Ideal current to last longest # cycles in AAA Duraloops

[InHisName]

I have been charging my AAA Duraloops at 500ma in my C9000. In the course of 30 weeks at average of once ever 6 days charging, I now am seeing some deteriation in the ability to deliver higher currents compared to when new. i.e. the impedance has increased a lot. Another 30 weeks of this and some might even show HIGH when I attempt to charge them.

That would make it around 65 cycles. A FAR cry from 1000 or even 500 !

They are powering a set of Motorola FRS handy talkies. Three days 10.5 hours a day 'on' with no or little usage. 31.5 hours total and battery indicator is showing "low". I recharge them at 500Ma each and fill about 770MAH approx. It sometimes is as low as 675 and upto 835Mah.

Is there a 'better' charge rate, than my 500Ma, to gain LONGER lifetimes out of my Duraloops ?

 

[brted]

Have you tried doing a refresh/analyze on them? Or even a break-in? 500 doesn't seem unreasonable at all to me. Maybe you could recharge them more often so they aren't getting full cycles.

 

[Black Rose]

Maha recommends doing a break-in every 30 cycles.

I normally charge my NiMh cells at 0.5C, or 400 mA for Eneloop/Duraloop AAA cells.

 

[InHisName]

Have you tried doing a refresh/analyze on them? Or even a break-in? 500 doesn't seem unreasonable at all to me. Maybe you could recharge them more often so they aren't getting full cycles.

I ran a break-in back around week 20 or so on ALL 12 cells. I also worked over two of the worst performers with refresh/analyze 5 cycles. Then another breakin. STILL no improvements. Then again, they didn't suddenly get worse either!

 

[VidPro]

sounds good for your charging.
the things that goes wrong with these little creatures for ME, the devices they go in are multiples in series. and they operate till one battery is fully discharged (which can incurr some reverse charge in some devices).
and the tiny things even enloop cant handle it for crud.

so if you wanted to SEE possibly why everything goes bad on you even though you got the rest going as best as you can. Test the voltage of each cell after a full use of them in the device. is one of the cells WAY low or even at 0 ?

it isnt you, its them

with my Direct drive 3xAAA lights i dont have such low discharge issues, because the led peters out before the batteries do.

 

[45/70]

In addition to what Vid said, I'll add that in my experience with AAA NiMH cells, the AAA's don't hold up as well. I think it has to do with their diminutive size as compared to the larger versions. Miniaturization necessitates compromise, and they just don't last as long as AA's. While most of my experience has been with non LSD versions, I wouldn't be surprised if the same holds true with LSD AAAs.

I recently did a "break in" of 4 AAA eneloops on a C9000, and they all came up at over 800mAh. These cells are dated 8/06, but really don't have many cycles on them and have been well cared for, so it doesn't really mean all that much.

Dave

 

[McAllan]

I believe there's one or two causes for the "HIGH" AAA in C9000.

First of all the C9000 tortures the cells in order to measure Ri (internal resistance). Odd to me since other chargers manages this without such torture. Secondly it demands values which is on the edge of realistic to demand for an AAA cell - it doesn't distinguish between AAA and AA.

Many cells rejected by the C9000 works fine in other chargers for a very long time and seems to perform quite well none the less

So get another charger for AAAs. Perhaps even the infamous LaCrosse (be sure to get one with a new power supply so it won't go )

Or for folks in Europe ELV has another small charger (Akku ViewAV-4D) which has many of the same features as C9000 and LaCrosse and of course the Conrads. Or many cheaper chargers can do if one doesn't care about a capacity read out (the C9000 can still be used for discharge checks).

 

[TakeTheActive]

...the C9000 tortures the cells in order to measure Ri (internal resistance)... ...it demands values which is on the edge of realistic to demand for an AAA cell

Please explain.

...other chargers manages this without such torture...

Please post examples, with LINKs if feasible.

Thanks!

 

[McAllan]

Please explain.

The Ri measurement is to ensure you're not trying to charge alkalines or very weak rechargeables.
Take a look at this post by Bones. Here you can see that the charger got no way of detecting whether it's charging an AA or AAA. I have done some rudimentary measurements prior to this post. For about 10 seconds it does this test draining 2 A into an AAA even if you only want to charge it with 200 mA.
Probably not so rough as I first thought but none the less still IMHO a bit on the rough side with >2C.
I know you can get ultra fast chargers which charges AAA over 2C but they really wear the cells. Even AA has their lifetime shortened.
OK, you don't usually choose 2 A for charging but it is done in relative long pulses in contrast to says the Conrad which pulses really fast.

Guess though it's not as rough as I first though, granted, but could wish for a little faster pulsing none the less.
But I still maintain my view that the way it's doing it's Ri measurement and rejecting criteria have quite some room for improvement.

Please post examples, with LINKs if feasible.

Thanks!

Sorry I don't have the equipment to do more detailed measurements. But as examples I can put my various cheap GP chargers. They reject an alkaline right away while they have no problem charging some older AAA non LSD NiMH which the C9000 rejects and seem to work fine otherwise. And the GP's don't dump 2 A into AAA over 10 sec. to find out.