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

Reply
 
Thread Tools Search this Thread
Old Feb 26, 2005, 3:05 AM   #11
Senior Member
 
Join Date: Oct 2004
Posts: 141
Default

I've had the Energizer 30 minute charger for a couple of months now, and it's been perfect. It has no fan in it, but I simply use an external fan, just to be safe. It's really not a big deal at all to point a fan at the charger for a measly half hour...
EOS RT is offline   Reply With Quote
Old Apr 24, 2005, 4:21 PM   #12
Junior Member
 
Join Date: Jul 2003
Posts: 29
Default

It is generally known that heat and overcharging cells will ruin them. The 15 minute chargers have a fan to draw the heat away. If the electronics in the chargers are good then the charger will know when to terminate the charge for the cells.


I would say the chargers work. I have both the Ray O Vac and the Energizer 15 minute charger and have had no problems with my cells.
HaveBlue is offline   Reply With Quote
Old May 1, 2005, 12:01 PM   #13
Senior Member
 
Steven R's Avatar
 
Join Date: Apr 2005
Location: Tampa, Florida
Posts: 5,910
Default

Hi:

I have the Energizer 15 minute recharger and have been pleased with it. I bought it specifically for one of my digicams that uses AA batteries. I was tiredof always buying new batteries. Works as advertised, and the batteries last much, much,longer than the regular AAs in the digicam.

Even if I were to buy new rechargeableEnergizers batteries today, I would still be ahead of thegame moneywise. (Not to mention the time saved in notchangingcamera batteries so often.)


Steven R is offline   Reply With Quote
Old May 4, 2005, 12:30 AM   #14
Junior Member
 
Join Date: Apr 2005
Posts: 4
Default

I recently bought the 15 minute charger and 8 additional 2500 mah batteries to use with my new Canon S1 IS. I'm looking forward to a good experience with these on an upcoming vacation.

1) Is it OK to leave the batteries in the charger after they are done charging? Is there any benefit or harm in doing so? Is there a limit to how long I should leave them in?

2) Can I use NIMH other than Energizers in the charger? Should I expect similar results? I assume that the 15 min Rayovacs would not be compatible, but what about other "standard" rechargeable NIMH?

3) Does the charging take any longer if I have 4 vs. 2 or even 1batteries in the charger? Does the same generally apply to the other chargers other than the 15 minute model?

4) Does the 15 minute charger discharge the batteries before charging them?Is it OK if I don;t fully discharge them.

I read in other threads and even this one about the bc900. It looks really cool, but a little rich for me right now, thogh I am in for like $50 on the energizer 15 min including 12 batteries ;-)


Thanks,
John
jraggio is offline   Reply With Quote
Old May 4, 2005, 10:18 AM   #15
Junior Member
 
Join Date: Jan 2005
Posts: 20
Default

John,

1- It's OK to leave the cells in the charger. It has a trickle charge function which will keep the cells topped-off while they sit. The spec sheet for the charger shows a 24 hour charge limit, and I'm assuming this applies to the trickle charge, so it may shut itself off after the 24 hr point.

2-Any NiMHAA or AAA cells CAN be charged inyour charger,including,the Rayovac IC3 cells - I BELEIVE - but have notheard the specific resultsfrom anyone doing it. I personally also would not charge any super-cheap "off-brand" or very old cellsas they might not handle the high charge rate like newer, well made cells. Just my opinion.

3-The charge rate is the same (7.5A) no matter how many cells are in the charger.

4-It does not discharge cells before charging. With average use, the cells should be fine, however you will notice a significant increase in cell output after they are broken in (about 3-7 charges and discharges). Be careful discharging NiMH cells by doing things like leaven them in a turned on flashlight. Running them down in a manner like that can permanently damage them.

Also, the 2500mA cells will take slightly longer than 15 minues for a full charge.

-jeff


tbone-Ike is offline   Reply With Quote
Old May 4, 2005, 1:02 PM   #16
Junior Member
 
Join Date: Apr 2005
Posts: 4
Default

Jeff:

Thanks a bunch for the reply and the info. I assumed most of what you said, but wanted to make sure. The "spec sheet" that came with my charger was barely larger than a postage stamp. The Energizer site had an FAQ, but none of this was covered as far as I can tell.

I have 3 sets of batteries for the camera. I read that they lose 1/2 to 1% of their charge just sitting around. Have you experienced this? Is it cool to top them off before using them or is that bad for them? Is it safe to assume that the topping off would take less than 15 minutes if the batteries were charged before? The charger will never overcharge them, right?

Thanks,
John
jraggio is offline   Reply With Quote
Old May 4, 2005, 3:03 PM   #17
Junior Member
 
Join Date: Jan 2005
Posts: 20
Default

John,

What you've read about self-discharge is true, but I personally think it's typically overall less than 1% per day and closer to the 1/2% or less.

Topping them off works well and will indeed only take a few minutes. It won't harm the cells at all. It's recommended that you cycle NiMH cells maybe every 10-15 charges or so. In other words, you probably wouldn't want tohave a spare set that just sat around and you did nothing but top them off every month for a year without actually 'using' them.

That's one thing that's really great about NiMH cells is being able to keep them charged and just pop them in for afew minutes when you need them.Since I use a slower charger, I do this quite frequently :-)

Your charger won't overcharge cells; it uses a common chargertechnology called delta-v which senses when a cell has reached a full charge and terminates the high-current charge.

Don't know if you've used rechargeable NiMH's before, but (especially) after they've been 'broken in', I think you'll be pleasantly suprised at how long they last compared to alkalines, not to mention you can re-use them hundreds of timessaving yourself ALOT of money and trips to the store It's all about the discharge curve.

-jeff



tbone-Ike is offline   Reply With Quote
Old May 16, 2005, 4:34 PM   #18
Junior Member
 
Join Date: Mar 2004
Posts: 3
Default

tbone-Ike wrote:
Quote:
John,

2-Any NiMH AA or AAA cells CAN be charged in your charger, including, the Rayovac IC3 cells - I BELEIVE - but have not heard the specific results from anyone doing it.
I have the both the 15 minute Energizer charger and the Rayovac IC3 batteries, and I have never gotten the IC3s to charge successfully in the Energizer charger.
BigWaveDave is offline   Reply With Quote
Old Jun 9, 2005, 9:28 PM   #19
Senior Member
 
Join Date: Feb 2003
Posts: 107
Default

jedi_master wrote:
Quote:
So what it reduces the cycle life. I personally don't want
to use the battery for more than 3 years. By then
there will be 3000 mAh batteries. The real concern
should be how complete it can charge. It has been
reported that the 15 minute charger from Rayovac can charge
about 85% of the capacity. I hope the energizer charger can
do better.
I agree with that philosophy. The comvenience of a 15 minute charging outweighs say a 25%or other reasonable reduction of battery life. I don't know why some poeple obsess about maintaining maximum battery life - nice to have long battery life but what's the big deal?
rodmeister is offline   Reply With Quote
Old Jun 10, 2005, 9:45 AM   #20
blr
Senior Member
 
Join Date: May 2004
Posts: 339
Default

rodmeister wrote:
Quote:
I agree with that philosophy. The comvenience of a 15 minute charging outweighs say a 25%or other reasonable reduction of battery life. I don't know why some poeple obsess about maintaining maximum battery life - nice to have long battery life but what's the big deal?
It's true that with today prices of rechargeables it is no big deal moneywise. However, these 15 min chargers both shorten the cycle life while still not charging the cells completely, so after a year or so tyour cells will discharge only 50-60 % after being charged in the 15 min charger. This is unacceptable for me. IMO it all depends on your usage pattern. I have couple of pro photographer friends who love these 15 min chargers for their flash units. For them it's cruicial to be able to get fresh cells fast when on a job if they run out of power. For me it is not important and I prefer to charge slower it's safer, more complete and the chargers are more compact (matters when travelling).

Using a fan can aid heat dissipation, but does not prevent overcharging. The pressure inside the cell is still high and the active material is degrading. It is little known that it is not recommended for NiMH cells to be charged with -dV method. Sanyo for instance states in their technical literature that -dV can be used but the cycle life will be reduced by about 20% based on 1C charging rate. At 4C this shortening is perhaps 50% and more. NiMH cells are properly charged by either 0dV (peak voltage detection) or dT/dt (temperature gradient) methods. Since these are more expensive to implement 90% of todays chargers use the inferrior -dV technique thus overcharging somewhat. A NiMH cell is fully charged when the voltage reaches a plateau just before the drop occurrs. After that most of the current pumped to the cell is converted into heat (the pressure inside the cell increases sharply too) and the voltage drops due to increased resistance.

How much overchrarging depends on the sensitivity of the IC in the charger. The charger should be able to detect a small voltage drop in order to avoid gross overcharging. Sanyo recommends 10mV or less of voltage drop per cell. Some chargers cannot sense this and continue to charge until a drop of 20-50 mV per cell occurrs. By that time the cells have reached an unhealty temperature say 50C and more at currents above C/2.

The funny thing is that some manufacturers claim and advertise their products as "cool" chargers while their are exactly the opposite.

When one calculates charging times the cooling time should also be taken into account. Say if a I'm to use a 30 min charger that heats up the cells to 55C at the end of charge, I wouldn't put cells so hot in my camera right away. First the risk of venting inside the camera is big and second it will heat up the camera electronics. I'd wait for 20-30 minutes for the cells to come back to room temperature before using them. Instead of this I'm using a charger that charges in about 60 min and the cells come at room temperature so I can use them right away.


blr 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 5:39 PM.