Tethered Tello attempt - would someone know better about tello's battery, power and electrical?

nicovernio · Oct 13, 2018

Hi there, I just recently bought a Tello to experiment about development (looking into how to make the drone follow a set path).

I thought it would be awesome to connect the drone to an external power source/cable instead of using the battery. The tethered drone would allow longer period of testing with keeping the contact established between the controller app and the drone itself and would make things a lot easier/funnier (despite the movement limitation).

I 3D printed a fake battery case, tinkered with a 5V power supply and tested various voltage repartitions across the 4 connectors, trying to duplicate the power I would get from probing the battery with a multi-meter (I tried GND, -5V, -5V, -3.7V or GND, -5V, -5V, -5V or GND, -4V, -4V, -4V).

On top of finding the battery output quite strange (why is it negative!?), I am wondering why I can not get anything working... no light, nothing at all, despite the connections and voltages seemed good enough. And that it is still working with the battery (always been quite worried about bricking the little thing).

Would anyone have experimented with the batteries and/or have ideas or direction? I am stuck and don't know what could be the problem/what else I could try.

Cheers!
Nick

RyanM · Mar 26, 2019

Hi Nick,

I am also trying to figure this out. Did you manage to get this right?

Cheers

bmelody · Mar 27, 2019

Check the polarity of your meter. Red to red (+) and black to black (-). If your leads are reversed you will read a negative voltage. Be sure the meter is set to DC Volts.

Here is a picture I found online that shows the 2 connections you will need. The other 2 connection are for temperature monitoring and not required for what you are attempting to do.

I verified the connections and they are correct. I would set your power supply to 4.0 VDC.

Best of luck, ~ Bill

nicovernio · Mar 27, 2019

RyanM said:
Hi Nick,

I am also trying to figure this out. Did you manage to get this right?

Cheers

Hello Ryan,

Sorry for late reply... no, I didn't look into it since that post. But may try again from what Bill is telling (and the photo he provided). I'll post here again depending on results, whenever I get it done.

After that, my idea was to waste $30, buying a spare battery, just to crack it open and find out how the battery is powering the whole thing exactly. But... well.

Let me know if you experiment and manage to make it work!

Cheers!

nicovernio · Mar 27, 2019

bmelody said:
Check the polarity of your meter. Red to red (+) and black to black (-). If your leads are reversed you will read a negative voltage. Be sure the meter is set to DC Volts.

Here is a picture I found online that shows the 2 connections you will need. The other 2 connection are for temperature monitoring and not required for what you are attempting to do.

I verified the connections and they are correct. I would set your power supply to 4.0 VDC.

View attachment 3555

Best of luck, ~ Bill

Hi Bill,

Thanks for the picture/information. I may have a look at it again soon from what you say.
Was there more info on the page where you found the picture? Could you maybe paste the link?

Cheers.

RyanM · Mar 28, 2019

Hi Nick and Bill,

This is great feedback. Will also attempt when I can. Hope this works - would be great!

Cheers

bmelody · Mar 28, 2019

Hi Guy's,

The picture I found was only a picture. However here is a link (video only, no audio) of a guy hooking up his Tello battery to an external charger.

~Bill

nicovernio · Mar 29, 2019

Hmm... I have seen this video already before. But could not make it work with my fake battery... thinking it may have been a connection issue. I guess I will end up cracking my battery open to use the case...

Thanks anyway for sharing!

I won't have time to look into it for a while, but will end up coming back to it and update here. Cheers!

avilahuerta · Apr 6, 2019

Hello,

I am also interseted in using the drone directly connected to a power supply with wires and without battery. The information that you have provided is very interesting. I have contacted Tello support and they tell me that this is not possible, but I am convinced that it should work. Probably what is needed is to connect also the other two contacts (pin s 2 and 4) somehow to give Tello circuitry the impression that a battery is connected and that no excessive temperature is happening. Does anybody know what type of overtemperature protection is available in Tello battery and internal circuits. It might be as simple as a thermistor thus a simple resistor could be used to "cheat" Tello. The question would be what is the right value for the resistor.

nicovernio · May 16, 2019

avilahuerta said:
Hello,

I am also interseted in using the drone directly connected to a power supply with wires and without battery. The information that you have provided is very interesting. I have contacted Tello support and they tell me that this is not possible, but I am convinced that it should work. Probably what is needed is to connect also the other two contacts (pin s 2 and 4) somehow to give Tello circuitry the impression that a battery is connected and that no excessive temperature is happening. Does anybody know what type of overtemperature protection is available in Tello battery and internal circuits. It might be as simple as a thermistor thus a simple resistor could be used to "cheat" Tello. The question would be what is the right value for the resistor.

Hi Avilahuerta,

Sorry for late reply... I could not really say. I have a fairly basical knowledge in electrical and electronic, which is far to be enough to understand how two pin could be used to detect overtemperature.

Like I explained. I mesured Voltages on the 4 contacts of the battery, and found a way to get the same output using cables, in my fake 3D printed battery case. But it is not working. So... I am not sure if either:
-current was not strong enough (not enough A)
-system is expecting voltage to do something once connected (maybe your idea to use a resistor would work?)
-or contacts was bad and power not going through at all

In my situation, without knowing better and thinking of the most plausible cause, I am planning to crack open the existing battery and see what is inside.

Then use the cracked shell to feed power through cables, knowing that connectors contact should be good.

But... well. This project have jumped down on my to do list. So not sure how long it will take me to convince myself to crack the battery. Not that I use my Tello much anymore, but... well. Breaking things is always a bit painful. ;-)