depends on the condition of the spare battery. why do you need an extra battery anyways?/
i used my BB pretty heavily with work emails and personal txt/pins and it still lasts me a full day (if i remove the phone from the charger the morning of use)
if your battery doesnt last you a day you need to look into a new battery
there are also a couple different batteries i have seen. some are 900mah, some are 1000mah, the one i have is 1100mahs
they also have an extended 1500-1600mah but it bulges out and you require a new back cover. it also makes the phone look ugly. pointless in owning a nice small footprint phone if you have to add a fat *** on the back of it
Yeahh you can leave it on, I recommend that actually.
Charge overnight, the battery types in these 8330's love being charged! Do a battery pull once a day also, that will help with the performance of your device.
Hmm as blackCRX stated, there really isn't a huge need for a spare battery unless you are doing something extremely heavy on your battery. If I had an extra battery I would rotate them out so they both get used...therefore one doesnt loss its "battery life" by not being used!
