mxxc

Close enough, I actually glued 2 4x AAA battery holders together. The conductor pieces were made from a soda can. I will update some instructions later.

I got a 42099 recently and was kind of disappointed by the slow speed of the 6x AA nimh batteries (7.2V), so I made this 8x AAA battery box (9.6V, or 12V if you use alkaline). The speed boost was tremendous. The fully charged 8x nimh batteries could reach almost 11.5V, but the voltage drops quickly. In theory it should be stabilized at 9.6V. 6x AA battery box. The downside is 8x AAA will have less playtime than 6x AA. I don't know exactly how long you will get from this setup. I took the offroader to a park over the weekend and played 30 minutes without issue.