Originally Posted by SlowerOne

No, but have used it in 4-cell. It is a capacitor that ensures that the receiver always sees a voltage above its minimum. NiMh cells can be dragged below this momentarily under hard acceleration at the end of a run. For that purpose it works perfectly.

In 1S, the voltage is too low to power the speedo and servo, and most receivers. To ensure that the speedo and receiver work, and the servo runs at a reasonable speed, it is necessary to supply 5v+ through a booster or external pack (see posts above about receiver packs) and that means a capacitor like this is not needed. HTH