Best AA NiMH High Capacity Cells

[pobox1475]

What brand(s) and mAh is generally the best performing? It appears that they are now up to 2900 and I assume pushing the limit of what can be accomplished in the AA form factor. From what I recall all the 2500's were duds when it came to longevity. I don't want to make any poor investments.

 

[Niconical]

This thread will point you in the right direction

 

[etc]

This debate comes up from time to time.

I like Maha Powerex 2700 mAh.

Sanyo 2700 mAh is also pretty good.

 

[OpenGuy]

Out of the six Sanyo 2700 mah that I have, four developed rapid discharge syndrome within the first week of use - maybe they were like that out of the box. Currently, those four will all completely discharge within a week. They're OK if I use them immediately after charging, but they almost always need a full charge (about 2800 mah, so I'm guessing their capacity is now a bit less than spec).

I charge them on a Maha C9000. Initially, I did one break-in charge (270 mah by 16 hrs). Now I charge at 1.5 A.

All six cells were bought at the same time from the same (reputable) supplier. I can't see any physical differences on either the batteries or packaging between the four poor cells and the two good ones.

Could the break-in charge be damaging these batteries? In absolute terms, 270 mah is a lot more than the (say) 160 mah that would have been needed for the lower capacity batteries of several years ago. Any excess heat/pressure at the end of the break-in charge would still be confined to an AA cell, and be damaging thinner, weaker structures within the cell. I guess what I'm asking is why is 10% by 16 hrs the magical formula for a break-in charge, and will it always be so?

Back on topic, I am very disappointed in the Sanyo 2700 mah cells and won't buy them again unless I read that their quality problems are solved.

I just bought a pack of Powerex 2700 mah cells, which I hope will hold their charge better. Otherwise, I'll switch to LSD cells for everything.

 

[SilverFox]

Hello OpenGuy,

Welcome to CPF.

The 0.1C charge for 16 hours is "magic" because it is what the battery manufacturers use to determine the capacity of the batteries. It is considered a "standard" charge.

Often, the standard charge is used when determining cycle life.

The problem with high capacity cells is that they are fragile. Simply dropping them can do damage to the thin separator, and trigger high self discharge. Also, if these cells are not properly formed initially, there can be damage to the separator during normal charging rates.

The other thing to keep in mind is that you have no control over the care of the cells until you receive them. Fragile things often get damaged in transport. It will be interesting to see how the Powerex cells do.

You might want to consider contacting your supplier and see if you can get the high self discharge cells replaced...

Tom

 

[moldyoldy]

What brand(s) and mAh is generally the best performing? It appears that they are now up to 2900 and I assume pushing the limit of what can be accomplished in the AA form factor. From what I recall all the 2500's were duds when it came to longevity. I don't want to make any poor investments.

In my experience, the Powerex 2700 cells have survived usage well and have not developed a high self-discharge rate. They still test at ~2400mah on the Maha 9000 "charger" at a 1A discharge rate. Unfortunately I had to return 24 of the Sanyo 2700 AA cells - the supplier took them back quite gracefully w/in less than a month of receipt. the exchange was for Powerex cells.

What do I consider a high self-discharge rate? If the NiMh cell is unable demonstrate any useful capacity after a week, the cell is recycled. For any time between a week and a month, I may try some conditioning cycles at lower charge/discharge rates to recover some useful cell capacity. My normal recharge time for any cells in active use is a month whether they need it or not. Sometimes I check to see how much capacity is left.

In any case, for normal usage, I have almost totally switched over to the LSD Ni-MH cell.

 

[coppertrail]

I too have found that the Powerex 2700 AA cells to be my favorite. Low self discharge, higher than rated capacity. My favorite LSD cells are the eneloop. I too tossed out a set of Sanyo 2700 cells because of high self-discharge rate and diminished capacity after only a few uses.

 

[yellow]

During this year I have recycled most any of my 2300-2700 mAh cells because they have gone bad.
Initially, out of EVERY 4-pc pack of them, at least one cell was a bummer.
Now I am about to toss the final 8 cells I still had, because they dont even get to 1900mAh any more, even straight from the charger
(my charger discharges at about 500-800 mA, depends on setting, so much more "real" data than that the 2500+ mAh cells are tested)

On the other side, out of my 8 Eneloops, all are over 1900 mA, half of them over 2000, even when there is a week or more between use and charges,
same goes for the 4 "ready to use" Uniross Hybrio.
This kind of new Ni-Mh cells might "only" have 2100 printed on the outside but are much better when one uses the cells like me - grab them when needed, charge them when empty or a long use is planned.

Those 2700 (2800) mAh supercells should be better when taken from the charger directly upon use, but the chances there is a bad one, is there. Also with just short use they might get bad like mine (and like the cells of numerous users here also) did.

A good charger is of prime importance.

 

[pobox1475]

I did one break-in charge

Discharging before hand? I have heard that the "break-in" current is so low that it is not necessary. I how ever can not bring my self to charge a charged cell that long even at the low rate. I always discharge before any charging on my C9000. I guess I will have to give the Powerex 2700's a try for when I need more run time then Eneloops will allow. Thanks guys .

 

[OpenGuy]

Discharging before hand?

Yes, using discharge cycle on C9000. (I can't remember the rate, but it was probably the default 500 mAh).

Also, the cells came well packaged from a reputable supplier, and I didn't physically (or otherwise as far as I know) abuse them, so I'm disinclined to believe they're bad because of handling. At least, handling that we as consumers have any control over.

Looks like many others are also having problems with the Sanyos.

 

[josean]

.......

 

[odessit]

Just my limited observation

Yesterday I recharged my Sanyo 2700 that I used in a car light. (Fenix LD20)
After 8 months of standby and sporadic usage (typically in Turbo mode), the Sanyo 2700 were drained only ~1050 mAh.
I say it is pretty darn good.

These cells had probably 5 cycles on them (I used them for testing).
Survived upstate NY winter and 3 months of moderate summer.
I baby the cells, make sure that I do not drop them. However I do not baby them while they are in the light. LD20 has been dropped, banged and used as a mini-hand warmer in turbo mode by my wife.

 

[wildstar87]

I've had really good luck with the Titanium 2700 as well, they seem to keep their charge for quite a while, and still have capacity.

 

[Gazoo]

I too have found that the Powerex 2700 AA cells to be my favorite. Low self discharge, higher than rated capacity. My favorite LSD cells are the eneloop. I too tossed out a set of Sanyo 2700 cells because of high self-discharge rate and diminished capacity after only a few uses.

Same here...tossed out a set of 4 Sanyo 2700's. Never worked correctly from the start. I only use eneloops now.

 

[alfreddajero]

I also use the powerex 2700's but they dont seem to get over 2400mah.......still use them though on the night walks on the beach.

 

[tabetha]

I have used eneloops but now use only Uniross Hybrio, they average around the 2600mah mark, but some creep just over 3000mah, thye also hold the charge fantastically(when stored as their designed to).
I have a TechnoLine BC900 and BC700(same as la crosse), losing around 10% in 3 months of storage is good ?
tabetha

 

[Gazoo]

I have used eneloops but now use only Uniross Hybrio, they average around the 2600mah mark, but some creep just over 3000mah, thye also hold the charge fantastically(when stored as their designed to).
I have a TechnoLine BC900 and BC700(same as la crosse), losing around 10% in 3 months of storage is good ?
tabetha

There is no LSD AA cell capable of a capacity of 2600ma's...much less 3000ma's. The AA Uniross Hybrio has a listed capacity of 2100ma's. I believe you either have bad readings or your cells are regular NiMh.

 

[alfreddajero]

Another good cell that i like to use are the Duracell 2650's. I have stored my rc radio for half a year using them and I was surprised that my M8 would power up.

 

[tabetha]

Loads of my Uniross Hybrio score the 2500mah mark, I bought and changed specifically to Hybrio as not used for a long time but need to be ready when they are used.
They show the same value on both my BC 900 and BC 700 consistently over and over, so I've no reason to doubt it, not fussed anyway, so long as they do the job.
Whilst I concur they do state 2100mah, the 60 odd ones I have seem to rate well above this, as did the 100 + std nimh uniross before it, on other chargers as well, the 1300mah were typically 17/1800mah.
tabetha

 

[VidPro]

hey if your happy, some manufacture of clones in china is happy, and some e-bay seller that is ripping people off is happy, who are we to crash in on the party , and arrest everyone and send them home

they are trying to point out that to date, we have no knowlege whatsoever of any actual LSD cells made by anyone that rate or test over ~2100ma.
if you cells test at 2500ma it is very likly that they are 2500ma normal ni-mh cells that were a Fraud clone item, sold in various online locations.

they will not hold thier charge over time, especially after many charge discharge cycles.
and they are not "real" uniross hybrio things because the real ones have been tested Many times by many people (and thier fraud clones) and they rate like the real package says and are low self discharge.

What a party pooper and just to add to the misery, there are NO 3800ma ni-mh Sony batteries , they were 1800ma clones , sold on e-bay in a fake package, but not anymore, because everyone caught on to that one.

:mecry:Vote Nader