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I've been wondering why the NiMH gumsticks available today got stuck at 1450 mAh. The manufacturers of portable gear try to do miracles to extend play times and at the same time the capacity of the cells powering them has remained unchanged for several years.
I mean, the gumstick has exactly the same volume as an AA cell. Given that the volumetric density should be the same for all NiMH cells there should have been gumsticks with over 2000 mAh capacity by now. This would have prolonged batter life with about 1/3 without the need of 2.5 mW per chanel headamps.

 

[leon]

I'm under the impression that it's easier to increase capacity/density on cylindrical batteries (AA, AAA...) and not so easy on prismatic batteries (rectangular boxes). AFAIK this applies to both Ni-MH and Li ion.

And there's of course another reason that's always going to be valid to some extent: it's cheaper for the manufacturer this way, and 1450mAh hasn't become unviable as technology advanced (and allow higher capacity). Having all the power you want is also not such an urgent issue as it is for other products (digital cameras come to mind). In a nutshell - cost.

And I suspect portable audio is generally a low yield business.

 

[Braver]

I suspect the market for gumsticks is too small to warrant an investment to researching higher capacity. only the top-of-the-line portable audio equipment use them, while there are countless applications for AA batteries. hardly any, if any, third-party chargers support the format.

then again...why don't they just 'squash' a 2000 mAh NiMH AA in to a gumstick?

perhaps because they require special chargers, and they haven't been able to make those chargers small enoug to fit in a portable CD or MD player? or the batteries, or the charging-circuit gets too hot for a closed environmnet (so they need vents)?

 

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Interesting thoughts Leon and Braver.
As I see it the technology is there. There are 2100 mAh AAs and this figure is likely to increase still. The volume of a gumstick is exactly the same so it's just to rework the geometry of the electrodes-shouldn't be impossible. It is true that the market for gumsticks is much smaller than AA. To my knowledge there are only 3 companies making them Sanyo, GP and Panasonic. The rest stock from them.
It would have been better to increase the capacity of the cells instead to cripple the players in order to give them 2 days battery life.