I just want to start by saying that if my battery work is not news to you, you may want to read through the wall of text below because theres at least one new topic in here if not more.
The Main Objective:
All of my data (spread sheet and word file), test sheets, graphs, logs, pics, etc are hosted on my Google Drive and can be downloaded HERE.
As most of you know I've been testing LiPos and NiMH AAs and comparing them via a Spreadsheet (LiPos) or a Word File (NiMH AAs) for the last year and a half or so. While I'm not going to go nearly as in depth with the explanations this time around I will lay out the basics of what I'm doing and how I'm doing it since the original thread with all the detailed info in it got deleted. While the data in the spread sheet is not subjective the value of how much the better performing LiPos are worth to you is subjective and only you can decide that. This comparison guide is only meant to give you the raw data on how batteries perform so you can make up your mind for yourself as to what you want to buy. In regards to the "value" factor, I just want to point out that the prices listed in the spreadsheet were the prices at the time I purchased the batteries and like everything else most of them have gone up, especially recently so you'll have to research the current prices to make sure you know the current prices. I'm going to leave the prices I paid on there just as another means of comparison.
On to the equipment...
The equipment I'm using is a combination of the following:
Hyperion eMeterII datalogger
Progressive RC ESR Meter Mark II
DL24 &DL24P electronic load (Only difference between these two units is the DL24P is 180W and the DL24 maxes out at 150W)
SkyRC BD250 Battery Discharger & Analyzer
and for the really high current load testing I built a resistive load tester. The build thread for which you can find HERE if you're interested. If you only want to see the pics you can find those HERE.
A brief overview of the how:
All the stats listed in my spread sheet are averages of multiple tests done and various amp draws, starting with 1C and working up to 100A tests. The packs go through a total of 15 cycles. Three 1C cycles for comparing Stated mAh rating against True mAh rating, three 2C cycles to break in the packs, three 35A cycles, three 70A cycles, and three 100A cycles. All of the data from those cycles are added together and then averaged to derive the final results. Other data is collected too besides just the mAh and voltages like True C Rating and IRs. Now I've even started including mAh rating under load which is also and average from all of the electronic load tests. Just as a side note, I also created two new columns to the spread sheet that gives a percentage of mAh under load compared to not only the stated mAh rating on the pack but also compared to the actual mAh rating. I felt like this was necessary as a LiPo can output 94% of its true mAh rating under load but its true mAh rating could be 1000mAh less than its advertised mAh rating. Occasionally other data may be collected on the test sheets that don't make it to the spreadsheet like pack temps at various amp cycles or any abnormalities with the pack that I might find. I kinda only do the temps now when I notice a pack is overly warm, mainly because I noticed that the good lipos don't typically have temp issues like the crappy batts do
For those wondering about variations in performance from pack to pack or those wondering if my test results are repeatable I will say that I have begun exploring that aspect and have recently purchased 9 more LiPos that are the same LiPos as other packs I've already tested. I've run 3 of those LiPos through the gauntlet and two of those LiPos were the same LiPo so I have 3 sets of results from the 3 Purple Tindling 5200mAh 50C packs. The initial results are showing that those initial packs that I've tested all had similar results to each other. The other two matching Orange Tindling 5200mAh 50C packs produced similar results to each other also. I'm confident that as I test more LiPos thats I've already tested the results will be within acceptable tolerances. If any big discrepancies are found between two identical packs, I will order a third or even a fourth one if I have to in order to try and see what is causing said discrepancies.
This is what the Test Sheets look like and shows the tests and the order in which they are carried out. *NOTE* The Average mAh Under Load does not appear on this older test sheet. It is now on the current test sheets however. The mAh Under Load statistic is something that the data logger has always captured but at first I wasn't putting it on the test sheets. Thats why I've been able to go back through all of the test results and get those numbers to put on the spread sheet.
This is an example of one of the discharge graphs.
For the skeptics:
I freely admit that I'm not an engineer, I am an IT manager for the Department of Defense. I do in fact work in an entire organization that specializes in R&D for the DOD, so while I'm just a lowly IT professional I have in fact had my work reviewed by some of the electrical engineers that work in the same building I do on top of what I know about electronics from the 25+ years I've been in IT. In terms of building a database for the purpose of creating a solid platform to be able to objectively compare LiPos I think any engineer or electronics professional would be hard pressed to dispute my data or the manner in which it is collected. To that end I have not only made the results of the testing available but also the data logs, graphs, test sheets, methodology, and equipment used available in case anyone wants to investigate my data. I'm confident enough in not only what I'm doing but also how I'm doing it to provide full transparency to those interested in what I'm doing.
Thanks,
Greywolf74
The Main Objective:
All of my data (spread sheet and word file), test sheets, graphs, logs, pics, etc are hosted on my Google Drive and can be downloaded HERE.
As most of you know I've been testing LiPos and NiMH AAs and comparing them via a Spreadsheet (LiPos) or a Word File (NiMH AAs) for the last year and a half or so. While I'm not going to go nearly as in depth with the explanations this time around I will lay out the basics of what I'm doing and how I'm doing it since the original thread with all the detailed info in it got deleted. While the data in the spread sheet is not subjective the value of how much the better performing LiPos are worth to you is subjective and only you can decide that. This comparison guide is only meant to give you the raw data on how batteries perform so you can make up your mind for yourself as to what you want to buy. In regards to the "value" factor, I just want to point out that the prices listed in the spreadsheet were the prices at the time I purchased the batteries and like everything else most of them have gone up, especially recently so you'll have to research the current prices to make sure you know the current prices. I'm going to leave the prices I paid on there just as another means of comparison.
On to the equipment...
The equipment I'm using is a combination of the following:
Hyperion eMeterII datalogger
Progressive RC ESR Meter Mark II
DL24 &DL24P electronic load (Only difference between these two units is the DL24P is 180W and the DL24 maxes out at 150W)
SkyRC BD250 Battery Discharger & Analyzer
and for the really high current load testing I built a resistive load tester. The build thread for which you can find HERE if you're interested. If you only want to see the pics you can find those HERE.
A brief overview of the how:
All the stats listed in my spread sheet are averages of multiple tests done and various amp draws, starting with 1C and working up to 100A tests. The packs go through a total of 15 cycles. Three 1C cycles for comparing Stated mAh rating against True mAh rating, three 2C cycles to break in the packs, three 35A cycles, three 70A cycles, and three 100A cycles. All of the data from those cycles are added together and then averaged to derive the final results. Other data is collected too besides just the mAh and voltages like True C Rating and IRs. Now I've even started including mAh rating under load which is also and average from all of the electronic load tests. Just as a side note, I also created two new columns to the spread sheet that gives a percentage of mAh under load compared to not only the stated mAh rating on the pack but also compared to the actual mAh rating. I felt like this was necessary as a LiPo can output 94% of its true mAh rating under load but its true mAh rating could be 1000mAh less than its advertised mAh rating. Occasionally other data may be collected on the test sheets that don't make it to the spreadsheet like pack temps at various amp cycles or any abnormalities with the pack that I might find. I kinda only do the temps now when I notice a pack is overly warm, mainly because I noticed that the good lipos don't typically have temp issues like the crappy batts do
For those wondering about variations in performance from pack to pack or those wondering if my test results are repeatable I will say that I have begun exploring that aspect and have recently purchased 9 more LiPos that are the same LiPos as other packs I've already tested. I've run 3 of those LiPos through the gauntlet and two of those LiPos were the same LiPo so I have 3 sets of results from the 3 Purple Tindling 5200mAh 50C packs. The initial results are showing that those initial packs that I've tested all had similar results to each other. The other two matching Orange Tindling 5200mAh 50C packs produced similar results to each other also. I'm confident that as I test more LiPos thats I've already tested the results will be within acceptable tolerances. If any big discrepancies are found between two identical packs, I will order a third or even a fourth one if I have to in order to try and see what is causing said discrepancies.
This is what the Test Sheets look like and shows the tests and the order in which they are carried out. *NOTE* The Average mAh Under Load does not appear on this older test sheet. It is now on the current test sheets however. The mAh Under Load statistic is something that the data logger has always captured but at first I wasn't putting it on the test sheets. Thats why I've been able to go back through all of the test results and get those numbers to put on the spread sheet.
This is an example of one of the discharge graphs.
For the skeptics:
I freely admit that I'm not an engineer, I am an IT manager for the Department of Defense. I do in fact work in an entire organization that specializes in R&D for the DOD, so while I'm just a lowly IT professional I have in fact had my work reviewed by some of the electrical engineers that work in the same building I do on top of what I know about electronics from the 25+ years I've been in IT. In terms of building a database for the purpose of creating a solid platform to be able to objectively compare LiPos I think any engineer or electronics professional would be hard pressed to dispute my data or the manner in which it is collected. To that end I have not only made the results of the testing available but also the data logs, graphs, test sheets, methodology, and equipment used available in case anyone wants to investigate my data. I'm confident enough in not only what I'm doing but also how I'm doing it to provide full transparency to those interested in what I'm doing.
Thanks,
Greywolf74
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