UKC

Just seeing if anyone has any info on this, but I have a petzl iko core battery for my running headlamp which is essentially 3 AAA sized batteries in a block that's rechargeable.

However, this has completely flat sides thus won't fit in headlamps that have a AAA battery compartment with ridges/individual dividers. The same issue with the BD 1800 battery.

Is there something out there that has the shape to fit headlamps with a 'normal' battery compartment? I quite like the idea of one singular battery that is rechargeable than using individual AAA batteries that require a separate charger.

Thanks in advance.

Irritating that it cannot be used instead of 3 x AAA in other headtorches, but I think that the Petzl Core comprises a single rectangular Li-ion cell (3.6V, 1250mAh), so it would not be possible to produce it in the shape of 3 AAAs side by side. Don't know of anything that is that shape.

What about the BD1500? It’s the drop in replacement for 3xAAA in BD’s “dual fuel” head torches. 

Unfortunately that's the same shape as the BD 1800 battery, which all suffer the same problem as the iko core in that the sides are completely flat.

I'm starting to wonder if it's just easier to modify the battery compartment instead.

I've done this to use core battery (they're very good) in a 3*AAA super cheapo head torch (one torch from a pair of buy 2 head torches for 10.99 on Amazon), even cut a little hole in the battery compartment so I can plug in the battery without having to open it (that does reduce water resistance). I found that trimming out some plastic in the battery box to accommodate the core wasn't too difficult, don't do anything silly and cut your hand accidentally though

Not familiar with the BD1500, I'm afraid.

You can get NiMH AAA cells, tagged for soldering  or untagged.  They are good enough to use in battery packs for dependable VHF/UHF radios so I wonder if this might be the answer.  Your charger would have to be suitable for NiMH. 

Hope I have not misunderstood the OP.  Cells available on well known auction sites.

On occasion I have removed ridges in battery pack casings to fit different cells. (Filing or cutting with craft knife)

I used NiMH cells for years in my old Petzl headtorch, and still do for winter dog walking duty. The problem with them is that they don't retain their charge well, and I would imagine on a longer walk/trip the OP doesn't want to take a separate charger with them. The Li-ion Petzl Core is much more convenient.

Yes, they aren't ideal and they do self discharge over time but the advantage is that they are amenable to being topped up whenever possible and aren't damaged by over discharge.  If you adopt a Lithium based solution you need charge/over discharge protection.

Perhaps a flat but thin enough Li-po cell of suitable size might fit, with a tiny protection board.

You've just described the Petzl core battery that the OP is trying to fit in! 😂

LED Lenser do a version of the same thing too: https://ledlenser.co.uk/collections/rechargeable-battery/products/battery-p...

As do Silva.

https://silvasweden.uk/collections/headlamp-batteries/products/hybrid-batte...

Well, in principle, but I understood that something the size of the Petzl Core would not fit so therefore a thinner Lipo cell might fit in the space between the ridges, suitably protected.

880mAH as in the Lenser offering is not big, only a bit more than batteries in disposable vapes at 550maH, so perhaps something wide and flat could achieve 880maH or more in the spaceshape.