DIR ? : Re-chargeable batteries in a backup

[King Kong Matt]

My understanding is that you should NOT be using re-chargeable batteries in your backup.

Is this correct, and if so, can someone please explain why? Can't seem to find anything here or on Quest.

Thanks,
Matt

 

[Cave Diver]

That is correct.

The reason is that backup lights are considered essential equipment. In the event that your primary fails and you need a backup it, it needs to work. Rechargeable batteries often discharge at a faster rate, and on subsequent charges, take less than a full charge. They also tend to reach their "failure point" with less warning. i.e. a "regular" battery gradually yellows and dims to warn you it's dying. A rechargeable may just quit once it passes that threshold with little or no warning.

Oh, one more thing. Dont forget about the added hassle of having to take your charger with you on trips. Especially if you need european adapters. And if your light floods and the batteries get ruined, it is easier (and cheaper) to find regular batteries.

I was thinking about going rechargeable myself once, but then I learned better. Hard to beat the reliablity of a 2 or 3 cell alkaline flashlight.

 

[King Kong Matt]

Cave Diver once bubbled...
Rechargeable batteries often discharge at a faster rate, and on subsequent charges, take less than a full charge. They also tend to reach their "failure point" with less warning. i.e. a "regular" battery gradually yellows and dims to warn you it's dying. A rechargeable may just quit once it passes that threshold with little or no warning.

Ok. That makes sense and thanks for that. But, and I know very little about this so put on the idiot filter here, is what you're saying still true of NiMH bats as well? I thought they solved a lot of these problems.

Again, thanks for the answer.

 

[bwerb]

King Kong Matt once bubbled...
put on the idiot filter here

I think I should begin all my posts with the idiot filter in full functional mode...this was a great post...I'm thinking of changing my signature.

 

[Spectre]

My cavern instructor and I had quite a few discussions about this.

NiMH has the problem of a fast discharge. It goes strong until it's done, then blink; it's out.

Now the rechargable alkalines are another story. When presented with the 'no rechargables', I enquired why. I got the 'fast discharge' response. I then questioned the alkaline rechargables; as they don't have the fast discharge.

We tried to test it during class; but we only had about an hour and a half to have the light going; and there was no change in the brightness.

After I got home however, I tested it. After about 3 hours it started to dim, 4 hours it was to dim to notice above the ambient light in the house.

So personally, I believe rechargable alkalines are fine, but of course that's not the exact question your asking...

 

[King Kong Matt]

bwerb once bubbled...


I think I should begin all my posts with the idiot filter in full functional mode...this was a great post...I'm thinking of changing my signature.

I hear ya bwerb...I'm picking up what you're putting down.

I don't get up in the morning without strapping on my idiot filter and dialing back my give-a-rat's-a$$ meter to a little on the negative side...

 

[Cave Diver]

King Kong Matt once bubbled...


Ok. That makes sense and thanks for that. But, and I know very little about this so put on the idiot filter here, is what you're saying still true of NiMH bats as well? I thought they solved a lot of these problems.

Again, thanks for the answer.

Some of the newer battery technology has solved alot of those problems. A lot of HID lights use NiMH batteries, but HID also has a lower discharge rate than an equivalent brightness halogen bulbs. Of course, I'm talking primary lights here when you asked about backup, so I'll get back on topic.

It's my personal opinion, that given the reliabilty of alkaline, and some of the potential pitfalls of rechargeable batteries, that I would hate to turn on a backup light in the case of real need, only to find that the battery has discharged.

Alkalines have a much higher shelf life when not in use than rechargeables. The burn time of an rechargeable often shortens with age, even if the battery is properly mantained. In the long run, rechargeable backup lights might be more $$$ effective, but what is my life worth in the event I really need that light to work.

Perhaps some of the others with more knowledge on current battery technology can chime in with opinions. I'm certainly open to hearing any differing viewpoints.

Good topic KKM

 

[King Kong Matt]

Spectre once bubbled...
So personally, I believe rechargable alkalines are fine, but of course that's not the exact question your asking...

This is all good info. I'm more than content to use non-rechargeables. But, you know, like most (all?) things in DIR, there is a specific reason as to why those guys do the things they do.

The reason posted is certainly a cogent one.

 

[Cave Diver]

Spectre once bubbled...
After I got home however, I tested it. After about 3 hours it started to dim, 4 hours it was to dim to notice above the ambient light in the house.

So personally, I believe rechargable alkalines are fine, but of course that's not the exact question your asking...

The only problem I see in this is that you need to periodically check the burntime on your rechargeables to make sure it's holding.

Traditional alkalines aren't going to vary in burntime much from one new set to another.

Not really a biggie, but it does add one more thing to have to maintain, and it's something that could easily get overlooked. The bad part is that you may realize that you havent done a recent burntime test when it starts to fail and you really really need it.

 

[Cave Diver]

King Kong Matt once bubbled...


This is all good info. I'm more than content to use non-rechargeables. But, you know, like most (all?) things in DIR, there is a specific reason as to why those guys do the things they do.

The reason posted is certainly a cogent one.

Actually, most of the info I stated came from my cave instructor, who was definetly not a DIR tenet. Still made good sense to me tho, and so do most of the DIR things.