PDA

View Full Version : Rechargable NiMH Batteries with LED Torches?



davieeeee
11-01-2007, 09:28
Is it possible? Does it last as long? Is it worth the effort? :dunno:
In particular I am talking about using off the shelf rechargables on the Princeton Shockwave LED but it would be good to get information on all torches in general, so that other people can benefit from this thread.

auvie
11-01-2007, 10:31
While I don't have a LED dive torch, I use NiMH 15-minute rechargeables in my digital camera and they last pretty long (a lot better than alkalines)... and a digital camera sucks back a lot more juice than LED lights. LEDs, in comparison to other lights, do not drain a lot of power, and they have a pretty constant rate of drainage. I would expect NiMH to outperform the standard alkalines you might normally use.

mitsuguy
11-01-2007, 10:35
although I haven't done any long term testing, new battery vs new battery, the NiMH batteries have equivalent out put to an alkaline battery... The batteries I've used are the Energizer NiMH ones you can buy almost anywhere... I do not know how long they will last however in comparison - it's typically "a long time" and the good thing about rechargeables is that you can buy two or three sets, and rotate charging them...

CompuDude
11-01-2007, 12:13
Energizers are junk. 2200 mah? Go to Thomas Distributing (http://www.thomasdistributing.com) for the best rechargeables.

6000 mah C-cells. Nothing beats them. They're not cheap, though... I would do it for environmental reasons vs. price reasons with an LED flashlight, since battery life is already so long. Bear in mind most NiMH batteries don't maintain charges well, so be sure to charge your batteries at least once a month, whether you use it or not. I've been using them for a couple of years in my UK Light Cannon HID and have been very pleased with the results... I get about 4 hours of burn time out of a freshly-charged set.

davieeeee
11-01-2007, 18:55
what exactly oes the 'mah' refer too? I am guesing it means the energy capacity of the battery. If so, is there any disadvantage in having a higher mah battery?

davieeeee
11-01-2007, 18:59
also is nimh still the way to go?
I noticed a few other types of rechargables on that site

Puffer Fish
11-01-2007, 19:05
Energizers are junk. 2200 mah? Go to Thomas Distributing (http://www.thomasdistributing.com) for the best rechargeables.

6000 mah C-cells. Nothing beats them. They're not cheap, though... I would do it for environmental reasons vs. price reasons with an LED flashlight, since battery life is already so long. Bear in mind most NiMH batteries don't maintain charges well, so be sure to charge your batteries at least once a month, whether you use it or not. I've been using them for a couple of years in my UK Light Cannon HID and have been very pleased with the results... I get about 4 hours of burn time out of a freshly-charged set.
I believe that is the second time today you have beat me with an excellent response...

Only real issue I know of is that Nimh's loose their power over time fairly fast.. there are some new ones that are much better at this, but not with the same power.. I love the Sanyo batteries from them....as they will hold a charge longer, and are of reasonable strength.

Puffer Fish
11-01-2007, 19:14
also is nimh still the way to go?
I noticed a few other types of rechargables on that site
They have the best power, but there are several other types, with less power (longer shelf life) or in non-standard sizes.

I bought some of the 2,900 AA's, and made the mistake of dropping one...which meant I had three good ones and one bad... for a unit that needed 4 good ones...

davieeeee
11-01-2007, 21:03
And what about the chargers themselves? Are there any differences in charging quality or are they all the same? (Obviously exluding the fact that some have more slots that others and some are rapid charging)

Puffer Fish
11-01-2007, 21:09
And what about the chargers themselves? Are there any differences in charging quality or are they all the same? (Obviously exluding the fact that some have more slots that others and some are rapid charging)
Hard to tell, because of the junk they promise.. I have several of the ones sold on thomas...they seem to work well, but perhaps the cheaper versions would work as well. I should have gotten a 8 battery hold though, as I need two of the 4..

There is also some that charge two at a time, some that do four at a time and some that are individual charges...Individual chargers are more likely to spot a bad battery...and the more at one time, the less likely that is.

davieeeee
11-01-2007, 21:59
Thanks for hte information guys, it was really helpful. I now know what to look for in rechargables... The only question now is.. will it be worth it? The reason I am still not quite sure if I should get rechargables is that the PrincetonTec website states that the Showave LED has a burn time of 20 hours on Low Setting.. Now Im not a big night diver, in fact I think that I will probably log less than 15 night dives in a year... so quite possibly, it might take me years to make up for the money I spend on rechargables... decisions decisions.!

mitsuguy
11-01-2007, 22:50
pretty standard energizer rechargeable D cell batteries are $4 each for the most part...that light takes 8 batteries, so, $32...

a single set of 8 c cell batteries from energizer or duracell is like $10-$12 I think I would go ahead and do rechargeables, just to make sure I always had a fresh charge, instead of having to worry every time I went diving how much power was left in the batteries...

davieeeee
11-01-2007, 22:53
Hey thats a good point... With disposables, i would always be wasting it near the end of its life, as I wont really know how much energy is left in it, so could possibly needlessly replacing them... Whereas with rechargables I would alway just have them charged fully...

CompuDude
11-02-2007, 04:12
Hey thats a good point... With disposables, i would always be wasting it near the end of its life, as I wont really know how much energy is left in it, so could possibly needlessly replacing them... Whereas with rechargables I would alway just have them charged fully...

That's how I look at it. I got tired to trying to remember how long each light had been on, and trying to decide if I should risk it lasting or dump them early for safety. I'm sure I have tossed quite a few perfectly good batteries as a result.

I bought a couple of set of NiMH batteries, charge them before each trip, and have the satisfaction of always knowing I have fresh batteries before I go in.

Navy OnStar
11-06-2007, 08:01
what exactly oes the 'mah' refer too? I am guesing it means the energy capacity of the battery. If so, is there any disadvantage in having a higher mah battery?

mah = Milli-amp-hours

a 2200mah battery will provide: 2200milli-amps for 1 hour
1100milli-amps for 2 hours
22milli-amps for 100 hours
and so on

Just divide the rating by the power draw of the LED/light and you will get burn time

2 2200mah batteries in series will provide 2200 milli-amps for 1 hour but at twice the voltage

2 2200mah batteries in parallel will provide 2200 milli-amps for 2 hours but at the original voltage

Hope this helps

Oh, and the disadvantage to higher power is usually higher cost.

OnStar

davieeeee
11-06-2007, 08:44
now THAT i never knew! Excellent info Navy!

Navy OnStar
11-06-2007, 09:54
Your welcome!!

Unfortunatley, that exhausts the full extent of my limited knowledge. I will no longer be able to provide any useful info unless I forget what I just wrote to make room for something new!

Navy OnStar
11-06-2007, 09:57
Oh, also a 2200mah battery can supply more than 2200milli-amps

say 4400ma but only for 30 mins (but only to a certain extent before you damage the battery due to high heat)

OnStar

Ow....My Brain hurts!

Tableleg
11-06-2007, 16:19
Won't the internal resistance of the battery prevent it from getting a current that high? I've been impressed with the fact that there are even 2.7AH AA's, but I don't think it's possible for a AA to output that much.

Navy OnStar
11-06-2007, 17:43
Most (if not all) AA's can't discharge that fast. The internal resistance is what causes the heat which damages the battery. The faster you try to discharge it the hotter it gets. For aplications that require more current (milli-amps) they put batteries in Parallel, so each battery provides some of the current.
I really wasn't thinking of Just AA's when I posted. We Use 17Amp-hour batteries in our helicopters but use upwards of 30 amps to start the engine as an example.

Good catch! :smiley20:

OnStar

Tableleg
11-06-2007, 21:08
The internal resistance is what causes the heat which damages the battery. This can also lead to a run-away issue because as the heat increases, so does the resistance. :smiley2:

We Use 17Amp-hour batteries in our helicopters but use upwards of 30 amps to start the engine as an example. But that's just when they start up. Do you know what kind of batteries they are? Is this a people helicopter (and if so, how many batteries make up the bank? Surley it's not just one) or a model helicopter with just a big honk'in battery? :smiley1:

Navy OnStar
11-07-2007, 07:58
We Use 17Amp-hour batteries in our helicopters but use upwards of 30 amps to start the engine as an example. But that's just when they start up. Do you know what kind of batteries they are? Is this a people helicopter (and if so, how many batteries make up the bank? Surley it's not just one) or a model helicopter with just a big honk'in battery? :smiley1:[/quote]

One single battery on a people helicopter. We used to use NiMH batteries but had thermal run away issues along with other issues. We now use a SLAB (sealed lead acid battery) which actualy provides more power for the same rating on start. We have fewer overtemp starts using a 17ah SLAB vs. a 17ah NiHM

Puffer Fish
11-07-2007, 09:21
We Use 17Amp-hour batteries in our helicopters but use upwards of 30 amps to start the engine as an example. But that's just when they start up. Do you know what kind of batteries they are? Is this a people helicopter (and if so, how many batteries make up the bank? Surley it's not just one) or a model helicopter with just a big honk'in battery? :smiley1:

One single battery on a people helicopter. We used to use NiMH batteries but had thermal run away issues along with other issues. We now use a SLAB (sealed lead acid battery) which actualy provides more power for the same rating on start. We have fewer overtemp starts using a 17ah SLAB vs. a 17ah NiHM[/quote]


An excellent use for a SLAB.. and a sucky one for a NiHM. I like NiHM's, but boy do they have issues.. just drop one on a hard floor - if they land wrong they will not work. There is the "filiment" issue over time...a very touchy battery in the high performance end of them.