I am currently running tests by placing a sample pack of A123 AHR32113s 4S1P in the refrigerator in a project box to simulate trying to warm these up from cold climate and am having difficulties.
These cells will be placed in a vehicle on a much larger scale that are not easily removable. The temperatures here can drop well below 32F which causes much concern if the car is started under this temperature because cells are not suppose to be charged under 32F.
The alternator sizing to cell pack will allow the alternator to charge these around 2.4-3C. They are rated for 5C max.
Anyways, our project box has 1 layer of Reflectix insulation material. It's aluminum wrapped around bubble wrap.
We have 1 layer of this in a cardboard box. We have the primary + and - wire coming out of the box and ran outside the door.
We let it sit for 12hrs. (someone has the frig set to high too, lol)
Temperature inside the refrigerator is 45-48F
Temperature of the Cells at rest is 42F.
Fully charged about 2 weeks ago.
Voltage showing 13.12vDC
We put a 2.7C load on it. After about 3-4 minutes, voltage had dropped to 11.60v and starting dropping a little faster showing capacity has dropped massively due to colder temperature.
But.. even with a 2.7C load, the temperature of the cells on this load only went up to 44.5F after 3-4 minutes.
I have read of people warming their cells up in a vehicle by putting a load on them for a minute and warm them up.. but not these cells.
These cells take a LOT of amps to get warm and that's not going to work in this application to warm them up.
In our normal testing, it took a 29F increase over ambient (79F to 108F) running a 15.2C test to near death.
But doing 1-7C tests to near death, it warms from 79F less than 10F.
What i am seeing is this-
Our thermal insulation is keeping the cells COLDER than the rest of the refrigerator..
I thought it would keep them warmer?
I can add a heating element.. but that's last resort for right now.
Curious on some sort of thermal insulation method to keep the cells warmer than surrounding ambient temps or is heating element only way?
These cells will be placed in a vehicle on a much larger scale that are not easily removable. The temperatures here can drop well below 32F which causes much concern if the car is started under this temperature because cells are not suppose to be charged under 32F.
The alternator sizing to cell pack will allow the alternator to charge these around 2.4-3C. They are rated for 5C max.
Anyways, our project box has 1 layer of Reflectix insulation material. It's aluminum wrapped around bubble wrap.
We have 1 layer of this in a cardboard box. We have the primary + and - wire coming out of the box and ran outside the door.
We let it sit for 12hrs. (someone has the frig set to high too, lol)
Temperature inside the refrigerator is 45-48F
Temperature of the Cells at rest is 42F.
Fully charged about 2 weeks ago.
Voltage showing 13.12vDC
We put a 2.7C load on it. After about 3-4 minutes, voltage had dropped to 11.60v and starting dropping a little faster showing capacity has dropped massively due to colder temperature.
But.. even with a 2.7C load, the temperature of the cells on this load only went up to 44.5F after 3-4 minutes.
I have read of people warming their cells up in a vehicle by putting a load on them for a minute and warm them up.. but not these cells.
These cells take a LOT of amps to get warm and that's not going to work in this application to warm them up.
In our normal testing, it took a 29F increase over ambient (79F to 108F) running a 15.2C test to near death.
But doing 1-7C tests to near death, it warms from 79F less than 10F.
What i am seeing is this-
Our thermal insulation is keeping the cells COLDER than the rest of the refrigerator..
I thought it would keep them warmer?
I can add a heating element.. but that's last resort for right now.
Curious on some sort of thermal insulation method to keep the cells warmer than surrounding ambient temps or is heating element only way?