7.4 v servos

[Granddad]

Maybe a silly question, but how do you run 7.4 v servos if your reciever can only take 6v?

[Alan Cantwell]

radio systems are 4.8, or 6 volt, what are these strange servos?

[Bob Cotsford]

lot of 'em coming on the market, 7.4v receivers too but still in the minority.

If your rx is 6v, that is your limit, regardless of what your servos can cope with, unless you want to try a more complex split power supply system with 7.4v for the servos and a separate 5-6v supply for the rx.

Each servo would need +ve and -ve going to the 7.4v supply while signal and -ve go to the receiver outputs. -ve is Y'd to both.

[FlyinBrian]

Many modern RC systems rx's will accept more than 6V but until relatively recently the servos only took up to 6V. Spectrum advertise the rx as OK at 9.6volt so 2 lipo cells are fine but not with 6v servos! hence the various regulators etc used on larger models. Now with HV servos you can use 2 cell liposand have no need to worry about such regulators but make sure your RX is OK with the higher voltage first.

[Mark Powell 2]

All Mutiplex stuff is good from 3.5 right up till 9.0 (the specs say so) and has been for years. And they don't bother with this 'HV' marketing stuff. Receivers, servos, accessories, the lot. Never exceed the manufactures spec with any receiver, servos can usually take a little more and won't mind . Some JR servos are touchy if the voltage is higher than the spec.

[Andy Butler]

The HiTec Optima series of receivers have a Supplementary Power Connector (SPC) that can take up to 35V to power just the receiver to prevent brown outs. Servo power has to come from a separate battery pack or BEC/UBEC. I use the balance connector to connect to the SPC and the BEC connector (or UBEC) connected to another channel (Throttle channel, channel 3 usually) to power the servos. It works well, with the added benefit that the SPC voltage takes priority and is relayed to the transmitter as standard so I know what the voltage of the flight battery is doing. I suspect the the 7.4V will become standard so a 2S Lipo can be used as a flight pack instead of 4 or 5 Nimh cells.