Usually if we used a VHF FM Transceiver, the problem always at battery because the battery have life cycles, so, if the battery is dead, we need to replace with new one. But the problem is, the battery is expensive.
Open the battery from handset. You'll see Handset contact pads and Charge Pads at battery body. Be careful with this two contact pads, DO NOT SHORT IT !!!
Opened battery cover carefully, all cover sides have small glue, so please open it with patient, used small minus screwdriver. If the cover already open, take out the battery pack with carefully and leave cables and any part inside.
Before you take out the battery pack, it better if you make the circuit drawing first, this is to make sure you not forget and not wrong in replace the new battery. This is important. See the picture carefully for the connections. The battery is in series.
Find AAA recharge Battery with current more than 700mAH, bigger is better because will increase handset stanby and talk times. In this project, i used Sony Ni-MH 2300mAH battery. We need 8 pcs ( @1.2V x 8 = 9.6V. This is handset operated voltage, we can the specification at battery cover. Please read it first.
Make battery connection in series, refer to the schematics for this step. Used small piece of cable for his connections. before you can make solder at battery, used cutter to scratch the battery to make sure the solder and wire can fit at battery. make sure all connection stick with strong at battery point.