Go Back   Steve's Digicams Forums > Digicam Help > Batteries or Power Packs

Reply
 
Thread Tools Search this Thread
Old May 26, 2006, 12:19 PM   #11
Junior Member
 
Join Date: May 2006
Posts: 16
Default

I am busy running a series of tests on my 2 sets of 2500mAh Energizer batteries (also for my Canon A95).

When purchased, they were astonishing...and they still are to some degree.

I can get 2300mAh (about 11W/h) out of them using a similar setup as on Imaging-Resource's The Great Battery Shootout. This drains the battery pack to 4V (1 volt per cell) at a constant current discharge rate of 1A.

Straight out of the charger, and into the discharger I can get 2300mAh, as good as the MAHA 2500mAh batteries. However if you leave the batteries for 1 week after they are charged, they are about 50% discharged. In fact a set that I left for 3 weeks (at room temerature, it's cold here in the UK) were actually so flat that the terminal voltage of the 4 cells was 3.98V...which indicates that theywere completely flat.

These Energizer batteries are almost new, the one set has had exactly 8 charge/discharge cycles.

My 2500mAh MAHA set on the otherhand managed to take 270 photos with the flash and LCD on over a 2 week period...something the Energizers can only dream of.

Conclusion: The Energisers are capable of delivering the quoted 2500mAh right out of the charger, but the self discharge rate is in the order of 7% per day of the remaining charge. To me this makes them pretty useless batteries. What is the point of having fantastic power but have to use it within a week? I'd prefer 2000mAh batteries that can maintain 80% of their charge after a month likeMAHA and Sanyo.

Good thing I realised that as I was about to recommend them to a friend.

Attached Images
 
StuartP is offline   Reply With Quote
Old May 26, 2006, 1:33 PM   #12
Junior Member
 
Join Date: May 2006
Posts: 26
Default

StuartP, what charger do you use and what NiMH's do you plan on buying next?

A wind of caution on your set-up, since you're testing the set in series you may over-discharge a cell or 2.

I'm currently refreshing my other Energizer sets that are used in other devices such as a radio, toothbrushes and flashlight and will report on them here.
yawglenn is offline   Reply With Quote
Old May 26, 2006, 2:18 PM   #13
Junior Member
 
Join Date: May 2006
Posts: 16
Default

yawglenn,

Initially I used the Quick Charger that came with the Engergizers (60 minute charger). The batteries used to get quite hot (within spec., but still too hot for my liking).

Now I use the MAHA MH-C401FS, which also gets them quite hot on fast mode but much gentler on slow mode it also trickle charges them better/fuller.

I am only discharging the cellsat 0.4C (1000/2500) and cutting off the voltage at 1.0 Volt per cell, this is well within the battery's specification (battery voltage is sampled 256 times per second).

The discharger I built was initially used to test pulsed/profiled discharging so that I could simulate the battery use in a typical digicam...i.e. 1000mA load for live LCD/recording, 1500mA load for flash charging, 0.5A for review, then monitor the battery volts for fluctuations. However the actual problem that I have is the self discharge, not the ability to deliver instantaneous current.

Thanks for the caution, likewise asmall note of caution to yourself...be careful discharging the cellsinto torches and toothbrushes as they do not have any voltage cut-off and will deep discharge the cells.


To answer your last question...I just bought4x 2700mAh Sanyo.

Attached Images
 
StuartP is offline   Reply With Quote
Old May 26, 2006, 4:28 PM   #14
Senior Member
 
Join Date: Jul 2005
Posts: 358
Default

Hello Yawglenn,

Interesting observations... Let's take a moment to look at the math. You seem to have a lot more batteries than you can use at one time. If I understand you correctly, you have 4 sets of 4 cells. Each set is (when new) good for around 250 pictures. That means that you start the day with the capability to shoot around 1000 pictures. However, in two years of shooting, you have only shot around 7000 pictures. This means that your cells have been "in storage" for most of their two year life. The worst thing you can do with NiMh cells is to store them. They are happy when they are being worked to death.

As NiMh cells age, their ability to hold voltage under load goes down, and their self discharge rate goes up. You have given enough information to suggest that both your Panasonic and Energizer cells are ready to be replaced. The current NiMh chemistry is seeing around 0.7% self discharge per day. Your Panasonic cells are showing around 2.5% per day, and of course the Energizer cells are way above that.

A little more math to consider... You have around 7000 shots on around $36.00 of batteries. That works out to a little over $0.005 per shot, which is still cheaper than film...

I suddenly realized that there are even more numbers for consideration here. With a set of batteries good for around 200 shots and if we take your 7000 shots and divide it by 4 we come up with around 8-9 cycles on each set of batteries. To have batteries only last 10 or fewer cycles is not good.

For the record, I had a set of Energizer 2300 mAh cells that developed high internal resistance (they were also bought at Wal Mart, if we decide to put them on the spot). I also have Energizer 2500 mAh cells that were recently tested as having around 37% of their initial capacity after 6 months of room temperature storage. You may find this thread informative.

I am not against having a stockpile of batteries to draw from, however you need to take care of them while they are in storage. The best storage advice I have run across is from the makers of the Schulze chargers. They suggest storing cells after discharging them (at 1 amp) down to 1.0 volts. When you take the load off the cell, it jumps up to around 1.22 volts. In this condition, the cell is good for 30 days. After 30 days, you charge it back up, then discharge it back down, and it is good for another 30 days. When it is time to use your cells, you simply charge them up and use them.

Schulze is serving the RC hobby industry and is going for maximum performance from your batteries. People who follow these instructions end up winning races and are quite please with their battery pack performance.

The question comes back to "Why are your batteries dieing after 10 or fewer cycles?"

I am not sure I have an answer for you, but would suggest you contact Energizer and see if they will replace your high self discharge cells. Two years is pushing things a bit, but only 10 cycles should get their attention.

By the way, Eneloop cells can be charged on any NiMh charger. Their chemistry is a bit different, and they actually like to be stored at full charge. The lower capacity makes the cell more robust, and it is supposed to be good for around a thousand cycles. The normal Sanyo 2500 mAh cells are supposed to be good for 500 cycles, but are unable to power up my camera after 150 cycles suggest that the test methods may differ from real life, but they should still get more than 10 cycles.

Tom
SilverFoxCPF is offline   Reply With Quote
Old May 26, 2006, 4:32 PM   #15
Senior Member
 
Join Date: Jul 2005
Posts: 358
Default

Hello Stuart,

It sounds like you have a bad cell. Have you checked individual cell voltage?

Tom
SilverFoxCPF is offline   Reply With Quote
Old May 26, 2006, 4:46 PM   #16
Senior Member
 
Join Date: Mar 2005
Posts: 1,870
Default

Tom,

Where did you buy the eneloops?

the Hun

rinniethehun is offline   Reply With Quote
Old May 26, 2006, 5:00 PM   #17
Junior Member
 
Join Date: May 2006
Posts: 16
Default

Hi Tom,

Yep, the voltage ofevery cell can be tested individually in the rig with or without a load from 0mA to 2550mA.

Each of the 8 cells (2 marked sets of 4) measure (roughly) the same voltage before during and after discharge.

As mentioned, I can get the full mAh rating out of the batteries fresh from the charger, but the self discharge is extremely high for all of the 8 cells.

Both sets act the same, the only conclusion I can draw is that all 8 cells are faulty or Energizer are not truthful about the self discharge, up until this discovery I was an Energizer fan (especially alkalines), perhaps it is a bad batch or even counterfeit product, either way I won't be buying Energizer again. Even my Uniross 1700mAh 4 year old batteries are more useful to me at this point.
StuartP is offline   Reply With Quote
Old May 27, 2006, 2:32 AM   #18
Senior Member
 
Join Date: Jul 2005
Posts: 358
Default

Hello The Hun,

I just happened to have a friend traveling through Japan who knew I was interested in batteries. He got in touch with me and I had him pick up several sets for me to play with.

I believe Sanyo was scheduled to release them in various other areas, but for some reason the release date has been pushed back.

Tom
SilverFoxCPF is offline   Reply With Quote
Old May 27, 2006, 2:36 AM   #19
Senior Member
 
Join Date: Jul 2005
Posts: 358
Default

Hello Stuart,

I suggest you contact Energizer, explain what is going on and get some replacement cells.

Tom
SilverFoxCPF is offline   Reply With Quote
Old May 27, 2006, 10:30 AM   #20
Junior Member
 
Join Date: May 2006
Posts: 26
Default

SilverFox, thanks for your through reply. Right now I'm away from my home computer & using my PDA so I keep it brief.

I use 2 sets for my camera - Energizers & Panasonic's w/ a set of Energizer lithium's as back-ups. The other Energizers run in other devices. I have kept a log of battery usage but did not want to bother posting it or going into it here initially. However I merely summarized my impressions, which was over the 2 1/2 years I used the camera I had taken about 7000 shots during which I've had to replace the Energizers. albeit the first replacement was due to changing from 2300 to 2500 mAh. I did notice the 2300's performed poorly when transferred to a flashlight. Subsequently the 2nd set the 2500's cycle to cycle slowly diminished and I transferred those to another flashlight and got a 3rd set which I'm now using and will report on soon.

Now during all this time I still have the Panasonic's which showed some decline and they responded well to refreshing (i recently got the BC-900) and look like they'll perform at a level close to when new (I'll report soon).

Also as my shooting varies such that I may recharge in 1 day or 1 month.

Since you suggested I contact Energizer I might if I could find the time but having this experience I may just settle with an alternate.

I may add more on this when I get home. Btw I thank you for your contributions on the boards, very informative, especially on the BC-900 & the shoot outs.

StuartP, thanks for your reply. Yes I'm well aware of the danger of running the batteries in torches as I started with Ni-Cad way way back - now if only I could get my wife to understand that as she had let her night reading torch run down a few times. I'm in the process of refreshing them now. This set Energizer 2100's have served me well and have not shown the severe decline of the sets used in the Canon A95.

Now I just wasted all this time punching with a stylus on a PDA thanks guys!

later
yawglenn is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 8:57 PM.