I have no idea what brand name 充電池 you use... but you have to know that... some 充電池 need their OWN charger to charge will be better... such as Sanyo, GP, etc...
And also, if you also charge for a long time... the battery life also will be short... and you MUST need to aware that... if you use 850mAH battery... "maybe" some of the equipment cannot be use...
Good Luck!!
** I suggest you to buy Sanyo... 2200 / 2500 mAh ...