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Help! Transmitter battery upgrade


Active member
Hi guys, I've got a couple of lipos I bought for silly money (at the time) but have never used them nor do I have the dedicated charger for them. The pictures are of one of the batteries but both sides.
I need to do something about my tranny batteries now they've all finally bitten the dust and want to do something better than simply buying replacements which simply do not last long enough for a flying session.
My plan is to use one of the packs for my transmitter.

Anyway, enough waffle, my question is I assume the circuitry is voltage protection but could also be charge protection considering the complexity of the circuits. Anyone have any ideas?
The main question is do I cut the circuit out and just have the 2 cell packs wired up to a balance lead?
The transmitter has a low voltage alarm (and readout) and my chargers will charge it properly.
Should I keep the circuitry and trust it won't affect the tranny or charger?



Well-known member
I don’t think I would use the battery in my Tx with the circuit. That said, a new Tx battery is pretty cheap, I’m not sure it is worth the effort.

If the battery will fit & the voltage is within range, it should work.


Active member
Original new batteries for the tranny don't even last a flying session so that's why I'm wanting to put a bigger one in there. I've always just bought new ones but I've got to change my ways. Thanks for your reply.
Last edited:


Active member
So I split one of the batteries and removed the circuit board.
I made a new board which just sits on the end and allowed me to simply connect the cells in series and add a balance lead as well as a power lead.
I finished it off by gluing foam board either side of the new pcb and then shrink wrapped the entire thing.

I cut the worst battery I have up to get the connections for the tranny with the battery base which slots in the tranny.
Unfortunately the tags broke off the back of the connectors and I couldn't get a safe joint on the connectors themselves so I cut 2 short lengths of brass tube and drilled the end out to suit. I soldered my power wires to those then after pulling the originals out glued the new ones in place. As I had the glue gun out I got carried away and levelled the tray off he he.

I've put some Velcro on the outside battery cover and some on the pack and I just run the wire out of the slightly open cover. I've put a bit of foam board in to stop it shutting on the wire but I'll print a proper assembly to latch it soon.

After realising my balance plug wiring was a bit off (i thought i could wire 2c into a 3c plug by missing a wire, i eventually cut the plug down to a 3 way) it started taking a charge and when it got to 2200 mah (power of original batteries) I stopped it and tried it, success :) I've since run it down to 19% which is when the tranny low battery alarm starts going off (still can't work out how to silence or adjust it's level after all these years lol) so now I'll give it a full charge to 3300 mah and see if the tranny takes it ok.

Already it's outlasted my old batteries and it's not had a full charge yet. I'm happy so far.