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hi guys,

i know there are a few guys on here who know their stuff about batteries, so i thought i'd post a question.

i have 4x 2650mah duracell (1st gen i think, whole battery is green and black) and they have been great. i treat them badly, leave them in the flash up to a week at a time and they always seem to have plenty of charge whenever i fire up the flash.

recently i bought a new set for a friend, of identical batteries but these have a copper top on them. ends up he didnt need the batteries so they are mine to use, but they wont hold charge! although they have only been charged maybe 1 or 2 times, when i put them in the flash there wasnt enough voltage to fire it up. they have sat on my desk for 1 week and i would have expected them to have some juice in them.

the older duracell left in the flash for a week are starting to go flat, and are all reading 1.1v except for one reading 0.95v. the new duracell without any use read 0.9v across all 4, they had a full charge about 1 week ago.

is this normal?

I have learned not to trust either Duracell or Energiser rechargeables. They do not, in my experience, live up to their claimed capacities, even when new, and go downhill from there fairly rapidly.

I use a LaCrosse intelligent charger that indicates capacity on charging. I found that the two brands mentioned above would be consistently more than 10% below stated capacity, and more than 25% below after a year.

These days, I use PowerEx brand batteries as I have found them to be consistently conservatively rated. The imedions I use now have all shown to be be 0 to 15% ABOVE their stated capacity. I haven't done a year later test yet. I buy them from Jeff at Servaas. Pretty sure there is a link to his site from the front page. If not do a search to find it.

In your case, I would guess that you would be better off with lower capacity long life cells, rather than maximum capacity. The ones to consider are Imedion, made by Powerex - the ones I use and Eneloop, made by Sanyo.

Basically, the very high capacity cells are made in a way that stores more charge, but in such a way that they self-discharge quicker. If you are a sporadic user, and your post indicates you are, then these slow discharge types are more likely to be working when you want them.

EDIT: Check the country of origin on your cells. I'll bet the old ones are Japan, and the new ones are China. You might try using a refresh charge on them. My LaCrosse does this, as does the Maha9000 that Jeff sells.

Cheers for the advice Mr Darcy, my next purchase will probably be of a different brand when these batteries start to get tired.

I dont have a good battery charger like the one you mentioned, but i have put the batteries in a trickle charger which should be more forgiving than the 2hr charger that i have. i'll try to give the batteries a workout and see if they improve once they have worn in.

Perhaps some lower capacity longer lasting cells would be a good idea. What is the usual power falloff per day for the high capacity batteries?

there is a discussion of this earlier, which led me to buy the powerex charger and battery

viewtopic.php?f=17&t=31955

Philip

thanks sevencolours, i saw that thread a while ago and couldnt find it again (i'll admit to only doing a brief search)

I dont have a good battery charger like the one you mentioned, but i have put the batteries in a trickle charger which should be more forgiving than the 2hr charger that i have. i'll try to give the batteries a workout and see if they improve once they have worn in.

The most important thing to look for in a charger is "Delta-V" This basically means that the charger monitors the batteries under charge, and shuts off the current when it detects they are fully charged, no matter how long it takes.
The LaCrosse and Maha do this, and in addition have special programs that allow for the reconditioning of weak cells.

The cheaper (to make, not necessarily to buy) systems use a timer to turn off the current. Fine if you use fully discharged batteries that the charger was designed for, but if the batteries are only partially discharged, or are lower capacity than expected, then you cook the batteries. This results in their destruction fairly quickly. OTOH, if the batteries are higher capacity than expected, the cells are never fully charged.

As well as the two brands I mentioned above, I believe Jaycar sell a Delta-V charger. There are sure to be others.

wider wrote:I dont have a good battery charger like the one you mentioned, but i have put the batteries in a trickle charger which should be more forgiving than the 2hr charger that i have. i'll try to give the batteries a workout and see if they improve once they have worn in.

If they are not holding charge from the outset, there is not much hope for improvement. Cells do improve capacity after the first few cycles, but self discharge will not improve.

Perhaps some lower capacity longer lasting cells would be a good idea. What is the usual power falloff per day for the high capacity batteries?

When healthy, and stored at 20C, about 10% per month. Lower quality cells will be more like 30% per month. Both good and not so good cells will tend to have higher self discharge as they get older. Higher temperatures also increase self discharge. NEVER leave your batteries in the car in summer.

servaasproducts wrote:When healthy, and stored at 20C, about 10% per month. Lower quality cells will be more like 30% per month.

Hard to say for sure, but the Imedion AA in my Nikon SB800 would seem to last longer than this even. Not sure when they went in, but would be at least 9 months ago now..... and still worked well in Feb & April when they had a run when taking photos indoors..... sure they were in - in Oct at least, if not earlier.

I suppose I should put 4 of the 5 on the chargewr and give them a discharge & recharge cycle.....

Higher temperatures also increase self discharge. NEVER leave your batteries in the car in summer.

Well, that would be in their favour in Tassie.... worst temp they have ever seen would be either a charge cycle in the Maha charger or the max temp of 34 degrees for a day or 2 this summer.....

who wrote:

servaas wrote: Higher temperatures also increase self discharge. NEVER leave your batteries in the car in summer.

Well, that would be in their favour in Tassie.... worst temp they have ever seen would be either a charge cycle in the Maha charger or the max temp of 34 degrees for a day or 2 this summer.....

Just bear in mind that a car sitting in the sun will get MUCH hotter than ambient. I have seen 45 degrees in my car when ambient was 23.

Incidentally, cool temperatures work in favour of solar panels too. They are much more efficient at low temperatures. A pity your government doesn't allow feed in tariffs. They wouldn't need another Hydro system if there was significant take up.

who wrote:

servaasproducts wrote:When healthy, and stored at 20C, about 10% per month. Lower quality cells will be more like 30% per month.

Hard to say for sure, but the Imedion AA in my Nikon SB800 would seem to last longer than this even. Not sure when they went in, but would be at least 9 months ago now..... and still worked well in Feb & April when they had a run when taking photos indoors..... sure they were in - in Oct at least, if not earlier.

Yes, the IMEDION have a much lower self discharge rate than normal rechargeable batteries, around 15% per year. They are perfect for those of you who don't use the flash every day. I'm not a pro, so I am not shooting every day. For this reason I tend to use IMEDION in my K100D and AF-360 rather than Powerex 2700's.