Recharging AA batteries - how?

[Overread]

I gots a new toy - and in the time honoured fashion of short, quickstart sheets its not told me quite how to use it....

I have a Powerrex MH-C9000 (also goes by the Maha brand name) and some
Energizer Rechargable 2500mAh
NH15 AA
1.2V NiMH HR6
In sets of 4 (set purchased as a single pack and kept with same 4 batteries all the time when cycling through the flash)

Those are all the details on the battery and because of their recent and past performance as well as history the "Refresh Analyze" (yes with a Z apparently...) mode is the one best suited to start trying to get some new life out of them. However the manual states that I have to enter the Charge and Discharge rate - however I am confused as to how I go about selecting the correct rates for each of these values.

[RandyS]

I have the same charger at home. I don't at all remember the numbers, but it seems to me they make recommendations for charge/discharge rates based on a percentage of the capacity of the batteries.

[Overread]

The manual does mention the battery capacity but makes no mention of how to determin this from the battery description. I know it has the mAh rating on the battery, but no mention of its capacity (as far as I can see- like 0.1C or 0.3C) and no mention of the mA rating on the battery either.

[lannes]

The manual does mention the battery capacity but makes no mention of how to determin this from the battery description. I know it has the mAh rating on the battery, but no mention of its capacity (as far as I can see- like 0.1C or 0.3C) and no mention of the mA rating on the battery either.

The mAH number is the batteries capacity, the default charging rate on the MH-C900 is 1000mAH, that roughly means it will take 2.5 - 3hrs hours to recharge your batteries from completely flat. In the refresh analyze mode, you just need to select the 1000mah charging default by selecting enter when it appears. The same for the default 500mah discharge rate and that's it. The cycle should be complete in about 72 hours.

[sapearl]

I have that charger also - quite a nice little unit - you just "cycle" through each of the batteries with the buttons, select your setting, lock them in, and move to the next. The readout info is quite helpful as it works its way through the charging and/or discharging process. It's also good at identifying bad batteries with a " high " indicator.

[Overread]

You sure its 72 hours?
Surely its (taking 3 hours as the recharge time as estimated):
3 hours recharge
2 hours rest time
6 hours discarge time
3 hours recharge time

At least for one cycle of recovery unless you are factoring in the 3 or so recomended recovery steps?

Also I think I just got the 0.1C part - they word and put it an odd way to describe a value for their own calculation when I was looking around the battery for the values.

[sapearl]

I did a total reconditioning on some three year old 2400maH Energizer batteries, and it did take quite a while - I didn't exactly count the hours but it likely was pretty darn close to 72 hours. The batteries were pretty "depleted" but the charger seemed to bring them back nicely.

You sure its 72 hours?
Surely its (taking 3 hours as the recharge time as estimated):
3 hours recharge
2 hours rest time
6 hours discarge time
3 hours recharge time.....

[RandyS]

I think that 72 hours may be pretty close. The recommend cycling several times on first charge, and if it's been a while (they've got a number in the manual for "a while) since the last charge cycle.

ETA: One problem with higher capacity batteries (like 2500 mAh) is that they don't shelf very well. Batteries like this are best used in an environment where they'll be used soon, and used fairly hard. Good for a strobe or something, but if you don't use it regularly you'll have to cycle the batteries again before you can use them - requires planning ahead. If you're using them regularly, they shouldn't require deep cycling/forming as frequently.

[Overread]

Thanks for the time pointers - I think I'll have to wait till I am not traveling in a day before I put them on charge if it could take 3 days!

Very true their shelf life is very bad on these energizer batteries. However the charger I was using before was also not doing them any good (one of those cheap quick ones that appeard to have no cutoff - so very easy for them to be left too long charging and they just discarge back out the excess). So I wanted a chance to give them a proper resetting and restoring. Chances are after that they won't get used much to be honest - I splashed out on 3 sets of Enloops (4 in each set) for their retention of charge - fantastic things for keeping charge - and of course I needed a good charger for them now (did not even want to put them near the other charger)

[canondslr]

I have those stuff, and they way I do it is:
charging rate: 1/2capacity = 2500:2=1250, rounded to 1300.
discharging rate: 1/4capacity = 2500:4=675, rounded to 700.

I got these from maybe more than a year ago, so I kinda not really remember about where did I got the info from, but I usually based on the instruction and some real life experience from some people who I think is knowledgeable.

Hope that helps...

[nduralt]

I gots a new toy - and in the time honoured fashion of short, quickstart sheets its not told me quite how to use it....

I have a Powerrex MH-C9000 (also goes by the Maha brand name) and some
Energizer Rechargable 2500mAh
NH15 AA
1.2V NiMH HR6
In sets of 4 (set purchased as a single pack and kept with same 4 batteries all the time when cycling through the flash)

Those are all the details on the battery and because of their recent and past performance as well as history the "Refresh Analyze" (yes with a Z apparently...) mode is the one best suited to start trying to get some new life out of them. However the manual states that I have to enter the Charge and Discharge rate - however I am confused as to how I go about selecting the correct rates for each of these values.

Ok, well I have the same readings on my Energizer batts. I'm not sure if this is the answer your looking for but I've been through 4 sets of these batteries over time and I usually throw them away when they get about 50% of their original charged value (ex. if the batt originally shot 100 pics fully charged, when I can only shoot 50-60 pics with the same battery I throw them away)... here's the deal:

I have the Battery Grip for my 7D, I use the energizers 2500mah in it when I run out of actual Canon camera batts (4 in total), believe me not that hard to do when camping for the weekend. I usually carry 18 additional energizer batts (I number them to keep track of them with marker and use 1-6 all together, 7-12, and 13-18 all in the same way). A set will usually last me about 600-800 shots (or 1.5-2.5 hours of video shooting) depending on the usage but usually on the lower end of the scale. The batteries will last me to 50% capacity and go through 50-100 recharges before that time. The recharge time on 4 batts is approximately 3 hours.

I hope at least some of these numbers you can use.