The lowest cost way would of course be to add a third battery and see how it goes. Adding a third battery will overvolt the motor and controller and may cause them to burn out though so it is the riskiest option. Many of our customers have done this only to have their controller or motor burn out in a day or two.
We have several kits available to modify the Razor Dune Buggy go kart to run on 24 Volt 500 Watts, and also to run on 36 Volts and 48 Volts.
Here is a link to these kits:
I've been searching all over for the best way to increase the speed / torque of my kids Razor Dune Buggy.
We've been using it since November of 2016 and last week the buggy would only click after a full charge. I took off the back housing and checked each battery, they are only registering 7v each instead of the necessary 12v.
I decided since I'm going to have to buy some new batteries anyway, I might as well jump on the 36v train.
Anyway, after reading around all sorts of forums, I'm still as lost as ever on what all I need to replace.
Here are the answers that I have found so far: