RLT
10 kW
Finally posting the results of my tests on two of the Battery Space hardcase 20AH cells:
http://www.batteryspace.com/lifepo4-prismatic-module-3-2v-20-ah-10c-rate-64-wh-6-0---un38-3-passed-dgr.aspx
BSP1 Arrived with 3.316V on it, BSP2 arrived with 3.314V.
The following graphs are after about 10-12 cycles each of the batteries previously, but due to various problems with my CBAII, and a few errors of my own, I figured it would be a waste of time to post them. I finally worked out some of the problems with CBA, with heavier wires, better connectors, Arctic Silvering the FET to the heatsink, and more cooling.... So I think the following tests are pretty accurate. even overcoming the Internal resistance of the CBAII ... With these batteries, every time I checked voltage with a good meter, it was within .02V of what the CBA indicated
I accidentally over-discharged both batteries down to 2.0V a couple of times each, and it doesn't seem to have hurt them in the short term. Mostly once I got the CBA running right, I tried to keep the cutoff voltage at 2.5V.
BSP1 @
5A = 20.939AH
10A = 20.659AH
15A = 19.343AH*
20A = 20.369AH
25A = 19.530AH
* I think what caused this anomaly, the less than 20AH results is that for that test, I had charged it at 20A on my Turnigy 400watt charger, terminating at 3.60V, while all the other tests were either charged or at least topped off with a 'Voltphreaks' 2A single cell charger which charges more gently and terminates at ~3.8V. The same thing goes for the 20AH test on BSP2 below.
BSP2 @
5A = 21.379AH
10A = 21.073AH
15A = 20.860AH
20A = 19.957AH*
25A = 20.731AH
I didn't try going higher than 25Amps... although with the modifications to the CBA I might be able to do a test at 30A if anyone really wants me to.
Here are graphs of the tests:
.
Here are links to the actual CBAII test files if anyone is interested in looking closer:
(Right click, Save As, )
http://www.az123.com/E-S/BSP1.bt2
http://www.az123.com/E-S/BSP2.bt2
You don't need a CBA to read and manipulate the test charts... Just download the software from here:
http://www.westmountainradio.com/kb_view_topic.php?id=OT39.
I calculated the Internal resistance of the batteries several times, and never got consistent results... They ranged from .0028 to .0086 ohms, depending the amperages I was comparing. Maybe it was my calculations, rather than the measurements...
With the CBA software and the chart files you can put your mouse at any points on any curve, and get the voltages at that point in time, and calculate them yourself, if you wish...
Or wait a few days... I have a Turnigy meter coming that measures IR, and hopefully it will be more accurate than my calculations.
GENERALLY, it seems as if still after around 15 full charge and discharge cycles that the AH output is growing a bit, all other factors remaining the same.
Here are a couple of photos so you can get a visual idea of the BSP 20AHs, compared to old pre-terminal Headway 38120LiFe and 18650LiIon
Questions?
Opinions?
Do these seem like decent batteries, considering the $35.00 ea. price point?
http://www.batteryspace.com/lifepo4-prismatic-module-3-2v-20-ah-10c-rate-64-wh-6-0---un38-3-passed-dgr.aspx
BSP1 Arrived with 3.316V on it, BSP2 arrived with 3.314V.
The following graphs are after about 10-12 cycles each of the batteries previously, but due to various problems with my CBAII, and a few errors of my own, I figured it would be a waste of time to post them. I finally worked out some of the problems with CBA, with heavier wires, better connectors, Arctic Silvering the FET to the heatsink, and more cooling.... So I think the following tests are pretty accurate. even overcoming the Internal resistance of the CBAII ... With these batteries, every time I checked voltage with a good meter, it was within .02V of what the CBA indicated
I accidentally over-discharged both batteries down to 2.0V a couple of times each, and it doesn't seem to have hurt them in the short term. Mostly once I got the CBA running right, I tried to keep the cutoff voltage at 2.5V.
BSP1 @
5A = 20.939AH
10A = 20.659AH
15A = 19.343AH*
20A = 20.369AH
25A = 19.530AH
* I think what caused this anomaly, the less than 20AH results is that for that test, I had charged it at 20A on my Turnigy 400watt charger, terminating at 3.60V, while all the other tests were either charged or at least topped off with a 'Voltphreaks' 2A single cell charger which charges more gently and terminates at ~3.8V. The same thing goes for the 20AH test on BSP2 below.
BSP2 @
5A = 21.379AH
10A = 21.073AH
15A = 20.860AH
20A = 19.957AH*
25A = 20.731AH
I didn't try going higher than 25Amps... although with the modifications to the CBA I might be able to do a test at 30A if anyone really wants me to.
Here are graphs of the tests:
.
Here are links to the actual CBAII test files if anyone is interested in looking closer:
(Right click, Save As, )
http://www.az123.com/E-S/BSP1.bt2
http://www.az123.com/E-S/BSP2.bt2
You don't need a CBA to read and manipulate the test charts... Just download the software from here:
http://www.westmountainradio.com/kb_view_topic.php?id=OT39.
I calculated the Internal resistance of the batteries several times, and never got consistent results... They ranged from .0028 to .0086 ohms, depending the amperages I was comparing. Maybe it was my calculations, rather than the measurements...
With the CBA software and the chart files you can put your mouse at any points on any curve, and get the voltages at that point in time, and calculate them yourself, if you wish...
Or wait a few days... I have a Turnigy meter coming that measures IR, and hopefully it will be more accurate than my calculations.
GENERALLY, it seems as if still after around 15 full charge and discharge cycles that the AH output is growing a bit, all other factors remaining the same.
Here are a couple of photos so you can get a visual idea of the BSP 20AHs, compared to old pre-terminal Headway 38120LiFe and 18650LiIon
Questions?
Opinions?
Do these seem like decent batteries, considering the $35.00 ea. price point?