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.
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.
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.
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.
I added 1.5" rigid foam insulation to the sides of the batteries.
The top got 2" rigid foam insulation, which is screwed down into the plywood ends of the compression assembly.
The wiring harness I created got tucked into a corner and mounted on the wall. I'm very limited on space in this compartment.
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.
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.
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.
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.
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.
I added 1.5" rigid foam insulation to the sides of the batteries.
The top got 2" rigid foam insulation, which is screwed down into the plywood ends of the compression assembly.
The wiring harness I created got tucked into a corner and mounted on the wall. I'm very limited on space in this compartment.
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.