Battery mod project for Tello

[Ricardo Penders]

UPDATE!! New battery cells with higher capacity, 1500mAh to be tested today!​

Hey everyone, I found new battery cells in a camera that fit into the original battery housing but these are 1500mAh and I'm charging them at the moment and I'm going to test the Tello later today to see how long it can fly with bigger capacity cells.

I've tested the 1000mAh battery cell which is new and got about 8 minutes of flight time, the new battery cells are 1500mAh so if I have to guess I might get about 20 minutes of flight time.

But I'll make a video of it, I have 2 of the 1500mAh battery cells and I've got the 1000mAh cell all charged up to be tested later.
I'll make a screen recording of the whole test and upload it to YouTube and I'll come back here and share the link so you can watch and see exactly how much flight time I now have with the new battery cells.

 

[Ricardo Penders]

UPDATE!! The new cells didn't work...​

So I've tested the two new battery cells and they do work, I can connect to the Tello, I can activate the motors and I managed to take off just for a second or two and then the Tello cuts out because the new battery cells can't deliver the necessary power and I suspect because of that the voltage sags and that's what the Tello is measuring constantly.

It's all done in software which runs on the Tello, it's not that the battery itself has any smarts.

So I'm taking the new cells out again and use the one new battery cell from another drone that I got for free for testing and reviewing.

Those battery cells are only 1000mAh giving me about 8 minutes flight time which is better than no flight time at all and because the battery cells are already for a drone they can at least deliver the necessary power so I can at least fly the Tello again.

So the new plan is to try and get some single cell drone batteries on the cheap that have the right dimensions to fit in the original battery case and hope that I'll find some cells with a little bit higher capacity than the original Tello battery cells somewhere in between the 1200mAh and 1500mAh or even more if that's even possible and go with that.
I'll take the BMS off the new cells and solder the Tello BMS boards to the new cells as I've done with the drone cells I've already got and they work properly so I just keep doing that to keep my Tello flying for a couple more years.

I think that's the best way and cheapest way to go forward, I know that I'm not going to spend the crazy amount of money on new original Tello batteries those are way too expensive especially when you have to replace them every year or so.

 

[Hacky]

Thanks for your report.
The problem is that cells with higher capacity usually can serve only lower C-rates. I guess that the cells which have been selected by Ryze are already the best compromise.

 

[Ricardo Penders]

Thanks for your report.
The problem is that cells with higher capacity usually can serve only lower C-rates. I guess that the cells which have been selected by Ryze are already the best compromise.

I know for sure that the original cells aren't just some cells that you can buy anywhere, in fact I've contacted a factory directly and they said they can make me cells that will work but they can't make cells that can take the high voltage when the cells are fully charged, which is 4.2 Volts by the way and most cells just don't go that high safely or they won't last very long if you push 3.7V or 3.8V cells to the 4.2V.

If it wasn't so expensive to get a batch of cells made by the factory and I didn't have to order way too many cells for me alone I would push those cells regardless, I've charged 3.8V cells so many time to 4.2V without any issues I don't believe that it's as harmful to the cells as they make us believe it is.

I don't know exactly how many I have to buy to get them manufactured for me but if it's only 50 or 100 cells per batch that's way too many cells for me alone and way too much money that I'm willing to spend on it, I guess the option is still open if I could do it together with other people and share the burden or I must have a couple people that I can sell some batteries so I don't have to use hundreds of cells myself.

If anyone has an idea or if there are enough of you who want to collaborate on this project please let me know, I'm open to any suggestion.

 

[Hacky]

4.2 Volts would be a typical charge voltage for almost any Lithium cell. The difference of the Telle cells is that they are "HV" (high voltage) cell types already, which can be charged up to 4.35V.

 

[Ricardo Penders]

4.2 Volts would be a typical charge voltage for almost any Lithium cell. The difference of the Telle cells is that they are "HV" (high voltage) cell types already, which can be charged up to 4.35V.

Ah, okay that's what they mean with that.
Well I know for sure that the Tello batteries are not HV cells, they only get charged to 4.2 Volt maximum.
So normal cells would do fine I guess

 

[alihan]

Hi,

I am applying these bat mods as well. Currently I soldered the original battery out and soldered my own 1170mah 3.7V battery. The drone turns on and ready to flight OK. But it occurs two scenarios:

1) completely cancelling take off due to critical low battery error (even though I charged it fully)
2) propellers turning for couple of rotations and cancelling the take off due some unknown error and drone reboots itself


Is it possible that I overheat and burn some sensors in the PCB came our from original battery while soldering my custom lipo battery? Or do you think is there something else I am missing?

 

[Bowst]

Hi,

I am applying these bat mods as well. Currently I soldered the original battery out and soldered my own 1170mah 3.7V battery. The drone turns on and ready to flight OK. But it occurs two scenarios:

1) completely cancelling take off due to critical low battery error (even though I charged it fully)
2) propellers turning for couple of rotations and cancelling the take off due some unknown error and drone reboots itself


Is it possible that I overheat and burn some sensors in the PCB came our from original battery while soldering my custom lipo battery? Or do you think is there something else I am missing?

The second scenario also happened to me. So i replaced it with another toy drone battery and now it works.

 

[scbenoit]

In the spirit of battery adventures here, I ordered a pair of battery cells from AliExpress. One to be used to replace the cell in a dead Tello battery, and th other 'cause they came as a 2 pack.

The cell was a drop in replacement for the one in the original dead Tello battery. As others have indicated here, split the case, unsolder the old cell, solder in the new cell, and glue the case.

Battery was dead, non-flyable and now has 12 minute flight time on 3 power charge cycles so far. Once my other original battery gets. little more worn out, I'll swap the second cell into it.

 

[Bruchpilot]

Hello scbenoid,
Please link the battery from Aliexpress.
How did you open the original battery?

Thanks and regards

 

[christiaan]

I´ve 4 batteries. I charged them and made a short hover test:
batt1: unfortunately almost dead. 2 mins
batt2: still lives. 5-6 mins
batt3: same. Still has 6-7 mins
batt4: kinda ok. 11 mins

EDIT:
After flying all batteries empty, I recharged them and made a 2nd test. I hit the take off button as soon as the live feed came on and let the drone hover till auto land. The situation is not that bad. Results:
batt1: 6:12
batt2: 8:57
batt3: 7:40
batt4: 11:58

My problem is, that I don´t fly Tello any more. One is in a bad shape, don´t hover normal, flies all over up and down, left and right. The other one is excellent, but I sold the goggles, because I have 2 Neos and 2 Avata 2s with goggles etc. Flying with a Tello LOS is boring...

 

[christiaan]

Hello scbenoid,
Please link the battery from Aliexpress.
How did you open the original battery?

Thanks and regards

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[scbenoit]

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Yes, that's pretty much the process I followed. I'm going to do a second battery so will take some pictures and video.

The AliExpress link I purchased from doesn't work now, and that was only a month ago when I ordered, they did take 5 weeks to arrive. But at time of purchase the expected arrival was 8 weeks out, so 5 was 3 weeks early.

I'll update more when I do the second battery, thanks for sharing that video link

 

[christiaan]

Yes, that's pretty much the process I followed. I'm going to do a second battery so will take some pictures and video.

The AliExpress link I purchased from doesn't work now, and that was only a month ago when I ordered, they did take 5 weeks to arrive. But at time of purchase the expected arrival was 8 weeks out, so 5 was 3 weeks early.

I'll update more when I do the second battery, thanks for sharing that video link

I think, there are more videos, this was the 1st one I found. Short and shows everything.

I order a lot from AliExpress lately, the average shipping time 10-12 days (incl weekends). 5 weeks good lord, half a lifetime...

 

[scbenoit]

yes, other components on the same ordered arrived in a timely fashion, jus 4th batteries were that long ... but had been told even longer when I ordered

 

[scbenoit]

OK, I found th link for the batteries I ordered from AliExpress

https://www.aliexpress.com/item/1005005865429869.html

This one seemed cheaper than all the others selling the lipos like this. But they arrived (price was for a pair of them) and they worked. I used one in a completely dead Tello FullyMax battery , and it's been doing good. Other one will soon go into a tello battery that only has 6 minutes flight time now.

The first repaired battery has been doing 11 min, 45 second flights over the last week or so of daily or twice daily flying.

 

[Bruchpilot]

Hello scbenoit, thanks for the information.
I opened the first battery; the two halves are glued together; you have to carefully cut around the edges until the battery is visible.
I previously tried discharging the old battery, but the internal protection circuit prevents complete discharge, leaving a residual charge. Therefore, you have to be very careful when opening the case to avoid damaging the old battery.

Regards

 

[Bruchpilot]

Hello, I had to completely throw away the opened Tello battery because it emitted an unbearable, very unpleasant chemical odor. The actual battery cover is undamaged, and the housing came apart easily.
Has anyone else had this experience?

Regards

 

[quaddamage]

unbearable, very unpleasant chemical odor.

Hm, many people find the electrolyte odor "sweet" rather than "unpleasant".
But it is toxic, do not inhale it for too long.

Also, every drone battery excreets that a little. Only people who store all the batteries in a sealed box notice - after opening such a box, it is always there.

If one small Tello battery emits enough odor to be noticeable, then the cells must be physically damaged. The offending cell will dry out pretty soon and stop working.

 

[Bruchpilot]

Hello quaddamage,

Thanks for the information.
Yes, there was also a sweet smell, very intense, but there was no visible damage to the battery's outer casing.

Best regards