Powerex AA 2700mAh NiMH Rechargeable Batteries w/holder- 4 Batteries Per Pack by Maha Energy Corporation
|
List Price: Our Price: $12.89 You Save: $5.06 (28%) Availability: Usually ships in 1-2 business days Category: Digital Camera See more digital camera details and other models |
|---|
Digital camera reviews of Powerex AA 2700mAh NiMH Rechargeable Batteries w/holder- 4 Batteries Per Pack
Digital camera Review: High Capacity Batteries.
Summary: 5 Stars
After charging these batteries using the Break-In/Forming charge on my Maha/PowerEx C-9000 charger, the actual AH ranged from a low of 2580mAH to a high of 2623mAH, with an average of 2599mAH. Although advertised as 2700mAH batteries, the manufacturer's published minimum guaranteed capacity is 2500mAH, of which they all exceeded.
After reading other reviews of this battery, I have not found the poor performance many others have experienced.
One conclusion may be that the batteries are being improperly charged. Improperly charging a battery is a sure way to damage it. Typically a battery can be charged two ways; either a trickle charge (with the typical overnight or 16 hour chargers), or fast charge (1, 2, 4, or 8 hour chargers).
When the battery approaches overcharge, a fast charger MUST reduce the charge rate. If the rapid charge rate is allowed to remain applied when the battery is fully charged, the battery risks damage, a blown overpressure seal, leaking electrolyte and so on. NiMH cells in particular are very sensitive to high overcharge current and can be easily damaged.
When a battery is trickle charged, the charge rate is not sufficiently high enough to damage the battery when it goes into overcharge. While charging for 16 hours is not as convenient, it is the safest method of charging, and will actually charge the battery to a higher capacity than a fast charger (unless the fast charger is a combination fast/trickle charger).
Since fast chargers must reduce their charge rate prior to going into overcharge, a method of sensing the battery's voltage, temperature, or a combination of the two must be employed so that the charger can detect when the battery is close to overcharge. For most fast chargers, there is a margin of of safety built into the charge profile so that the fast charge is removed well in advance of overcharge. This will result in the battery having less than 100% charge.
Some of the better fast chargers do switch to trickle charge at the completion of the fast charge to complete the charge. This still takes time, and often requires several hours of trickle charge to put a 100% charge into the battery.
Cheap fast chargers may not even sense overcharge, but simply provide a timed charge. With these chargers, unless the battery is fully discharged, the risk of high-current overcharge is significant.
The mechanism used in a fast charger to determine when a battery is at the threshold of overcharge is somewhat dependent on the manufacturer's battery design variances, battery capacity, and other factors.
Due to these factors, and efforts to keep charger costs low, a specific manufacturer's Fast charger may not be sophisticated enough to employ the proper circuitry to properly detect the overcharge point of another manufacturer's battery. Therefore, charging different brands of batteries on another manufacturer's FAST charger, while assumed as safe by many, may NOT safe in my opinion, and can cause battery damage.
One exception are the high-end Charger/Analyzers made by Maha/PowerEx and LaCrosse. These chargers use sophisticated overcharge detection circuitry to monitor voltage, changes in voltage, and temperature. Even then, if you incorrectly setup one of these chargers, you may still damage a battery.
Most battery manufacturers state that you will void the battery warranty by charging the battery improperly, which includes the use of other brand chargers. There is more to this than liability, there is a significant risk of battery damage.
However, it is generally accepted that overnight/16 hour/trickle chargers are safe for charging any brand battery, and notwithstanding any manufacturer disclaimer, may be safely mixed brand-wise. While there are always exceptions to even this convention, the charge rates are (hopefully) generally low enough that overcharging the battery will not damage it.
I am not sure why many folks are having problems with batteries, but perhaps it's due to improperly fast charging them.
To restate, I would never recommend FAST charging a battery on another manufacturer's FAST charger, unless it was specifically designed for that purpose (most of which are not).
Digital camera Review: Inflated specs
Summary: 3 Stars
I ordered a dozen, then immediately refreshed them to bring them up to maximum capacity. A Lacross BC-900 was used for the task. It takes about a week of constant charge/discharge cycles to complete a set of 4. The batteries maximum capacity was in the range of 2450 to 2590 mAh, with an overall average of 2530. This is somewhat short of the advertised 2700 mAh.
My prior purchase of NiMH AAs were Duracells listed at 2650 mAH. The actual capacity of these turned out to be in the 2600 mAH range. This was a few years ago and most will no longer recharge or don't hold a charge for very long.
I complained to Maha about it and the rep actually drew a dozen out of stock and proceded to refresh them on the Maha charger. It turned out that he got the same results as I did.
The good news is that he sent me the dozen he tested free of charge. Good customer service, but I hardly need that many batteries. I imagine that after a few years they will all need to be replaced.
Digital camera Review: Just another 'YES' vote
Summary: 5 Stars
Bought eight of these batteries and a MAHA charger (the C800S) back in 2007. I use them mostly for my Canon point and shoot camera, and honestly I just about never run out of battery power on the thing. I can go a month, easily, without a charge. They're so good that I'm getting spoiled - I just bought another fistful of them and a couple of the Maha Wizard chargers (Powerex WizardOne aa/aaa NiMH Battery Charger-Analyzer) to use for various other things around the house, like my headlamp and flashlights.
I really have to wonder why some people are having such bad luck with these. I believe they're the best rechargeable batteries on the market. Do some shopping around - other outlets offer these and sometimes the prices are pretty competitive.
In short, I think it's worth giving them a try just to see what kind of luck you have with them. To be fair, I've also got some Eneloops I bought on sale that seem to do pretty well...if you're not a heavy-duty user you probably ought to consider the lesser pricetag of the Eneloop brand. But if you need to go days and days without charging your camera batteries - on an overseas trip or similar - you just can't beat the Powerex 2700s.
Digital camera Review: Less than a year of reliability
Summary: 2 Stars
I have to agree with another reviewer who said that after less than a year of use, these rechargeable batteries begin to self-discharge rapidly. Over the last 3 years, I have used 20 of these Powerex NiMH rechargeable batteries for my digital camera, and every single one of them had this problem. Within the first few months of purchase, they were able to retain their charge for several weeks when they were not in use (even that is not long enough). Then their ability to retain charge declined gradually to the point that, after another few months, they couldn't even stay charged for a single day. Imagine that you bring these with you on your vacation and before you even get off the plane you realize they have all lost their power. And since they lose power so easily, you have to keep charging them probably more often than you need to, and that will shorten the batteries' lifetime even more.
I also suspect whether these Powerex batteries can actually give you "hundreds" of charges in their lifetime. I charged mine about 20 times a year in the last 3 years, and a few of them have degraded to the point that even my charger can't detect its presence.
I have a Powerex MH-C801D charger that is supposed to be able to recondition and "revive" these "dead" NiMH batteries. It will revive unchargeable dead batteries so they can be charged again (for another few months or so), at least that was what it did to my dead Powerex batteries. But it will not slow down their self-discharge rate.
If you need to keep spare rechargeable batteries that stay charged for long periods, my advice is not use these Powerex batteries and try those much longer-lasting Sanyo Eneloop batteries instead, which I'm now doing.
Digital camera Review: Less than a year use...
Summary: 1 Stars
Though they worked very nicely when I originally bought them less than a year ago, they no longer hold a charge AT ALL. I have kept them charged when not in use, switching out one pair for the next when needed in my digital camera. I just switched them over and the "fresh" set doesn't work at all now.