The AA NiMH Performance Test Thread

[jgbedford]

Wonderful information BG!

I see the Enloops are getting a lot more chatter than the Imedions - why is that?

If I'm reading your results correctly, the Imedions carry higher capacity?

I'm looking for a cost effective way to keep my Canon 580 exII flash going, and want to keep spares in my camera bag - but don't shoot enough requiring me to recycle the batteries through the charger every few weeks.

Confused


JB

 

[Mr Happy]

Wonderful information BG!

I see the Enloops are getting a lot more chatter than the Imedions - why is that?

If I'm reading your results correctly, the Imedions carry higher capacity?

I'm looking for a cost effective way to keep my Canon 580 exII flash going, and want to keep spares in my camera bag - but don't shoot enough requiring me to recycle the batteries through the charger every few weeks.

Confused


JB

Eneloops have an established record of quality, consistency, durability and performance. When you depend on batteries to work reliably then simple capacity is not the only thing that counts. Immedions may be good also, but there is less experience with those and Eneloops have set the standard that others have to follow.

 

[ALW248]

I have been price watching for a while, in the hopes that they would go on sale (kinda getting the feeling that isn't going to happen).

Or for the same price, you might want to wait for the new and better HR-3UTGB.

And after the new one is widely available, maybe the 2 generations old HR-3UTG will go on clearance.

For low power devices like remotes, Eneloop Lite might be better, if it is significantly less expensive than 2AH Eneloop.

 

[Wrend]

Even in something that uses that low of an average current rate, I think the capacity will still get used up faster doing useful work than it would from self discharging.

For the Lites to be worth it (at least in cumulative lifetime capacity potential) they would need to be less than 2/3 the cost of the "1500" cycle ones. Even if that is the case, with twice the capacity the "1500" cycle ones are probably worth it just for the convenience of not having to switch out the cells as often.

Given the capabilities of the "1500" cycle cells, the XX cells are way overpriced, in my opinion. Even if they were the same price, I still think the "1500" cycle cells are the better value. If the "1800" cycle cells are the same price as the "1500," then they'll be the new best deal.

 

[Battery Guy]

Wonderful information BG!

I see the Enloops are getting a lot more chatter than the Imedions - why is that?

If I'm reading your results correctly, the Imedions carry higher capacity?

I'm looking for a cost effective way to keep my Canon 580 exII flash going, and want to keep spares in my camera bag - but don't shoot enough requiring me to recycle the batteries through the charger every few weeks.

Confused


JB

Hi JB

The Imedions have relatively high internal resistance, which results in a lower operating voltage under load. You can see this in the constant current discharge curves. This will result in lower brightness for direct drive flashlights where the bulb or LED brightness is directly dependent upon the voltage of the battery.

For a flash such as your Canon 580 exII, the lower internal resistance of the Eneloop should result in faster flash recharge rates. If the flash pulls a constant power pulse from the battery, you might even get more flashes from the Eneloop because the flash will pull more current from the Imedions to achieve the same power (power = voltage x current). But if you use the flash infrequently and/or don't take flash photos in rapid succession, then the Imedions will probably be just fine.

The Eneloops have a great track record and are known to have a fantastic cycle life, whereas this has not been established for the Imedions, or really any other LSD to my knowledge.

For best ultimate performance in a flash, the Eneloop XX (aka Eneloop Pro) are probably your best choice, but they are expensive.

Hope this helps.

Cheers,
BG

 

[ALW248]

Even in something that uses that low of an average current rate, I think the capacity will still get used up faster doing useful work than it would from self discharging.

For the Lites to be worth it (at least in cumulative lifetime capacity potential) they would need to be less than 2/3 the cost of the "1500" cycle ones. Even if that is the case, with twice the capacity the "1500" cycle ones are probably worth it just for the convenience of not having to switch out the cells as often.

Given the capabilities of the "1500" cycle cells, the XX cells are way overpriced, in my opinion. Even if they were the same price, I still think the "1500" cycle cells are the better value. If the "1800" cycle cells are the same price as the "1500," then they'll be the new best deal.

For my remotes, 2Ah Eneloop would last many years on a single charge. I want to cycle them much more frequently than that.

Even 1Ah Eneloop Lite would last years.

My damaged NiMH, with decreased capacity and increased impedance, last many months in remotes on a single charge.

For applications need more power, I prefer 2.5Ah XX over 2Ah Eneloop.

Although 2Ah is more than enough for a single session, the higher voltage output of XX at 1Ah discharge point is useful.

 

[okc_car_dude]

Hello Everyone! Kind of a newbie here, but definitely an enthusiast! I've been doing research on Li-ion/polymer, LifePO/4, Ni-Zn, Ni-MH, and Ni-Cd technologies. I've studied a lot and jumped around a lot to obtain my information, so forgive me if I can't exactly recall what came from where... =/

That out of the way!...

PowerGenix NiZn: Tested fresh out of the package. Please note that the voltage axis is scaled differently than the other comparisons.

I'm very curious about the Ni-Zn technology, since it appears to be such a great and safe replacement for many Ni-Cd/Ni-MH packs, where Li-ion would not provide a close enough voltage in terms of toy RC's. (I've been making packs for my son's and niece's cars that allow you to remove individual cells to charge them on a standard charger and be able to balance [albeit by manual voltage readings, lol] each cell).

I also bought some extra's for his mom's Sony camera. Since I've personally used it with alkalines and know of it's voltage shut off tech, I figured she'd get much more use and faster recycle times with the Ni-Zn tech... but here are my Concerns...

I recently contacted PowerGenix, since I've seen on different sites, about the periodic "Maintenance Charge." I've seen different stuff about this. Some says monthly, some every other month, some to not let it drop below 1.68v in storage... So I asked them about it and, after an initial charge, if I just so happened to store a cell for months before use, how would effect the performance/life, etc. of the battery... This is what they told me.

Thank you for your inquiry. Optimum cycle life will be achieved by limiting the individual cell voltage at 1.1 Volts (or greater) at end of discharge. Failure to do so will likely result in deep discharge of some batteries, often resulting in polarity reversal, which is detrimental to overall yield of usable cycles. The batteries should also never be stored at a fully discharged state, and should always be charged using only manufacturer approved NiZn chargers.

I am not aware of any "monthly maintenance" requirement, but the NiZn batteries will perform better when they are charged more frequently than not, in other words, they do not like to be fully drained before charging.

I have attached some datasheet information that you might find helpful. If this did not answer your questions please let me know.

Gail
Customer Service

So, knowing this and that someone else on this forum I believe, that tested the cells at rates of something like, 1A, 2A, 5A, 10A, 20A (May be missing one)... They seemed to test fine at 10A, but he killed the cell when trying to test for 20A, even though I originally read they should be safe up to rates of 50C. Lol, sorry... I'm a data nerd. My point is the Ni-Zn curves look less consistant after the 1st 6 or so cycles and I was wondering if they were held to the same 0.8v discharge cutt-off of the Ni-MH? I'm sure this a request among many and I'm so sorry to trouble you, but I'm just wondering if this is what to expect from the Ni-Zn at higher amperage rates, or if they cell's capacity and discharge characteristics were diminished by over-discharge?

Any info [and especially a retest with a fresh cell and a higher voltage cutt-off ] would be greatly appreciated!

Joe

 

[Marc999]

I have 1st and 2nd generation eneloops; all with the exception of 1 or 2 are still reaching their 1900 mAh minimum rating.

I also have 4 Sanyo XX about 1.5 years old. None of these batteries have ever reached the minimum 2400 mAh. Even 2 Break-ins recently didn't achieve the minimum spec. One Break-in round included a 500 ma discharge, 2300 set capacity. The other Break-in round included a 100 ma discharge, 2400 set capacity. The lowered discharge rate didn't seem to make a difference at all in helping to squeeze out most of the juice prior to Break-in. They range from 2250 to 2333. Yes, not far from the minimum spec., yet still.....

So, from my limited experience with the lovely XX's, I'd say the 1st and 2nd generation regular eneloops have faired better.

 

[45/70]

Hi Marc. I'm curious about a couple things. First, how did you "break in" the XX cells? Normally, a break in for 2300mAh cells would involve a 16hr charge at 230mA charge rate, rest 1hr, and then the cell(s) would be discharged at a 0.2C rate (460mA) to 0.90-1.00 Volt (depending on method of discharge, constant current, 1.00 Volt, pulsed current, eg. Maha C9000, 0.90 Volt) to determine cell capacity. The same goes for 2400mAh, only the figures would be 16hr charge at 240mA, 1hr rest, and discharged at 0.2C (480mA) until discharged (again, to 0.90-1.00 Volt/cell). I'm not questioning your results, just what equipment you used for charging/discharging and precisely how you went about the break in process.

Also, any idea how many cycles, full or partial, were on these cells? Were the cells ever potentially deeply discharged, or reverse charged during use? Also, any other factors that may have increased cell degradation, such as high heat, extremely high current use, etc?

I'm not too surprised that the XX cells are not holding up as well as regular eneloops. That's pretty much a given. As with all "high cap" NiMH cells, there have been compromises involved in order to add the additional capacity. I do find it a bit odd though that the XX cells fell short of 2400mAh initially (when new) though. If the XX cells tested 2250-2233mAh after a year and a half, although maybe a bit low, that's about what I might expect.

I'll add here that I have resisted buying any XX cells, so far anyway. Considering the additional cost and expected shorter life cycle, I really have no need for the additional capacity. I thought about maybe just buying four cells, as you apparently did, just to try them out. But this way, you did it for me! I still may have to try some. For the past year or so though, I've been using mostly Li-Ion cells, and have drifted away from NiMH in general. I'm sure I'll be back though!

Dave

 

[Yamabushi]

I took 8 Sanyo XXs new from the package and ran a Refresh on a Maha C9000 (Charge @ 1000 mA / Discharge @ 1000 mA): 2422, 2455, 2436, 2414, 2417, 2449, 2450, 2423 mAh.

Partially depleted them by use in a Fenix TK41 over 3 months and ran another refresh at the same Charge / Discharge rates: 2462, 2460, 2423, 2420, 2439, 2451, 2435, 2442 mAh.

 

[CaptCarrot]

Sorry to dig up an old thread, but I was linked here from a more recent thread.

I know they are not rechargeable, but would it be possible to show a graph that compares Energizer Lithium's a against the Eneloop's at the different discharge rates.

Cheers.

 

[HKJ]

Sorry to dig up an old thread, but I was linked here from a more recent thread.

I know they are not rechargeable, but would it be possible to show a graph that compares Energizer Lithium's a against the Eneloop's at the different discharge rates.

You could check my Comparison of AA chemistries.

 

[CaptCarrot]

Sorry, missed that.

 

[HKJ]

Sorry, missed that.

It is a bit difficult to find a specific thread. It would require somebody very dedicated to make an index of interesting threads.

 

[Battery Guy]

You could also check out the old Introduction to Ragone Plots thread. The Energizer Ultimate Lithium and Eneloop curves intersect at a constant power discharge of 2.5 W, or approximately a 1.2C discharge rate. So you get more total energy from the lithium cells for discharge rates less than about 1C (one hour), and more total energy from the Eneloops for discharge rates greater than about 1C. That's not really the whole story, but it is a decent rule of thumb to follow if maximizing runtime is your critical performance metric.

Cheers,
BG

 

[vestureofblood]

Great thread. Thank you for doing this.

 

[cj0]

Regarding the energy efficiency graph, that reads at discharge rates of 1.0A the energy [Wh] efficiency for each battery is within 90-95%:

When I have read correctly the batteries are discharged till 0.8V (my guess: voltage is measured under load, not during rest). Especially for this relative deep discharging, and 10mV -dV charging, I wonder how this leads to efficiencies over 90%.

I have used a SkyRC MC3000 HW>=1.3 FW=1.13, which has been calibrated/adjusted using an LMG95 DMM for voltage (near 4.2V) and current (near 1.000A) before doing a 3-cycle discharge/charge (D-C) on an almost new pair of low self discharge Ikea Ladda 23076/703.038.76 (made in Japan) 2450 mAh AA LSD Ni-MH batteries using the SkyRC charger its battery type "Eneloop", model "Pro/XX AA" program at default 0.5C charge (1.25A) and 0.25C discharge rates (-0.62A).

The measured energy efficiency (according to the MC3000) is:
battery 1: -3.050 Wh versus +3.644 Wh = 83.7%
battery 2: -3.038 Wh versus +3.707 Wh = 81.95%

How can this energy efficiency discrepancy be explained?
Isn't there a flaw in the energy efficiency graph in the starter of this thread?

Also: other source can only reach 92% charge/discharge energy efficiency for Ni-MH chemistry when using 50% of the SoC range.