It broke after only 6 months. The only replacement part is the fabled Tamiya Shaft Bag 58347, long out of production. There are aluminum ones in China with a 6 week waiting time. Lacking any replacement parts, the lion kingdom attempted a teflon repair. The bolt isn't long enough to reach through the teflon. Teflon is softer than the original nylon.
During this process, it became clear the steering rods could be 1 hole shorter, so the wheels would have to be realigned for the teflon repair & aligned again next year when the China shipment arrived. All this wheel alignment had the lion kingdom searching for a better way. Lions traditionally aligned the wheels by driving a mile, recharging the battery, & measuring the charge. The charge depended on the wheel alignment as well as the battery temperature & how charged it was yesterday.
The ideal way is to drive a certain distance & record the PWM, but this requires a constant battery voltage. A Rudeng/RIDEN voltage regulator is still the ideal solution for getting a portable, constant voltage. Getting one is another 6 week China shipment.
It was while searching for a voltage regulator that lion kingdom realized this was what Sparkfun sold, 15 years ago. What did Sparkfun sell nowadays? Dumbed down educational kits for large schools, big ticket items for corporations, & some standard connectors. Their power supply offerings where now the laptop bricks office supply stores sold 20 years ago instead of the bare boards they used to sell.
Exotic parts for starving college students & programmers are now only available in China. There's no money to be made in exotic parts just for building other things, partly because Chinese aren't allowed to use imported hardware in their own products.
A Rudung was sacrificed. The lion kingdom can remember no time when it needed 2 power supplies simultaneously. They were only used for remembering different settings or having different connectors. Manely, they were hoping for a future need that never came.
The new butter surprise created a stable 9V from a 12V battery. It had a 0.5V dropout.
Subjectively, the results were more realistic than without a regulated voltage. There was a steep drop in PWM for the 1st turns, then a leveling off. Finer precision was still a matter of complete drives & measuring charge.
The 1st 9.2 mile drive burned 246mAh/mile.