Help! Jumper T Pro batteries go flat when not in use


New member
Hey folks - infrequent poster from New Zealand here but long time fan of Flite Test.

I have a Jumper T Pro transmitter which I am very happy with as a lightweight option for carrying up our local volcanic peaks for slope soaring or using with my ragtag collection of small FrSky and Spektrum compatible electric park flyers. I fly only occasionally and ave found that if I leave the batteries in the TX, they gradually go flat even though the TX is powered off. But, if I remove them from the transmitter, the batteries retain their charge.

It seems the TX is slowly consuming power even when switched off. Because the battery covers are so awkward to get on and off, I would like to be able to leave the batteries permanently in the device without worrying about them being fully discharged, as I do with my FrSky Taranis.

It is a slow drop in voltage - I measured it after a full charge and after 26 days it went from 8.0v to 6.1v. I initially gave myself a bit of a fright after not using it for some months and finding it at 2.67v! Fortunately the relatively new 18650 Li-Ion batteries seemed to recover after a couple of days of charging.

I can't find threads about others having the exact same issue, though I have stumbled on some comments about a problem from people who may have had one of the radios from the "original batch" where the power to the external module stays on even though the TX is turned off. I don't use an external module, but I'm wondering if this fault might be responsible for slow depletion of voltage I am seeing. I can't find the fix for this, if there is one.

I emailed Jumper-RC support but no reply - makes me wonder if they are going to remain in business, particularly as RadioMaster seems to be overtaking them.

I'm considering whether I could improvise a physical power switch to be able to disconnect the batteries without removing them from the unit.

Suggestions appreciated. :)


New member
If you can't find a good simple solution through Jumper you could potentially add a switch inline off of the battery leads to physically cut the power to the radio.


New member
Thanks, good idea. I managed to PM one of the people who reported the problem with their external module not powering off and they responded to say that they contacted Jumper support and got a new motherboard sent out to them that fixed the problem. It was post #126 here:

I'll try Jumper support again, but they've gone a bit quiet on me recently so I might need to add an inline switch as you suggest.

This gear seems to be pretty cheap these days, so I should probably be a bit more relaxed about opening the case up and drilling holes in it etc. Or just buying a new RadioMaster transmitter. :)


Techno Nut
Most radios have a logical switch which powers off the display and radio modules, but the internal electronics are not all powered down. You can expect there to be long term drain if you do not disconnect the battery or charge it periodically.

If you open up your radio to do any sort of maintenance, disconnect the battery first! I found out the hard way working on my X9D+ that you can short out and kill the main processor board when the terminals on a switch get shorted out.


New member
Варочные котлы с доставкой по России от производителя
котел для варки сиропа
Компания "ЭкоКотёл" оказывает широкий спектр услуг по производству и доставке варочных котлов любого назначения.

Распродажа оборудования до конца месяца

Успейте заказать варочный котел по специальной цене в честь 10-летия компании
варочный котел купить

варочный котел купить


New member
Thanks for the tip, I'll make sure I disconnect the battery before I do anything.

It does seem that my particular Jumper T-Pro still has quite a significant drain on the battery when not in use. I sometimes go months without flying and distinctly remember one day getting my gear ready and finding that the Jumper T-Pro was completely dead but my own X9D+ was ready to go and hadn't experienced any dropoff in voltage at all.

I have never removed the batteries from my X9D+ and never experienced any such problem. Whereas, I don't feel it's safe to leave batteries in the Jumper T-Pro when I'm not using it. Thus, I'm having to fumble with the battery covers each time I want to use it - they are awkward to begin with and starting to deform with all the taking off and putting on again.