra Heat created for me. The first controller they provided worked inconsistently. Testing it at home it worked about 50% of the time. I suspect there was an internal wiring issue, but I didn't open it to verify that. The replacement sensor they sent worked every time but the temperature range seemed like it was 30° F to 44° F, not the labelled 35° F to 45° F. I used the temperature sensor from my Fluke 325 meter to check the temperature at the sensor/controller. The Fluke sensor was taped to the Ultra Heat sensor/controller. It isn't clear how accurate it is to tape the two together, but that's all I could figure out.

The new controller I'm using I got off Amazon for $11 based on recommendations from other forum members. It's the LM YN DC 12V Digital Thermostat Module. It has a programmable range, which I prefer to the preset range. Other benefits are that it shows you the observed temperature and the target temperature on the two displays. Each battery now has its own controller. With the Ultra Heat kit, there was only one controller, so it was warming one of the batteries without knowing what that battery's temperature was. Given that the two batteries sat side-by-side and the temp range was conservative there wasn't much risk. With the new setup, there is zero risk.

1604881968590-png.27058

In the test today, after 40 minutes, the warming pads raised the observed temperature at the top of the battery by 8° F. From ~47 to 53° F. I had to fool the controller by putting the temperature sensor into a gel freezer pack. I could have just raised the target temperature on the controller, but didn't think of that until later.

Each time I checked the current on this circuit, it was no more than 1.68 amps. This was with two warming pads active on a single battery. In my opinion, the results are excellent given the small amount of current that was consumed. The pads must be incredibly efficient.

The temperature reported by the controller was within .75° F of the temperature reported by the BMS's remote temperature sensor. I was pleased to see the two devices report almost the exact temperature. The Victron BMV-712 reported a similar temperature, but it reports only whole numbers. Still, it was close enough to call it accurate. I have both sensors (controller and BMS) taped down together at about the middle of the battery. I used some spare rigid foam to create a hollowed out "cap" over the two sensors so they will be reading the battery temperature without (much) interference from the ambient air. The cap isn't sealed, so this isn't 100% effective.

I checked the backside of the warming pads multiple times during the test. I couldn't feel any heat at all. I used an infrared thermometer and it detected only a 5° F difference between the back of the warming pad and the top of the battery.

The new controller is pretty slick. It's a bit confusing to program at first and comes with no instructions. I found a set of user supplied instructions and cleaned them up. If you want a copy, let me know. I'm going to buy another controller and use it for running a fan to keep the component compartment cool in the summer.
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,541
Today I got the temperature controllers installed for my warming pads. All that is left is to clean up the wiring and get the controllers secured.

I decided (for now) to not use the temperature sensor/controller that came with the kit that Ultra Heat created for me. The first controller they provided worked inconsistently. Testing it at home it worked about 50% of the time. I suspect there was an internal wiring issue, but I didn't open it to verify that. The replacement sensor they sent worked every time but the temperature range seemed like it was 30° F to 44° F, not the labelled 35° F to 45° F. I used the temperature sensor from my Fluke 325 meter to check the temperature at the sensor/controller. The Fluke sensor was taped to the Ultra Heat sensor/controller. It isn't clear how accurate it is to tape the two together, but that's all I could figure out.

The new controller I'm using I got off Amazon for $11 based on recommendations from other forum members. It's the LM YN DC 12V Digital Thermostat Module. It has a programmable range, which I prefer to the preset range. Other benefits are that it shows you the observed temperature and the target temperature on the two displays. Each battery now has its own controller. With the Ultra Heat kit, there was only one controller, so it was warming one of the batteries without knowing what that battery's temperature was. Given that the two batteries sat side-by-side and the temp range was conservative there wasn't much risk. With the new setup, there is zero risk.

In the test today, after 40 minutes, the warming pads raised the observed temperature at the top of the battery by 8° F. From ~47 to 53° F. I had to fool the controller by putting the temperature sensor into a gel freezer pack. I could have just raised the target temperature on the controller, but didn't think of that until later.

Each time I checked the current on this circuit, it was no more than 1.68 amps. This was with two warming pads active on a single battery. In my opinion, the results are excellent given the small amount of current that was consumed. The pads must be incredibly efficient.

The temperature reported by the controller was within .75° F of the temperature reported by the BMS's remote temperature sensor. I was pleased to see the two devices report almost the exact temperature. The Victron BMV-712 reported a similar temperature, but it reports only whole numbers. Still, it was close enough to call it accurate. I have both sensors (controller and BMS) taped down together at about the middle of the battery. I used some spare rigid foam to create a hollowed out "cap" over the two sensors so they will be reading the battery temperature without (much) interference from the ambient air. The cap isn't sealed, so this isn't 100% effective.

I checked the backside of the warming pads multiple times during the test. I couldn't feel any heat at all. I used an infrared thermometer and it detected only a 5° F difference between the back of the warming pad and the top of the battery.

The new controller is pretty slick. It's a bit confusing to program at first and comes with no instructions. I found a set of user supplied instructions and cleaned them up. If you want a copy, let me know. I'm going to buy another controller and use it for running a fan to keep the component compartment cool in the summer.


That's great news, it gives me some extra confidence to know you confirmed these seem to work well (since I purchased the same ones, and haven't had a chance to set mine up to test yet)...

I would love to see a copy of your cleaned up instructions if you didn't mind sharing, I do appreciate your review and followup :)
 

solarsimon

Solar Enthusiast
Joined
Oct 9, 2020
Messages
82
Each time I checked the current on this circuit, it was no more than 1.68 amps. This was with two warming pads active on a single battery. In my opinion, the results are excellent given the small amount of current that was consumed. The pads must be incredibly efficient.
Great write up thanks. You mention efficiency of the pads. That's a bit of a misnomer - Any resistive heater is 100% efficient. The only thing controlling the 'efficiency' is the heat loss, which is determined by the insulation. I wouldn't want people to feel these pads offered vast benefits over a homebrew solution.
 

Sipma02

Solar Enthusiast
Joined
May 27, 2020
Messages
138
Nice work! I like that you can see the target temp and the actual temp. Might have to get that unit to replace mine. I also really like that it is in Fahrenheit :)
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
7,479
Location
Somewhere South of Denver
The Android app for my BMS only reports in ° C. That sucks, but I now have the conversion formula memorized.

The one gotcha for the temperature controller is that the mounting holes are really small. I didn't have anything small enough at the time. I picked up some #4 screws at Ace Hardware to try out. I thought about using VHB tape, but didn't have any handy.
 

zgtd01

New Member
Joined
Dec 16, 2020
Messages
4
Looks awesome! Thanks for the pictures and providing all the information about your install...


I am planning a similar type setup, using these parts:

View attachment 27057 View attachment 27058

Mine isn't so custom (as I just purchased off-the-shelf parts along the lines of some others had done on this forum), but hoping it will get the job done, I guess we'll find out...

Maybe you can update the thread on how well it works for you as time goes on...
Did you get it installed? If so how's it working? Did you install under the batteries?
Thanks, Gordy
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,541
Did you get it installed? If so how's it working? Did you install under the batteries?
Thanks, Gordy

Not quite to that point yet. I got my last 8x 280ah cells from AliExpress finally, have my aluminum plates almost ready to go, just have to drill out the holes in the end plates. Bottom plate will be supported by the threaded rods on the bottom side. Might put some angle brackets under the 4 corners of the bottom plate if it needs extra support due to the weight.

I have the heat pads, and thermostats ready to go (will stick heat pad under the bottom plate in center). Should all work. I had been pondering if I thought the 1/4" thick 6061 aluminum would deflect at all once I tighten the end caps down (end caps to have 8 bolts total, 2 per side), and thinking about the possibility of putting a layer of 3/4" thick plywood layered over the outside of the end caps just to make sure it's totally overkill hehe...

I still have some time on this project so I've been doing other things in the meantime, I might get to it either end of this week, or else will have to wait until after the holidays as I need to do a 4-head HVAC install coming up (depending on how long that takes).
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,541
Sure no prob at all :geek:

Here are the heat pads I ordered:

Here are the thermostats to go with each heat pad:
 

zgtd01

New Member
Joined
Dec 16, 2020
Messages
4
Sure no prob at all :geek:

Here are the heat pads I ordered:

Here are the thermostats to go with each heat pad:
Thanks again for the fast reply. Are you concerned about to much heat to fast? I think I would add a probe by the heater and make sure it doesn't heat to fast. If the batteries are cold and the temp probe is on top it may get to hot before shut off. I am using two lion energy 1300 and I may need less heat?? Looking for maybe a 20 watt and I would love a 90 degree shutoff embedded. I love that controller you have and I have already ordered one. Again, thanks, Gordy
 

Freep

Solar Addict
Joined
May 11, 2020
Messages
408
Location
USA
Nice job, Jim.

I think you should seriously consider replacing your screws with posts next time you take your batteries out. Using posts should be a top recommendation for creating new packs. I had a bit of an issue with the threads on one of my cells recently and I'm completely sold on posts.
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,541
Thanks again for the fast reply. Are you concerned about to much heat to fast? I think I would add a probe by the heater and make sure it doesn't heat to fast. If the batteries are cold and the temp probe is on top it may get to hot before shut off. I am using two lion energy 1300 and I may need less heat?? Looking for maybe a 20 watt and I would love a 90 degree shutoff embedded. I love that controller you have and I have already ordered one. Again, thanks, Gordy

Well, that heat pad is only a 150w, so far, I'm not too concerned (if it were the 500w version maybe I might)... Also the consensus from other forum members was that directly applied to a battery case could be a little hot, but mounted on the bottom-side of an aluminum plate (with aluminum having fast heat transfer properties) will dissipate out that heat across the plate quickly. Also the heat pad is only 5" x 5" square, where the aluminum plate is large enough for the entire bank to rest on.

So I am building 3 of these. The 12v (8x cells) bank has a bottom-plate of approximately 11" x 16" and my 2 other 48v (16x cells each) banks will have bottom-plate of approximately 23" x 16""

All three will use the same size 5" x 5" heat pad. I will likely do some testing and monitoring with it in the beginning... Hopefully I will even get it all together before Spring, otherwise will have to wait til next Winter to see it in action.

I will for sure test the bottom plate temp and see what it has the ability to push up to for temp without any batteries sitting on it first.
 
Last edited:

zgtd01

New Member
Joined
Dec 16, 2020
Messages
4
This is my install of a custom set of battery warmers from Ultra Heat. I had contacted them through email asking about a warming profile for LiFePO4 batteries. They responded with a design to my specifications, including warming pads that fit my batteries exactly. While I initiated the conversation with Ultra Heat through their website, the sale went through Annod Industries, inc. which is a distributor for UHI Worldwide, Inc. I paid $344.73 for the kit from Ultra Heat..

Warming Pad Specifications
Two pads per battery, 11.25" wide x 8.0625" tall, 1 amp per pad according to the label on the pad
Temperature sensor: On at 35° F, off at 45° F (One sensor for both batteries)

Batteries
3.2v 280Ah EVE cells
120 amp 4s BMS from OverKillSolar.

The majority of the wiring was included, but I did have to come up with my own harness to complete the wiring to the power source. For my install, their wiring was excessively long, but I was able to tuck the excess away rather than cut it.

These are the pads that they supplied. The side facing down has adhesive to adhere the pad to the battery. The pads are soft and flexible. Each set of pads are connected with what Ultra Heat calls a Packard 4 Place Power Connector. The matching connector is included.
View attachment 27042

To connect everything to power, I created my own wiring "harness". I created the harness at home after eyeballing the measurements. I was short on some and too long on most. The red wire that includes the switch and goes to the battery should have been longer, but it worked for today's install.
View attachment 27044

This is a warmer installed on the side of the battery. The bottom 1.5" of the warmer still has the adhesive peel still on it so that the warmer doesn't stick to the aluminum angle bracket used to hold the battery in place. If I had done the pad install before installing the batteries, the pad would be stuck to the entire side of the battery. I had to remove the threaded rod from the compression assembly to get the pad installed. That was a pain.
View attachment 27045


The temperature sensor is placed on top of the battery. It's loose in the picture, but it was tucked under the 2/0 cable and taped down to keep it from moving. The sensor is checking the ambient temperature. It isn't clear how well this is going to work. If the pads radiate heat away from the battery then the sensor is going to pick up on that. I hope that isn't the case and the pads radiate most of the heat into the battery cells. If that isn't the case then I'll create an insulation cap to put over the sensor so it picks up the battery temperature, not the temperature of the air above the battery. I don't think placing the sensor outside the insulation that surrounds the battery would have worked. It would cook the batteries.
View attachment 27046

I added 1.5" rigid foam insulation to the sides of the batteries.
View attachment 27047

The top got 2" rigid foam insulation, which is screwed down into the plywood ends of the compression assembly.
View attachment 27043

The wiring harness I created got tucked into a corner and mounted on the wall. I'm very limited on space in this compartment.
View attachment 27048

I turned it on and no smoke came out. The temperature inside the trailer was in the low 60's, so the warming pads weren't active. The temperature sensor has a small millivolt draw, too small for me to detect on my BMV-712 monitor. When the overnight temperatures get below freezing I'll make a trip to the storage lot to see the results. Until the pads draw power, I have no way to tell that it's doing anything. It would be handy if the temperature sensor could communicate via bluetooth to an app, but that may be asking for too much.

Overhead view of the compartment where all my components and batteries reside. The compartment was an empty space under a closet.
View attachment 27050
Could you share any info on purchasing your warmers? Any key person to talk with? Also if you are willing any costs for the warmers.
Thanks, Gordy
 
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