Using Li-Ion batteries in Sanwa MT-S transmitter

[factory team gair]

Using Li-Ion batteries in Sanwa MT-S transmitter

(Check your TX for compatibility with other batteries)

The standard battery in the MT-S is 4xAA dry cells or Nimh cells if you use rechargeables. This works well in the transmitter because these batteries are cheap and easy to get, and the radio is efficient, so you’re not changing batteries too often. However, if you race a lot or for a long time like a long nitro main, you might drain them while racing - a bad thing. Switching to Li-Ion (or Lipo) could help in a few ways:

Lighter - An appropriate Li-Ion or Lipo battery will be lighter than the usual 4xAA or 8xAA setup in most transmitters. The grams add up and could help with fatigue or radio balance. Which will be useful on long race days.

More capacity - Li-Ion and Lipo can easily have double the energy density of AA’s, so you get more voltage and more mAh

Possible TX signal boost - I haven’t opened up my radio to see if there’s any type of regulator in use. There is the possibility that more power from the battery will translate into more power in the signal.

Less chance of confusing charger settings - Race days can be hectic and switching charging profiles a lot can lead to a mistake where you end up charging Lipos with a NiMH profile and kill it, or just waste time. Converting your radio batteries over to the same chemistry as your buggy/bump box/RX pack will cut down on that possibility.

Cheap - You can buy 18650 cells for a few dollars on eBay, or scavenge them from an old laptop or tool battery that has stopped working. In the scavenging case, it is very normal that a cell or two, or a few have failed in the pack leaving most of the cells still perfectly usable. I picked up an old laptop pack with 6 18650 2250mAh Panasonic (good) cells in it for $7.

In the case of the Sanwa MT-S, it even has multiple cell configurations in the menu so that your alarms and cutoffs are set to right voltages. All I had to do was pair up a couple cells, use power and balance leads from other dead batteries, and solder it all together to give my radio a lot of extra juice! There was a little bit of cutting to the battery box to make room for the shape of the pack, but that only took 10 seconds with the dremel. I look forward to racing VRC everyday and long real race days with multiple classes without worrying about my radio batteries.

[youtube]https://www.youtube.com/watch?v=Js14OiW-mDc[/youtube]

[Basher67]

I can see the benefits of having a rechargable battery in theory, but I have a liFe battery (same concept) in my Futaba 4px and I find it is a pita. If there is one thing that I regularly forget to do, it is recharge my transmitter battery. This can lead to real problems if the low bat alarm suddenly goes off in the middle of a race or just before. It takes at least 30-45 min to charge it. This can lead to missing heats or even worse a main. My old transmitter used the standard 4 AA alkalines. I always carried a spare pack or two with my race bag. If I suddenly realized at the wrong moment that my bats were low, It was a 10 second fix. Good quality alkalines would last for a month of racing and practice, so the cost was negligible.

[Jools]

Yes good idea, but it might be as well to check voltages before you jump in, depending on your tranny, a 3-cell lipo at 11.1v might cook some tranny's, and a 2-cell at 7.4v might not have enough juice.
Hobby King stock a special LiFePO4 battery to suit 9.6v transmitters.
Specs:
Capacity: 1500mAh
Voltage: 3S1P / 9.9V
Discharge: 1C
Weight: 142g
Dimensions: 100mm x 31mm x 26.3mm
Balance Plug: JST-XH
Discharge Plug: Taranis / JR / Spectrum / Futaba
Note this LiFePO4 is rated at 9.9v not 11.1v as a normal 3-cell.

https://hobbyking.com/en_us/turnigy-nano-tech-1500mah-life-3s-9-9v-transmitter-pack-taranis-compatible-1.html

[factory team gair]

I can see the benefits of having a rechargable battery in theory, but I have a liFe battery (same concept) in my Futaba 4px and I find it is a pita.

You could get a backup LiFe battery for $20-$30

I have charged batts for 5 minutes just enough to get through mains before.

[factory team gair]

Yes good idea, but it might be as well to check voltages before you jump in, depending on your tran

exactly, radios are different brand to brand and even by series within the same brand, and year to year, so to it pays to check.
I was happy to find out that the MT-S could handle 4 dry, 4 nimh, 2 cell lipo, 2 cell life, and 2 cell lipo/liion