Lipos for this transmitter would cost anywhere from 2 to 3 times the cost of 18650 batteries whose price starts below 500php for a pair or about 10usd and even lower if you’re going the 2nd hand route. I got some 2nd hand 18650’s for below 2usd a piece. Add to that the hassle of, most probably, getting the battery at the customs office as most countries have restrictions on importing batteries. Also, the capacities of 18650’s can match or exceed those aforementioned lipos. You can either go straight to soldering some JR connectors to the battery or use an 18650 tray which costs 1~2usd. I, personally, would choose the tray route as you can still use the battery for other stuff such as portable fans. To use the tray, you’ll have to mod it first to make it fit the MT-44’s compartment. Here I’ll show you how I did mine. Just needed some cutting and grinding/sanding and of course soldering connectors to it. I’ll link all items used/needed at the bottom of the article.
I started by cutting and grinding the tray. Only one half of the tray needs to be modded. A JR style connector was also soldered to the tray. You can either get separate JR connectors and crimp them or if you’re lazy like me, cut one off some other stuff like the AAA tray the MT-44 comes with. See pics for reference.
Then it just fits into the battery compartment. I cut out a sponge to keep it in place. You don’t really need to but I like it to be a snug fit. For the sponge, I actually used an rc chassis bumper
It’s also lucky that this tray has a notch in it that makes it fit well with the MT-44’s screw tunnel.
You can then set a custom battery profile for it or not. I did as the 18650’s lowest voltage is 2.5v. Unfortunately, the MT-44’s lowest voltage only goes as low as 2.7v. Not that big of a deal as that already is a really long ON time. For my battery, rated at 3350mah, it lasts over 24 hours and that was when I set my cutoff to 3.0v.
UPDATE: Set my low voltage cutoff at 2.7v and it lasted me over 29 hours. I could still run it for a few minutes probably but just didn’t want to wait till my tx totally shut off. Battery charged 3196mah.
ITEMS LIST (with links):