The club has a number of Digitrax UT4R and UTRD throttles. These are radio throttles require 9V batteries to power the throttle while tethered. These 9V batteries have become increasingly expensive and tend to not last very long with our long operating sessions.

Rechargeable variations of 9V batteries exits most interestingly a variation that has a built in USB changer. More information available here.

There is however a plentiful free source of Lithium Iron batteries inside of disposable vape devices you just need to do a little work to extract them. So we collected a few and extracted the batteries. There 3.7V cells were tested and the good ones measuring more than 3.7V were selected for use in our throttles.

With cells rated at 3.7 and the input need for the throttles at 9V a DC to DC boot circuit is needed. Also a charge controller is needed to safely recharge the 3.7V lithium cell.

All these components along with a single 3.7V cell fit into the battery compartment of the throttle.

 

The cell can be recharged in place as the charge controller fits alongside the boost converter inside the battery compartment.

 

A switch was installed on the base of the throttle to turn it off when not in use.