The larger the number the longer the battery will last.
1500mAh
If it will physically fit in the space, then yes, the 2700 mAh battery should work fine.
1500mAh standard Lithium Ion rechargeable battery.
It means it has more power.If it fits in your phone it should work.But look where the battery goes it might say there is a may battery you can put in it.
The Samsung SCH-W750 Li Ion battery can last up to 180 hours on standby and has 7 hours of talk time. When shipped it came with a 1500mAh model battery.
If you need a battery then there is nothing that can replace it.
Depends on the drain. if the drain is 1500mAh it'll laso one hour before the voltage drops too low. If the drain is 500 mAh it'll last 3 hours. 150mAh, 10 hours 3000mAh, 0.5 hours.
i would recommend a smart charger for your batteries
if the battery gets weak and useless, then you have to replace it...
how to replace battery
how to replace a mitsubishi endeavor battery