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.
Hello
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.
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.