has anyone seen this with headlamp batteries?

[Mike M]

I’m not sure if this is a feature of the lamp (BD Spot) or an oddity?  I check my batteries before each and every trip, I’ll very often have two batteries that register full or nearly full and one that is about dead.  This is with a headlamp that has seen some use.

I pitch the dead battery and replace it with a new one and keep the two fully charged ones in.  I own 3-4 BD Spots (few different generations) and I think (not a 100% sure) it happens with all of them.

Batteries are always lithium.

I’m not adverse to it, as I would probably replace all three batteries if they were half charged, this way I’m often only replacing one.

Odd

 

 

[Jerry Adams]

“they” say to have all the batteries matched – same charge

if you have 2 half charged batteries and add a third fully charged battery, you are not following recommendation

I don’t know how much different they have to be to be a problem.  You could cause batteries to leak maybe?

I’ve been using a Black Diamond Iota.  Built in rechargeable lithium.  I make sure it’s fully charged before each trip.  I also have a USB battery to charge up my phone which I could use to recharge the Iota, like if I had to do an unexpected night hike that discharged it.

[Mike M]

well the way it happens I do have all three the same when I head out- all full

not sure why one battery after use is near dead and two are fully charged- I thought possibly it might be a feature, draining one battery at a time?

[Jerry Adams]

oh, I see what you’re saying, weird, maybe that’s what it does

[Michael Sirofchuck]

Maybe don’t store it with the batteries installed?  My headlamp and batteries are in a small CF stuff sack.  I don’t put the batteries in until darkness is approaching.

[David Thomas]

I’m theorizing here, as I am prone to do, that MichaelS may be right and if the device pulls from a single battery to power minimal circuitry to look for you to press the “on” button, then a month or two later, that particular battery could be a lot more drained.

If you aren’t throwing an old-fashioned physical switch, but rather hitting a soft button (that does lots of things depending on if you press it, press and hold, press it 3 times, etc), then some circuitry must be energized to notice you do that.

I had issues with an early SteriPen that drained the batteries between trips.  Simply removing the batteries (or any one of them) eliminated that problem.

[Edward John M]

Try swapping the position of the batteries in the casing and see what happens.

[Mike M]

I did a trip last weekend and just broke out the batteries, the middle was near dead, the two outers near full- it was an outer one last time for sure that was near dead

someone suggested that the tester I have won’t be accurate for lithium AAA’s (only alkaline) and that while the tester is showing nearly full they might not be

going to look for another tester

[Mike M]

^ I’ll try storing it w/o batteries and see what happens

[Eugene Hollingsworth]

What Edward said, “swap the batteries to different positions.” Be sure to label and log what you are doing.  My guess is you have a weak self-discharging battery or a faulty headlamp.

The only time any “feature” of discharging one battery would be that all are in parallel, otherwise if in series that would be a potentially dangerous situation with LiOn (that’s what you meant by lithium, right?) Just lithium isn’t going to be dangerous, but that’s still not right.

Wait-not that “parallel” config doesn’t make sense either unless the circuitry actually isolated each battery from the other and who would design something like that?

[Jerry Adams]

I remember some device that has two batteries, but if you put just one in, it starts working

So the batteries are isolated from each other

I don’t know if it draws power off just one first, or draws power in a balanced fashion

[Mike M]

the batteries are primary lithium AAA, non-rechargeable

the “bad” battery is always tossed, so shouldn’t be a weak one left

I’m going to remove the batteries and before my next trip replace with three fresh lithium AAA’s and see if it happens again

[R]

Lithium batteries discharge with a much flatter voltage curve than alkaline.  When a lithium cell is half drained, it still looks full to a tester designed for alkaline voltages.  And when it looks half drained to the tester, it’s probably dead.

Your process of discarding the dead battery and keeping the others ensures that all three cells differ in capacity by several hours, so they’ll die one at a time.  Remember, your alkaline tester is telling you the half drained cells are still full.

Rechargeable batteries avoid this problem, and spare the waste stream.  This is my solution and I recommend it to everyone :)

Spec’s, for reference – look at the volt/hr curves:

Energizer AAA lithium: https://data.energizer.com/pdfs/l92.pdf

Energizer AAA alkaline: https://data.energizer.com/pdfs/e92-1119.pdf

[Eugene Hollingsworth]

That’s a really good point, Rene.

[Mike M]

I have a battery outfit in town, might be worth bringing in my “full” batteries and have them properly tested; as Rene pointed out they may be half dead (or worse?)

[Eric B]

Just buy an inexpensive multimeter – then you can test batteries of any chemistry and gain useful data.

[Mike W]

Don’t buy a cheap battery tester!

I couple of years ago I finally bought  a high end “load tester” for batteries.  Seemed crazy expensive (… but my wife bought it for me for my birthday… so less painful for me), but it’s been incredible!

https://www.ztsinc.com/mbt1.html

It tests all kinds of batteries (under load), so it has been great for me as I have many different types of rechargeable and disposable batteries to test.

I always test my 18650’s, CR123’s, AA Lithiums and Alkalines and button cells before heading off on a trip.  I don’t like to depend on luck when it comes to my electronics and so this device has taken out the guess-work.

The first thing I did was test all of my Steripen batteries (CR123 disposables) because they always seemed to test “full” with my cheap tester.  Turns out I tossed 75% of them as most of them registered very low under load.

As a side comment… I got rid of my BD Spot and bought a Zebralight H53w AA Headlamp.  It uses one AA lithium (or any other AA battery type) and has been incredible.  I always hated buying AAA batteries (and carrying 3 spares).   I just carry one extra AA lithium and that’s it.  I also like the fact that it’s actually regulated and steps down when the batteries get low (doesn’t slowly dim like the Spot).   The beam quality is also far better than the Spot.

[Mike M]

^ mine is the ZTS Mini, but it shows AA/AAA as 1.5v alkaline- I’ve been using that to measure the primary AAA’s, but not sure if they measure the same?

[Mike W]

Lithium batteries have a higher voltage than alkaline, so they won’t measure accurately.

My tester (ZTS MBT-1) has a separate tester that does all alkaline batteries and a a tester for AAA lithium and another for AA lithium, which would suggest they are all different.

[Roger Caffin]

I am not aware of any difference in voltage between AA and AAA.
It may be that the cells have different physical sizes?

Added: I have checked the technical data sheets I have, and lithium AA and AAA are reported to have the same voltage and same chemistry.

Cheers

[Mike M]

Ahhh- yeah mine doesn’t have the extra spots for testing lithium AA/AAA’s (just Alkalines)

 

appears I might need to upgrade my tester

[Mike W]

Sorry for the confusion Roger, it was late and I wasn’t being clear.

You are correct that all AA and AAA are 1.5 V cells.  What I was referring to was that 1.5 V Lithium batteries have a different discharge curve than Alkaline batteries and output 1.5 V for longer than Alkaline batteries.  This makes battery testers for Alkaline batteries unreliable for testing Lithium batteries.  A lithium battery that is at 75% will read 100% on a tester made for Alkaline batteries.  (see chart below)

Another feature of Lithium batteries is that they hold their voltage better under load, so the voltage will remain at 1.5 V while under load while the Alkaline cells will start to drop in voltage fairly quickly.

[Derek M.]

This kind of thread is a reminder to me of why I completely switched to USB rechargeable headlamps over 5 years ago. I’ve never looked back even for a second.

I must say I’m kind of shocked with how many non-rechargeable headlamps there still are on the market, but that is a topic for another thread.

I hope the OP can get this battery drain problem sorted, but if not, I’d strongly suggest seeking a rechargeable option as a replacement.

[Roger Caffin]

It is interesting to compare lithiums and alkalines.

* The alkalines die around 0 C because they are water-based; the lithiums are good to -40 C iirc. Think about this in the snow.

* The alkalines have only a fraction of the capacity of the lithiums. The AA lithiums are rated at 3000 mAhr to 1.0 V; most alkaline AAs don’t even get a rating. so you would need to carry a lot more alkalines than lithiums.

* The alkalines are noticeably heavier than the lithiums on an individual basis too.

* The alkalines are cheaper than the lithiums up front, but when you factor in the capacity it turns out that the lithiums are much cheaper than the alkalines.

All of which leaves me wondering why anyone buys the alkalines at all. I did notice that when the lithiums came out, the price of the alkalines plummeted under the competition. I won’t buy any ALKALINES these days.

Cheers
Edited to correct a glaring typo – thanks Mike M!

[Mike M]

Roger I think you meant to say you won’t be buying anymore alkalines.

Got an email from ZTS, they confirmed the alkaline test spot will always read the lithium primaries high (until they are almost dead)

Soooooo I just ordered the bigger tester, now I’ve got a small one and a big one :)

[Author]

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