back up torch, battery changing

[frisky fraser]

hi folks,
just sitting here wondering,how often do you change the batteries in your back up,even if you've not had occasion to use it at all,or rarely.I've a frogman lenser,and i have used it it on a couple of occasions,once for a full 1 hr dive!!,but it's still as bright as ever!!.I'm a mean git,and it is a led,do these torches just blink out? or do they dim eventually.

Fraser.

[TerryH]

Originally Posted by frisky fraser

hi folks,
just sitting here wondering,how often do you change the batteries in your back up,even if you've not had occasion to use it at all,or rarely.I've a frogman lenser,and i have used it it on a couple of occasions,once for a full 1 hr dive!!,but it's still as bright as ever!!.I'm a mean git,and it is a led,do these torches just blink out? or do they dim eventually.

Fraser.

Although they are meant to run on 1.5 volts they will happily run on 1.2,
so save your worries and buy a set of rechargeable. That way they can
be A1 on every dive

[Martin Owen]

I'm pretty sure LED's either work or don't and they don't dim like a normal bulb, however they need less power than a normal bulb, so will last many times longer.

[Mal Bridgeman]

As the adage goes, if you really need your backup lights you'd pay anything to have one.....so having bought one, it's worth looking after.

The backups I use have a minimum voltage threshold where they recommend changing the batteries .... so I occasionally check the voltages.

Before significant dives ..... like a deep one or a cave .... I would check the voltage in the morning when I check the voltage of my main light. Otherwise I have a strict routine of changing them every so often

HTH
Mal

BTW Rechargables may not provide the voltage decay that you'd like so make sure you are au fait with how they will run out and whether that's good for you.

[Scuby]

I usually carry two torches, so on most dives just carry on using them until they run out. Being LED, that's not very often!

If i'm doing a dive where I *need* a torch (rather than just being nice to be able to see a bit more colour, etc) then i'll check the batteries before the dive, and usually change them for a new set (and then stick the old ones back in after).

David

[nickb]

Originally Posted by TerryH

Although they are meant to run on 1.5 volts they will happily run on 1.2,
so save your worries and buy a set of rechargeable. That way they can
be A1 on every dive

So you drain and charge your backup torch before every dive trip then?

If not, you shouldn't expect it to have much of a charge when you come to use it. Constantly topping-up rechargeable batteries without a full discharge/recharge cycle every so often will screw them eventually.

Don't do this people, it's not a clever idea and a couple of C-cells cost very little.

[DIVE BUDDHA]

a good little back up torch is the uk 40 with the led head very nice and lasts for ages before the batteries need replacing or re-charging

[Scuby]

Originally Posted by nickb

If not, you shouldn't expect it to have much of a charge when you come to use it. Constantly topping-up rechargeable batteries without a full discharge/recharge cycle every so often will screw them eventually.

Depends on the battery chemistry. NiMH (which are by far the most common these days) don't have that problem to any significant extent. I'd suggest that a top-up before every day (or every dive depending on battery life) will be more successful than my method of carrying on using the old non-rechargeable's until they die (as described above).

David

[NotDeadYet]

There are NiMH batteries which are designed for standby use and are guaranteed not to lose more than a few % of a full charge, with quite long periods unused on standby.

I use Vapex 2900mAH NiMH batteries in my handheld 10W HID which I use as a backup (looks like a fat Scout), as long as you remember to top it off before a dive then they're fine, they'll do 3hrs on a full charge.

Originally Posted by Mal Bridgeman

As the adage goes, if you really need your backup lights you'd pay anything to have one.....so having bought one, it's worth looking after.

I've probably told this story before but here goes again...

I was diving a cave in France with a new torch with a NiMH battery a few years ago now. No warning, light goes out on the way out (but a fair way inside and at depth). Fine, I think, I'll go to my backup... reach for it, nothing there but the clip... So I'll go to the other one, where's the problem? Switch it on, shitty yellow/brown light that barely made any headway. I'd thought about changing the batteries but then thought, bollocks to it, it's only a backup, I'm not going to need it... doh! I'd also been using the torch about the house, on camping trips, etc., so the batteries were well used as well... second doh! There wasn't much life left in it, that was easy to see, and I knew my stage bottles that I needed to pick up were not clipped to the line but shoved out the way (combo of the line running midwater and negative steel stages that would have pulled the line out of place) and a fair way away so without the light there was no way I'd have enough backgas to deco and exit, that's the third doh! The fourth doh! was the realisation that I was solo, 1/2km inside a cave with no lights and no way to find the gas that I needed... I figured I'd get as far as I could on the now flickery, dim light and hope that either I'd reach the stages, meet someone else on the way in or have some sort of miracle. Surprisingly, the torch lasted as far as the general area where I'd dropped the stages. I got a bit further, thought I could just see the glint of a 1st stage in the distance and went flat out (there really was f**k all left of the torch by this point). As I reached the stages I saw a green shape on the floor of the cave, an old UK SL4. It seemed too good to be true but it actually worked as my Pelican spluttered out completely. I got the stages and got out as fast as I could. Someone was smiling on me that day. First thing I did after getting all the kit off was walk to the village, buy a bottle of wine and neck it in about 15min.

[nickb]

Originally Posted by Scuby

Depends on the battery chemistry. NiMH (which are by far the most common these days) don't have that problem to any significant extent. I'd suggest that a top-up before every day (or every dive depending on battery life) will be more successful than my method of carrying on using the old non-rechargeable's until they die (as described above).

They still give up the ghost in the end if they're charged on a regular basis. However that's not really the issue AFAIC.

The whole point of a backup torch is that you DON'T use it every dive. Therefore the batteries shouldn't drain. Decent alkaline batteries can last 5 years or more so my backup stays attached to my harness and I check the voltage with a Megger every few months and sling them when they hit their 'sell by' date.

If you remove your backup to charge it before every dive trip, sooner or later you'll forget to take it with you and Mr Sod will inevitably invoke his law.