Rechargeable batteries?

Kim · Jul 7, 2005

I recently watched the DIR 3 DVD with George explaining some of the simple stuff about backplates and rigs. When he was talking about small backup lights - the kind that use C-cells etc - he said not to use rechargeable ones for such lights. As there was no further explanation given as to why I was wondering what the reason was.

jonnythan · Jul 7, 2005

Rechargeables require regular maintenance because they lose their charge relatively rapidly. IE you'd need to charge them before practically every dive.

Alkaline batteries have a long shelf life, require no maintenance, and have more predictable output.

Kim · Jul 7, 2005

Thanks Jonny. I'm asking the question as I will soon be in possession of a UK light cannon. I know that they do a rechargeable pack for it (and have read some threads about that), but was just wondering which way to go with the battery thing.

jonnythan · Jul 7, 2005

I'm pretty sure the UK rechargeable pack is NiCad, so you might want to consider just getting some NiMH C-cells instead. Just a thought.

In any case, for a primary light, go with rechargeables. As long as you keep them charged whenever you need them it's no big deal.. but it would suck if you'reunder a shipping channel or something, then take out your backup light and realize it's been a few dives since you've touched the thing or charged the batteries and you don't get enough burn time to get you back to open water..

Kim · Jul 7, 2005

jonnythan:
then take out your backup light and realize it's been a few dives since you've touched the thing or charged the batteries and you don't get enough burn time to get you back to open water..

Ah ha.....there's the real reason! It makes sense......got it! Thanks.

HarryH97 · Jul 8, 2005

Kim,
It has to do with the discharge curve of rechargeable batteries vs alkaline. The akaline has a gradual declining voltage toward the end whereas the rechargeable has a rapid drop in voltage toward the end. Since the backup MUST function, seeing the light getting progressively dimmer is preferred over the light cutting out on you.
Sincerely,
H2

jagfish · Jul 8, 2005

A light Cannon...

Just a thought...
You should be able to get a used 10W canister light for the same cash...(I think)

Kim · Jul 8, 2005

HarryH97:
Kim,
It has to do with the discharge curve of rechargeable batteries vs alkaline. The akaline has a gradual declining voltage toward the end whereas the rechargeable has a rapid drop in voltage toward the end. Since the backup MUST function, seeing the light getting progressively dimmer is preferred over the light cutting out on you.
Sincerely,
H2

Yes....that was my first thought actually, that it might be that sort of reason. Still, rather than guessing I thought I'd ask. I'll be using my UK SL6 as primary backup from now - so I'll keep the Duracells in that.
What Jonnythan said about NiCaD and NiMH is also true. I'm considering going with rechargeable 4000 mAh "C" cells for the light cannon. They seem to be the most powerful that I can find looking around. I'll have to check what's available in Japan.

Kim · Jul 8, 2005

jagfish:
A light Cannon...

Just a thought...
You should be able to get a used 10W canister light for the same cash...(I think)

I doubt it....I won this one in Snowbears' competition!

jagfish · Jul 8, 2005

LOL!

I forgot all about that...

Rechargeable batteries?

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