Hey Shin, remember I said "I have a Hummer like that somewhere" I found it!
It's been in a box under my bed for about 6 or 7 years, It runs on two N size (2/3 length AAA) size batteries, this is probably why it went into storage, I have a cunning plan.....
Here I have it running on a 50mAh Picooz LiPo,
I have a couple of 420mAh cells that I found are two heavy for upgrading my S026 chinook, but they are the perfect size it fit the Hummer, I'll post a video when done.
Oh, I have two of these Hummers' the other one has a PCB fault, steering and transmision are still good, I'm gonna upgade with a fully proportional 27Mhz Rx, standard size is the same as the stock on/off PCB so a mini will easily fit. I'll also use a couple of constant rotation mod servo PCB, one for the steering coil and the second as a speed controller for the rear wheels.
For power it will have two 150mAh LiPo regulated down to 5V at 40% more power it should be really speedy.