HM70R Compatible Batteries

[jwtbids]

Hiya, just wondering if anyone knows the specification of battery needed for compatibility with an HM70R?
I know the Fenix-supplied ones are protected, button-top 21700 cells - I have heard that they must be button top, but do any spare batteries also have to be protected (i.e. with a longer body)? Will an unprotected button-top 21700 work without issue?

Many thanks!

 

[Cantclimbtom]

Unprotected button top would work and theoretically last slightly longer on a charge (protection circuit causes a slight voltage drop), but if you ever totally run the battery down (maybe left on accidentally), that battery is bricked

 

[hoehlenforscher]

I have an adapter with mine lets me run 18650s in it. Just a plastic tube with a positive terminal and an internal spring.

 

[Fulk]

For what it's worth, some time ago I bought a 'Keep Power' 21700/5000 mAh battery for my HM70R from 'Action Stash'. It says on it 'Protected Li-ion Rechargeable Battery'. It seems to be just as good as the Fenix batteries, at about half the price.