Your said charger is great, i use that myself, sadly it doesnt charge until 4.3v, like the samsung battery here you asked about. If i were to suggest battery for your said flashlight, i would go for this
SKU 1141104 ... you can send a ticket and ask if it fits perfectly, id assume it will fit as geek tried it with a battery which has the same battery length of my suggested battery.
Btw, this is the battery geek tested, fits great as he said and has very pretty decent review too, try checking this one out,
SKU 1143802 ...
Edited on 9/19/2013 at 7:40 AM. Reason: