Handlobraesing
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It seems like the 2.5Ah is the yesterday technology, but the only difference is 8%.
2.7Ah AAs worth having over 2.5Ah ones to you?
- Thread starter Handlobraesing
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dulridge
Enlightened
Handlobraesing said:
Just been playing with new charger that can tell me the capacity at 500mA discharge. The best result from any of my Vapextech 2700mAh cells thus far is 2367mAh with the average over 12 cells being 2269mAh. Still 4 more to go.
Don't have any 2500mAh cells to compare with but will compare the 2300 cells I have a dozen of when the charger finishes discharging the current set. What I'm doing is charging them fully then running the refresh cycle on my charger but this does take a while. I'll borrow a few sets of 2500 cells from someone I share an office with next week to compare them.
For me, when I next buy cells they'll probably be Uniross Hybrio ones as Eneloops are not available locally. The Unoross cells are a bit over $5 each though and someone has just cloned my bank card and emptied my accounts so this may be a while in the future.
Handlobraesing
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paulr said:
The 2650mAh Duracell is pretty much the same way.
coppertrail
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The Powerex 2700s I own are great. After the last charge, I had capacities in the range of 2741 - 2791 mAh.
nerdgineer
Flashlight Enthusiast
I much prefer the low discharge nimhs (eneloops, ROV hybrids, et al) at 2000 mah or so. Not having to worry about leakage is more than worth the reduction in capacity, for me.
I think that manufacturers are getting carried away with the "mAH" numbers game. My 2500's made by Sanyo are all crapping out after less than a hundred cycles. Same with Energizers (also made by Sanyo) and others report similar results. Sure they're 2700mAH but probably right off the charger, and only for low discharge rates. Draw 1C from them or let them sit for a few days or run them through 50 or so cycles and they'll show their true colors. Give me my 1600mAH Panasonics any day. They're probably four years old now and they're still lasting longer than the 2500mAH Sanyo's in my flashlights. I hear Eneloops are also pretty good (they're rated 2AH but has lower self discharge rate)
BentHeadTX
Flashlight Enthusiast
I have used Powerex 2500, Energizer 2500 and Sony 2500 all stamped with the "HR" stamp over the past two years. They are all getting recycled as they die in less that a week from self discharge. 
For the last 7 months I have been using Powerex 2700's and they work very well. Eight of the 2700's are in use for my bicycle lighting, various flashlights etc. Have another 8 cells waiting for me to complete an 8 to 2D Mag mod so I test them on occasion. Those 8 cells are always tested in series as a 9.6V pack. Did a 62 day self-discharge test on them a few months ago and they had 82% capacity. Did another 45 day self-discharge test on them last week and they returned 87%. So far, so good! :thumbsup:
Once the self-discharge test was complete, I ran the pack through 3 cycles of 1080mA charge and 540mA discharge (C/5) down to 1.0V per cell. They returned a 103% capacity reading (2781mAH)!!! The analyzer is a Cadex 7400ER and the eight cell pack has about 25 cycles run through them.
Tested the pack at 1,240mA discharge down to 1.0V per cell and it returned 94% or 2538mAH. Tested two cells about 3 months ago at 1,720mA discharge and they returned 92% or 2484mAH. My MillerMods L1P UWAJ helmet light works very well with those cells.
To sum it up, the Powerex 2700's are working very well for me after about 20 to 35 discharges after 7 to 8 months of use. They hold up very well with self-discharge, can handle high current draws, stay in balance well and keep a higher voltage when discharging. Out of 20 2500's I had, 16 have been recycled and replaced with 16 2700's.
When I return to the states in two months, all my 2500's will be gone, my 3 year old 2300's will get recycled and be replaced with Eneloops.
For the last 7 months I have been using Powerex 2700's and they work very well. Eight of the 2700's are in use for my bicycle lighting, various flashlights etc. Have another 8 cells waiting for me to complete an 8 to 2D Mag mod so I test them on occasion. Those 8 cells are always tested in series as a 9.6V pack. Did a 62 day self-discharge test on them a few months ago and they had 82% capacity. Did another 45 day self-discharge test on them last week and they returned 87%. So far, so good! :thumbsup:
Once the self-discharge test was complete, I ran the pack through 3 cycles of 1080mA charge and 540mA discharge (C/5) down to 1.0V per cell. They returned a 103% capacity reading (2781mAH)!!! The analyzer is a Cadex 7400ER and the eight cell pack has about 25 cycles run through them.
Tested the pack at 1,240mA discharge down to 1.0V per cell and it returned 94% or 2538mAH. Tested two cells about 3 months ago at 1,720mA discharge and they returned 92% or 2484mAH. My MillerMods L1P UWAJ helmet light works very well with those cells.
To sum it up, the Powerex 2700's are working very well for me after about 20 to 35 discharges after 7 to 8 months of use. They hold up very well with self-discharge, can handle high current draws, stay in balance well and keep a higher voltage when discharging. Out of 20 2500's I had, 16 have been recycled and replaced with 16 2700's.
When I return to the states in two months, all my 2500's will be gone, my 3 year old 2300's will get recycled and be replaced with Eneloops.
For me, neither is worth having. The new 2100 mah Rayovac AA NiMh hybrid batteries have a very low self-discharge rate - about 20% after six months. Your higher capacity Energizers or Duracells will lose 20% in about 15 days. I have also found higher capacity NiMh batteries to be much less reliabe with some of them failing after only a few charges.
SilverFox
Flashaholic
Hello Frank,
I think you are a little pessimistic with your self discharge figures for normal NiMh cells...
I don't know about the Hybrid cells, but if you compare Sanyo 2700 mAh cells with Eneloop 2000 mAh cells, the break even point (due to self discharge) is around 53 days. If you charge them up and set them on the shelf at room temperature for 53 days, then do a discharge test, they will give you roughly the same capacity.
Tom
I think you are a little pessimistic with your self discharge figures for normal NiMh cells...
I don't know about the Hybrid cells, but if you compare Sanyo 2700 mAh cells with Eneloop 2000 mAh cells, the break even point (due to self discharge) is around 53 days. If you charge them up and set them on the shelf at room temperature for 53 days, then do a discharge test, they will give you roughly the same capacity.
Tom
Hi capacity cells, that I currently use, are Energizer 2500mAh and Ansmann 2700mAh. From Energizers 50% are dead and rest showing symptoms and all Ansmanns are functioning as they should be. I killed the energizers by leaving them charged on room temperature for about a month or two. Ansmanss has so far handeled this kind of down-time quite well. Also my friend killed a few Ansmanns by deep discharging them.
In short, my experience is that high capacity cells die more easily if deep discharged.
In short, my experience is that high capacity cells die more easily if deep discharged.
Ditto. When I was referring to the high self discharge rate of 2500 mah NiMh, I was referring to the worst ones that seem to occur after only moderate usage. If I fully charge 10, and let them sit for a month, a few will have 90% of their capacity, and others will be almost dead. Each one seems to have its own self discharge rate. Of course, they seem to behave much better when they are brand-new. My only experiences are with Rayovacs, Energizers, and Duracells, so I can't address the reliability of other brands. I'm not sure I believe Tom's numbers will hold true for all high-capacity NiMh's.
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