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Re: What's your battery system?

PostPosted: Nov 27, 2009 7:44 pm
by Tenzin Beck
A Battery Guide for Dummies would be an excellent thing to post here. I'd even say it would deserve being stickied.

Re: What's your battery system?

PostPosted: Nov 27, 2009 8:12 pm
by Chads93GT
I agree. I use the duraloops and the lacross bc900 charger, every so often I refresh the batteries or test them, most of the time i recharge them on the lowest setting to keep the heat down. Other than that, I really dont know what all that means, but I do know that a few of the energizer cells i have tested are crap!

Re: What's your battery system?

PostPosted: Nov 28, 2009 2:41 am
by harrym
MHC9000
Image

The last smart charger I had didn't allow for individual battery selection, this one does.

My flash specifies that I have to use NiMH <1,000ma because of gas build-up (the unit is air tight and waterproof), not "overheating" as I stated before. I use the higher capacity batteries anyway, you just gotta point the flash cover away from people when you unlock it.

I bought 20 Eneloop 2000ma batteries: 8 for my focus light, and three sets of 4 for the flash. I'm going with lithium-ion in the camera.

Re: What's your battery system?

PostPosted: Nov 28, 2009 5:51 pm
by YuccaPatrol
The MC9000 charger pictured above is a very very very nice thing to have. Among its many features, it allows you to actually test and KNOW the true capacity of the rechargeable batteries in your backup cave diving lights :rofl:

But of course, being able to KNOW the actual capacity of the batteries in your backup lights that you trust your life to is something to be ridiculed. . . :laughing:

Re: What's your battery system?

PostPosted: Nov 28, 2009 8:26 pm
by Marduke
Chads93GT wrote:I agree. I use the duraloops and the lacross bc900 charger, every so often I refresh the batteries or test them, most of the time i recharge them on the lowest setting to keep the heat down. Other than that, I really dont know what all that means, but I do know that a few of the energizer cells i have tested are crap!


Charging on the lowest setting is actually quite bad for the cells. Smart chargers need a -dV signal to sense termination. To generate that signal, cells need to be charged at 0.5-1.0C. Charging at less can lead to missing the termination, and overcharing the batteries. So charging at 200mA will likely lead to reduced performance and life.

PS, I am writing a "Battery 101" guide for my grotto newsletter. I will also post the contents here in this forum when it's completed.

Re: What's your battery system?

PostPosted: Nov 28, 2009 8:38 pm
by Chads93GT
I think you told me that once. Usually i charge at 1000 mah, but i guess you mean anywhere between 500 and 1000 mah on the lacross charger is fine?

Re: What's your battery system?

PostPosted: Nov 28, 2009 9:17 pm
by Marduke
Chads93GT wrote:I think you told me that once. Usually i charge at 1000 mah, but i guess you mean anywhere between 500 and 1000 mah on the lacross charger is fine?


0.5-1.0C relates to capacity. For a 2700mAh cell for example, that would mean the ideal charge current is 1350-2700mA.

With the BC900 and AA Eneloops, I find 700mA to 1A works well, since the the BC900 tends to be a "hot charger" by using PWM instead of constant current.

Re: What's your battery system?

PostPosted: Nov 29, 2009 12:06 am
by paoconnell
I use Eneloop rechargeables, but use alkalines as backups.
I also have a bunch of carbide lamps, but treat them as antiques now.

Re: What's your battery system?

PostPosted: Nov 29, 2009 10:50 am
by liketotallyrandom
Marduke wrote:With the BC900 and AA Eneloops, I find 700mA to 1A works well, since the the BC900 tends to be a "hot charger" by using PWM instead of constant current.


I was wondering about that. So how does PWM work to make it a "hotter" charger? Does that mean it uses more than 700 mA, but only for periodic intervals? Does the BC-700 also use PWM? Is there a mathematical way of figuring out how "hot" PWM charging will make a charger vs. constant current?

Re: What's your battery system?

PostPosted: Nov 29, 2009 12:24 pm
by Marduke
IIRC, the BC900 uses a pulsed 1A current (BC700 700mA) on all levels, which tends to be just a bit rougher on some cells vs an equivalant constant current. However, the BC900 is known to actually work little better on older cells for this reason.

Re: What's your battery system?

PostPosted: Nov 30, 2009 3:35 pm
by harrym
paoconnell wrote:I also have a bunch of carbide lamps, but treat them as antiques now.


Hi Pat,

Wanna cut an old buddy a good deal on your old, useless, worthless carbide lamps????? :waving:

Harry M

Re: What's your battery system?

PostPosted: Nov 30, 2009 5:06 pm
by paoconnell
harrym wrote:
paoconnell wrote:I also have a bunch of carbide lamps, but treat them as antiques now.


Hi Pat,

Wanna cut an old buddy a good deal on your old, useless, worthless carbide lamps????? :waving:

Harry M


Heh. They're worth a bit in their collectively useless condition.

When are you moving back to NM?? We always need MDs, especially ones that can do rescues if need be.

Re: What's your battery system?

PostPosted: Dec 13, 2009 11:29 am
by harrym
Okay, I used AA Eneloop NiMH batteries for a week of diving in Cozumel. I was not impressed and I'm still not convinced that I need to put rechargeable batteries in my backup lights.

I ran all of my Eneloops through the break-in mode of my Maha MH-C9000 smart charger in the week before I left for Mexico. I used the batteries in my camera's strobe light and in an 8 AA primary dive light (the Fisheye FIXLED500DX).

The batteries lasted a long time in the strobe, but the dive light reverted to a back-up low-power mode after only two minutes. Every day I cycled the batteries through both the strobe and the dive light, and recharged all batteries every night.

In the low-power mode I had adequate light to get around the cave, but I would not depend on rechargeable batteries for my backup lights.

http://www.scubaboard.com/gallery/showphoto.php/photo/144106

Re: What's your battery system?

PostPosted: Dec 13, 2009 11:57 am
by potholer
Under high load, Eneloops should hold up distinctly better than alkalines - pulling 2.4 Amps into a little LED floodlight I built, I still get 1.18-1.22V/cell on Eneloops, but 1.05-1.1V/cell with fresh Duracells.

Therefore, I'd guess your light isn't drawing a large current, or it'd be worse on alkalines than Eneloops right from the start.

Even at lower draws, to only run for a couple of minutes on high, that sounds like it's dropping to backup mode at ~1.25V/cell. That would mean that on alkalines, it'd generally be doing that when they're a long way from empty, (more like when they're half full) and so sounds like it's a bit oversensitive, or at best, it's designed to drop into backup mode very early to make sure it always has a really long runtime on backup.

It certainly sounds like that particular light might be better off with alkalines, but at the very least, I wouldn't use that light as any kind of indication of how any other light should be expected to perform on Eneloops, since many other lights would behave quite differently.

Re: What's your battery system?

PostPosted: Dec 14, 2009 10:25 am
by werewolf
I use Eneloops and similar hybrids in almost everything. I have a Maha Powerex MH-C204W battery charger, but it won't charge an odd number of batteries, be it one or three. What charger will work with three AA's or AAA's if you have a light that uses three, or one alone, if you have some gadget that uses only one?