A 3 cell LiPo in a RC Transmitter 2

Can a 3 cell LiPo be used safely in a transmitter that was designed for a 8 cell NiCad or NiMh pack?

It will operate fine from a 3 cell Lipo.

The main advantages of the LiPo are larger capacity and very low self discharge. The biggest danger is leaving the transmitter on and running it flat; been there done that. Another disadvantage is that you should remove it to charge it.

The low voltage alarm will be a bit low for a 3C LiPo; probably 8.5-9V. It may be possible to change the alarm voltage but that will depend on the transmitter.

I’ve been using a 3C 2650 for 2+years. Last year I did leave it on over night in the car and ran it flat (less than 3V), so I was back to NiMh for a few weeks. I charged, cycled and tested it thoroughly and it’s still going strong. It’s on for 1-2 hours a week and gets charged every 3 months, when it drops below 10.5V.  Mostly on 35MHz, which uses more power than 2.4G.

35Mhz transmits more power (and wastes more power) with higher voltage from a fresh charge; the module gets hotter. 2.4G transmits the same power throughout the battery discharge but there will be a bit more heating inside the radio at the higher voltage.

There are videos and threads explaining a mod that significantly reduces the power loss in a 2.4G transmitter with a 3C LiPo making it last even longer. Lots of work and easier to charge it more often.

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2 thoughts on “A 3 cell LiPo in a RC Transmitter

  • PMB

    My transmitter has a voltage alarm built in but it’s not very loud. It also beeps when it’s left on and not used for a time.
    I have been thinking of making a add-in auto-cutoff to switch the transmitter off and save the battery if the radio is left for too long. But It must not turn the radio off while flying.

  • Bede

    Just getting into the hobby myself, and got haemorrhaged at the shop for $18 for 8 aa batteries….

    Why don’t you attach a lipo low voltage detector inside the transmitter.