Delta-V
Solar Enthusiast
- Joined
- Sep 20, 2019
- Messages
- 97
Well, I've recently been tinkering with the Miady 12V@8Ah (Amazon) version.
I had 2 objectives: First, replace a 12V@8Ah sealed lead-acid starter battery for my Champion 3100W inverter generator. This battery keeps dying if it sits too long (several months). Second, I have a bunch of hunting field cameras where I've been using those sealed lead-acid 12V@8Ah universal batteries (UB1280), like what you put in a UPS, as external batteries. They too aren't lasting as long as expected. Especially, since the cameras are only taking motion detected pictures.
So far, I'm happy with it. I'm having a better experience than Will did in his YouTube video. I've done 3 crude capacity tests, it just exceeds expected capacity, about 104Wh (rated 102.4Wh). I used a basic test setup, a Watts-up meter with a 750W Modified sine wave inverter, pushing an old-school 60W incandescent light bulb, Averaging ~77 Watts (or ~6 Amps), about .75C rate, with inverter inefficiencies. It probably would have done better if I'd gone with a .2C rate (1.6A or 20 Watts). The inverter would shut-off at about 10.7V
The battery arrived at 12.2V. I fully charged it, but it fell way short of expected capacity on my 1st test, around 66% or so. But, when I charged it the 2nd, 3rd, and 4th times, it did meet expected capacity. Perhaps Will had the same experience, only basing his capacity test on the 1st charging of 2 different batteries.
I took mine apart to see what's inside. It came apart much easier than Will's approach (no hammer or tin-snips needed, ha ha). I just used a pocket knife blade to pop the glue off around the lid seam. Came off intact no problem.
It's filled with 16 18730 LiFePO4 cells, GZNF18730HP-2000mAh 3.2V, 6.4Wh, purple in color, 4S4P configuration. Looks to be these
It looks similar to what Will shows in his video, but only half the number of cells.
The listing on Amazon didn't have a datasheet or maximum discharge/ charging rating. So, I tried the battery to start the generator, it wouldn't even turn-over. The BMS would immediately cut power off to the battery. I'd have to disconnect a wire then reconnect it to reset the BMS. So, it won't work as a generator starter battery.
I did a test to see what the maximum Amps would be. Briefly reached 32A for a few seconds or so, but the BMS would keep cutting-out. I was able to maintain a continuous 28A for a good 15 minutes or so. Then I checked the battery and it was very very hot! I quickly took the cell pack out of the case and put a desk fan on it to cool it down. After doing some Googling, looks like the maximum discharge rate was 3C (or 24A). Ooops! I wish they mentioned that on the Amazon listing. The 16Ah datasheet someone posted kind of coincides with this. Although, it has 42A for max discharge, which is more like 2.6C (instead of 3C as noted in the 18730 cell spec page) . So, the 8Ah version is probably similar at 8Ah x 2.6C = 20.8A (or 266 Watts) for max discharge. Probably based on BMS limitations.
The BMS does cut-off at about 15V (3.75V per cell) over-charge, and about 9V (2.25V per cell) over-discharge.
Overall, I'm happy with the battery so far. I'll do some more tests. I'm already dropping $20+ buying new sealed lead-acid batteries. Might be a good option spend an extra $10 ($30 total) to get a battery that'll last longer for field cameras.
I did also buy some Headway 38120HP LiFePo4 Cells. 4 of them work great as a starter battery for the generator. I just gotta find a decent BMS for it now.
I had 2 objectives: First, replace a 12V@8Ah sealed lead-acid starter battery for my Champion 3100W inverter generator. This battery keeps dying if it sits too long (several months). Second, I have a bunch of hunting field cameras where I've been using those sealed lead-acid 12V@8Ah universal batteries (UB1280), like what you put in a UPS, as external batteries. They too aren't lasting as long as expected. Especially, since the cameras are only taking motion detected pictures.
So far, I'm happy with it. I'm having a better experience than Will did in his YouTube video. I've done 3 crude capacity tests, it just exceeds expected capacity, about 104Wh (rated 102.4Wh). I used a basic test setup, a Watts-up meter with a 750W Modified sine wave inverter, pushing an old-school 60W incandescent light bulb, Averaging ~77 Watts (or ~6 Amps), about .75C rate, with inverter inefficiencies. It probably would have done better if I'd gone with a .2C rate (1.6A or 20 Watts). The inverter would shut-off at about 10.7V
The battery arrived at 12.2V. I fully charged it, but it fell way short of expected capacity on my 1st test, around 66% or so. But, when I charged it the 2nd, 3rd, and 4th times, it did meet expected capacity. Perhaps Will had the same experience, only basing his capacity test on the 1st charging of 2 different batteries.
I took mine apart to see what's inside. It came apart much easier than Will's approach (no hammer or tin-snips needed, ha ha). I just used a pocket knife blade to pop the glue off around the lid seam. Came off intact no problem.
It's filled with 16 18730 LiFePO4 cells, GZNF18730HP-2000mAh 3.2V, 6.4Wh, purple in color, 4S4P configuration. Looks to be these
It looks similar to what Will shows in his video, but only half the number of cells.
The listing on Amazon didn't have a datasheet or maximum discharge/ charging rating. So, I tried the battery to start the generator, it wouldn't even turn-over. The BMS would immediately cut power off to the battery. I'd have to disconnect a wire then reconnect it to reset the BMS. So, it won't work as a generator starter battery.
I did a test to see what the maximum Amps would be. Briefly reached 32A for a few seconds or so, but the BMS would keep cutting-out. I was able to maintain a continuous 28A for a good 15 minutes or so. Then I checked the battery and it was very very hot! I quickly took the cell pack out of the case and put a desk fan on it to cool it down. After doing some Googling, looks like the maximum discharge rate was 3C (or 24A). Ooops! I wish they mentioned that on the Amazon listing. The 16Ah datasheet someone posted kind of coincides with this. Although, it has 42A for max discharge, which is more like 2.6C (instead of 3C as noted in the 18730 cell spec page) . So, the 8Ah version is probably similar at 8Ah x 2.6C = 20.8A (or 266 Watts) for max discharge. Probably based on BMS limitations.
The BMS does cut-off at about 15V (3.75V per cell) over-charge, and about 9V (2.25V per cell) over-discharge.
Overall, I'm happy with the battery so far. I'll do some more tests. I'm already dropping $20+ buying new sealed lead-acid batteries. Might be a good option spend an extra $10 ($30 total) to get a battery that'll last longer for field cameras.
I did also buy some Headway 38120HP LiFePo4 Cells. 4 of them work great as a starter battery for the generator. I just gotta find a decent BMS for it now.
