Battery: PUPVWMHB 12v 100Ah mini
https://www.amazon.com/dp/B0CYZQ7Y45/ (not an affiliate link)
tl;dr Desired test results - Worst case cold discharge performance specs in terms of highest amperage I can draw with cold soaked battery at different SOCs.
How should I test:
My timeframe for testing is limited, so I want to be able to test quickly, but how should I do it? Tomorrow morning it will be 5f at it's coldest which is an unseasonably cold temperature for late November so it's an opportunity but 11am it will already be 10f and 2pm it will be 15f.
What I don't know is how long does it take for a battery to cold soak so the next result is valid? I was thinking to test at 100% SOC, 80% SOC, etc. but that doesn't seem like I can do that realistically. Should I just do one pass/fail test at 40% SOC to get my bearings on the current needed to get to a target voltage drop of 10.8v?
I have a variable load that I will be using. I can quickly dial in to any amperage I need, say 30 amps, 50 amps, 100 amps, it could even trip the BMS on overcurrent but that's not my goal.
I already know from testing LiFePO4 batteries that they heat up on their own under a heavy load of even .5c or so and I'm trying to avoid that with this test because I want to know from a cold soaked battery at a specific SOC what I can realistically pull from the battery without dropping below 10.8v(inverter starts to scream at this voltage) or whatever the JBD BMS cutoff voltage is.
Details:
I bought this battery for $149 off of Amazon and one of my uses for it will be to go camping with this battery in the middle of February, during the winter in northern Minnesota. February 2024, it got down to 5f(-15c) during the same camping trip which was cold enough for a cold exposed smartphone to shut down at 62% SOC the moment the display was turned on, just long enough to see the SOC.
Most of my usage is going to be very low wattage at night with a heated blanket. Last year I slept with a polar sleeping bag and enough blankets to be warm, but I'll be at least using the heated blanket to get all of those layers warmed up because it was about 5 minutes of 'dancing in the sleeping bag' wiggling around to get warm enough to be comfortable and I'd rather heat it up before getting inside. I'll do some testing to see how much power the blanket uses but it's rated for 5 amps and has multiple settings so I'll do some testing to find the low setting and also have some tricks up my sleeve using a USB-C PD trigger board and a 12v USB-C plug to drop the voltage to 9v or 5v to lower the current even more as needed.
..but I want to be able to pull more wattage for other purposes such as heating water with a 12v kettle, most of these on Amazon are rated 120 watts(10 amps) but some are 250-400 watts. I'm not planning on using an inverter for this trip, but I'm curious if I decide I could use it how much I can draw from the battery. Do you think the battery can do .5C 50 amps at, say, 40% state of charge at 5f(-15c).
Gotion cells - My understanding based on a Youtube teardown review from the Clark's Adventure channel is that PUPVWMHB and Elefast 100Ah batteries use Gotion cells, along with a JBD(Overkill BMS compatible) which means anyone using Gotion cells might also benefit from this information too if they have a cold temperature use case like mine. Gotion cells are rated for 2C max continuous discharge, 3.5C for 30 seconds. The BMS isn't going to let me use the cells that way but it's good information to know.
I know the real answer is to insulate and heat the battery, but at the moment I'm trying to science while it's cold enough to do this because testing is fun.
https://www.amazon.com/dp/B0CYZQ7Y45/ (not an affiliate link)
tl;dr Desired test results - Worst case cold discharge performance specs in terms of highest amperage I can draw with cold soaked battery at different SOCs.
How should I test:
My timeframe for testing is limited, so I want to be able to test quickly, but how should I do it? Tomorrow morning it will be 5f at it's coldest which is an unseasonably cold temperature for late November so it's an opportunity but 11am it will already be 10f and 2pm it will be 15f.
What I don't know is how long does it take for a battery to cold soak so the next result is valid? I was thinking to test at 100% SOC, 80% SOC, etc. but that doesn't seem like I can do that realistically. Should I just do one pass/fail test at 40% SOC to get my bearings on the current needed to get to a target voltage drop of 10.8v?
I have a variable load that I will be using. I can quickly dial in to any amperage I need, say 30 amps, 50 amps, 100 amps, it could even trip the BMS on overcurrent but that's not my goal.
I already know from testing LiFePO4 batteries that they heat up on their own under a heavy load of even .5c or so and I'm trying to avoid that with this test because I want to know from a cold soaked battery at a specific SOC what I can realistically pull from the battery without dropping below 10.8v(inverter starts to scream at this voltage) or whatever the JBD BMS cutoff voltage is.
Details:
I bought this battery for $149 off of Amazon and one of my uses for it will be to go camping with this battery in the middle of February, during the winter in northern Minnesota. February 2024, it got down to 5f(-15c) during the same camping trip which was cold enough for a cold exposed smartphone to shut down at 62% SOC the moment the display was turned on, just long enough to see the SOC.
Most of my usage is going to be very low wattage at night with a heated blanket. Last year I slept with a polar sleeping bag and enough blankets to be warm, but I'll be at least using the heated blanket to get all of those layers warmed up because it was about 5 minutes of 'dancing in the sleeping bag' wiggling around to get warm enough to be comfortable and I'd rather heat it up before getting inside. I'll do some testing to see how much power the blanket uses but it's rated for 5 amps and has multiple settings so I'll do some testing to find the low setting and also have some tricks up my sleeve using a USB-C PD trigger board and a 12v USB-C plug to drop the voltage to 9v or 5v to lower the current even more as needed.
..but I want to be able to pull more wattage for other purposes such as heating water with a 12v kettle, most of these on Amazon are rated 120 watts(10 amps) but some are 250-400 watts. I'm not planning on using an inverter for this trip, but I'm curious if I decide I could use it how much I can draw from the battery. Do you think the battery can do .5C 50 amps at, say, 40% state of charge at 5f(-15c).
Gotion cells - My understanding based on a Youtube teardown review from the Clark's Adventure channel is that PUPVWMHB and Elefast 100Ah batteries use Gotion cells, along with a JBD(Overkill BMS compatible) which means anyone using Gotion cells might also benefit from this information too if they have a cold temperature use case like mine. Gotion cells are rated for 2C max continuous discharge, 3.5C for 30 seconds. The BMS isn't going to let me use the cells that way but it's good information to know.
I know the real answer is to insulate and heat the battery, but at the moment I'm trying to science while it's cold enough to do this because testing is fun.
