I tested one of Duracell’s new “holds more charge” “long life ion core” etc batteries, UPC 041333661551, on my hobby charger (Turnigy A-6-10 200W). I took voltage readings in order to compare with HKJ’s Test of Eneloop AA HR-3UWXB 2450mAh (Black).
I set the discharge rate to 5A and I periodically checked the battery using my DMM. At 1Ah the voltage was at 1.1v or better. At 2Ah the voltage was at 1.0v or better. I actually did the discharge several times last night, but forgot to test at the appropriate points during the discharge… So this is like the 3rd or 4th 5A discharge for this cell. Somewhere before 2350mAh the voltage starts to fall rapidly, I didn’t keep a very close eye on that.
I need to make some changes and test again. If I’m reading HKJ’s writeup correctly, he gives a 1hr rest after charging before discharging. My rest period was more like 10 minutes. I also did my charge at 2A, HKJ posted that he charges at 1A. Clearly I’m not going to generate identical test conditions, but I can at least tweak those two things and see if it affects my results.
I let the voltage rebound after yesterday’s test, then charged again at… oh… 2A. Crap. Oh well, I’ll do it again. This time (at 5A) the cell held 1.1v up to 1250mAh. It held 1v up to 2030mAh. Somewhere between 2150mAh and 2200mAh the voltage dipped below 0.9v.
I’m charging again at 1A this time. I’ll do my best to time the rest period to 1hr and then do another 5A discharge.
Excuse me for asking, but isn’t a 5A discharge more than the battery is recommended for? It is like trying to drive a Smartcar up to 200 mph. Just not really what it is meant for. I think the batteries were designed for a more casual usage.
Sometimes its fun to safely push the envelope. My 79 Volvo 245 wasn’t designed to run for more than 340 thousand miles or keep up with sport sedans on canyon roads but it did both. On a budget too !
Fair question. Much as I love to push the envelope J) I don’t think that’s what I’m doing here. I’d say Sanyo doesn’t advertise Eneloop XX as being able to handle a 5A discharge… but Sanyo’s datasheet does show a 5A discharge. For Eneloop, Eneloop XX, and Tensai TR-6 HKJ tested them up to 10A, 10A, and 7A respectively. 10A is probably pushing it.
Other people have already done the physical comparisons - Duracell’s new thing looks and feels like an Eneloop XX as far as I can gather. As far as I know, there is nothing similar on the market in terms of capacity and voltage retention under heavy loads when compared to Sanyo’s Eneloop XX. The purpose of my 5A discharges is specifically to generate numbers to compare against HKJ’s data. Comparing 1A or 3A data wouldn’t be as conclusive as the higher currents (where Eneloops shine). My equipment is limited to 5A maximum, so that’s what we’ve got!
In terms of whether it’s wise to do this to the batteries - I don’t know. I think I have seen someone cautioning that using Eneloops at 10A would… change them in a lasting way. I forget the exact words or who said them. Maybe HKJ, Silverfox, or one of the hotwire builders at CPF. Personally, my plans for these cells involve lower current draws - more like 3-4A or so. FWIW the 5A discharge never made my cell hot - only warm.
On to the latest results!
1 amp charge
1 hour rest
5 amp discharge
At least 1.1v was maintained through 1330mAH
At least 1v was maintained through 2090mAh
At least 0.9v was maintained through 2250mAh
Thanks for doing the testing. I’ve been running these durablock 2400 mah rechargeable aa cells in several household items such as remote controls and motion activated led lights. They are doing well so far. I had some crappy older energizers that didn’t even last a week in these devices.
This is what I did last night, but I did not keep good track of my measurements:
1 amp charge
1 hour rest
5 amp discharge
1.1v maintained past 1300mAh
1v ? I got distracted
0.9v I got back just in time to measure this, but forgot exactly what I measured. I noted that it was similar to the previous discharge.
Basically at this stage the results from this individual cell are pretty clear to me. While I’ve only successfully recorded all 3 of the measurements once, I’ve done a handful of 5A discharges and they all seemed consistent enough.
I have discharged another cell. When I get home from work I plan to charge, rest, and discharge it like the one I’ve already done. If that matches the results I’ve already got, I see no reason to continue this brand of testing. I’m open to any constructive suggestions for further tests.
Sorry guys, I got distracted and we don’t have enough time tonight to do the full, proper, routine on the second cell before bedtime. Instead I’m doing a fast charge at 2.5A, then I’ll rest it for an hour (hopefully), then do a 5A discharge. Probably won’t be able to do a charge/discharge cycle tomorrow, we’ll see. I’ll definitely do the proper routine on this cell ASAP.
Edit: well, that didn’t work out. I got distracted some more. I’ll build a datalogger soon or give up
2.5 amp charge current
1 hour rest period
I measured a 1.45v starting voltage before I started the discharge
1.1v through ? - oops
1.0v through 2070mAh
0.9v through ? - oops again
Thanks guys. Tonight I worked a little on getting an Arduino to do what I want. For testing purposes I wrote voltage out to a character LCD and compared it against my inexpensive DMM and inexpensive digital CC/CV buck converter. They are all off by about 0.01v (eg total spread is 0.02v) - that’s about as good as my accuracy was anyway I’m sure. Very happy with that so far.
I’ve got a data logging shield, which includes a realtime clock and an SD card slot. I should be able to use existing libraries to generate timestamped voltage readings easily. Without monitoring and recording the mAh readings from my charger, I’m not entirely certain how to get that data. Should I just assume a constant 5A discharge and extrapolate mAh based on current & time?
Maybe I should focus on using the serial connection to hook my charger up to a PC and log that way. The problem with that is that the voltage readings are seriously far off (0.4v or something) when discharging a AA. I suppose I could do both and combine the data.
I have quite a few EMD brand “2200mAh” Chinese LSD cells which I purchased from hobbypartz.com. I’ve only used them in low-drain applications. Once I get this test done I could take a look at a couple of those. I’m sure they won’t keep up with the Tensai TR-6, much less Eneloops. It will still be interesting to see exactly what they can handle though.
Any updates? I still have a good feeling that these latest duracell aa are made by sanyo. The mah is pretty much the same as the xx. I have 4 of them running strong in my motion activated led light at the back door.
Not much in the way of updates. I’ve had other things to attend to, so I didn’t make any progress on my voltage logger last night. Looking at the menu flow-chart for my charger I don’t think it has a TTL interface, so I no longer have to worry about whether I should log that :~.
