My MIT-Racecar can not start with LiPO battery

[ArtlyStyles]

I used to use NiMH and everything works fine. To get more power, however, I replaced the NiMH battery with 4S LiPO. After that, I found that my car had difficulty to start. Please see the video here https://www.youtube.com/watch?v=D1XGa-vANRY I am not sure how to fix it and why I did not have the same problem with NiMH battery. Anyone uses LiPO battery and experienced the same problem?

[EwingKang]

By pure guessing: I heard some clicking noises the moment you throttle your vehicle. Sounds to me the gearbox is having some gear slipping issue? Maybe Lipo is too powerful for your transmission.

[ArtlyStyles]

Thanks. Someone told me I need to "gear down". But not sure what this means and how to do it...

[EwingKang]

@ArtlyStyles I suppose that means you need to either use a gerbox with higher gear ratio, i.e. slower wheel turn with less motor rpm and hense the "gear down".
You can also try to use a stronger gearbox with matel gears, or simple use a less powerful battery, a 3 cell one maybe?