Thanks for the reply. Charger model is the Energizer CHP41US. I disabled the beep and the backlight is on most of the time; it runs till it shuts off.
That's not really the best idea - it is better to heed the warning beep. The reason for this is that while you can get a few extra minutes out of the cells by disregarding or disabling the beep, you are taking the cells below 0.9v (discharged) into "flat" territory. Quality cells can recover from this, but it is not good for cycle life.
Not too many good reviews for the CHP41US on Amazon.
I'm glad you saw that, especially the reviews from the engineer who put them through their paces with a LaCrosse battery analyzer. He has reviewed quite a few drugstore quality chargers. The biggest thing to look out for is the ability to work with odd numbers of cells, and a quality delta-v charge shutoff detector. Maha's and LaCross have these qualities. So do some drugstore chargers, but many are either out of production, or have hard to find specs.
Looks like it's a 2 or 4 at-a-time charger. I'll return it and try the MAHA MH-C401FS. Do you recommend the compact wall version for the same results as the Maha PowerEx H-C401FS4AA27? While I prefer small and light, performance is important too.
Those appear to be the same thing, but one includes the Powerex 2700's as the included batteries. While the 2700's are useful, you'll want to be using them within a few days of recharging. The tradeoff for very high-capacities like 2700ma, is that they have a higher internal resistance, hence high self-discharge rate. You'd want to use them right away. Photographers like to charge them just before a shoot, rather than having them sit around for a week. And, when measured, you may not really get 2700ma out of them, but something lower that may meet the minimum manufacturer spec.
One tip for Maha CH-401FS users is that it has a slow (300ma) and fast (1000ma) charge rate. With larger capacity batteries of today (the 401FS is quite a few years old now), to accurately detect the delta-v shutoff, use the fast rate. If you use the slow rate with high capacity batteries (anything 2000ma or more), it may not detect the delta-v, or take a much longer time than necessary to do so.
Warning! Not all Maha chargers charge cells individually either! You have to check.
My other question is do I stick with the lower 2250mAh stock GP's? What are the performance differences for the Sanyo 2700's for example? I've read great reviews on them.
In real-world use on a low-drain scanner (unlike a high-drain flash unit), they are about the same, however keep in mind that the Sanyo's might also have a high-self discharge. Use them pretty quickly after recharging. I have no experience with the REGULAR Sanyo's although Sanyos on the large are very high quality.
One option that is popular is to use "pre-charged" or "low self discharge" batteries - the most popular being Sanyo Eneloops. They have a low-self-discharge, but usually have a lower overall capacity of about 2000 to 2300 mah. For me, the low-self-discharge is a secondary benefit. The primary benefit of the LSD cells, is that they typically have a lower internal resistance - thus they charge faster and cooler. (That's a comparatively coolER - they still get hot). And unlike regular nimh cells, they are much closer in capacity to each other being made with higher quality standards. I've also found that they don't need a lot of recharge cycles to get them up to speed. Neither do they seem to need "forming" charges. In other words, one or two rounds of charging, and you are good to go.
Also look for fresh cells. I was very excited about finding "Duraloops" - slang for rebadged Duracells that are really Sanyo Eneloops underneath. (White tops). I bought a bunch, only to find that they are already 3 years old! They are performing fine, only they have about 1850-1900 ma capacity. Not bad, but I should have been more careful about buying new-old stock.
Avoid any charger that is faster than about 2 hours, unless you have experience and the equipment to carefully monitor them. Funny thing is, you can do about as much damage from a "15-minute" charger, as you can from just "slow roasting" a battery on so-called untimed trickle chargers. It just takes longer to degrade them.
