9000mah Extended Battery (Experimental)

deakbannok · Nov 20, 2018

Here I am testing it with Samsung 21700 3s2p.
The only issue is the voltage. These are lithium cell with a max of 3.7-4.2 voltage. By default, the battery is Lipo about 4.35v on each serie.
By my calculation I can only pull 72% out of my 21700 battery befor the BMS is cut off at 11.4v.

deakbannok · Nov 22, 2018

Complete setup and ready to fly.

Bobjazz · Nov 22, 2018

How much more weight is it than the stock battery? Interested to see how much more flight time you get.

norman.hicks.35 · Nov 23, 2018

I’d worry that would upset the balance of the drone seeing as the extra weight isn’t centered.

Jagerbomb52 · Nov 23, 2018

Many of the Phantoms had modded batteries but they were attached under the UAV so they were not top heavy. I hope this will not be a Opppps type of moment for you. I applaud you Sir for at least trying. If it was not for people seeking something different the RC community would be back flying airplanes with elastic bands

Good luck with your experiment

Gsa103 · Nov 23, 2018

The racing quads routinely have batteries strapped well above center or below, and don't seem the worse for it. The flight performance may suffer some due to a little bit of balance issues, but the flight controllers can deal with amazing levels of abuse.

deakbannok · Nov 24, 2018

Only place to mount is the top to avoid interfering with the bottom sensors. 21700s are slightly heavier than a stock battery. But it is 4800mah each.

Here is my hovering test indoor. You can see the balance is slightly off. If there is any possibiliy chance to be able to change the battery parameter settings on Autel EVO for a voltage setting. This will push more than 30mins flight time. In general, the voltage cutoff on Autel EVO is 11.4v (or 3.8v on each cell) that is alot of unused power left in the battery pack. You can safely discharge to below 3.0v on each cell.

mixchief · Nov 24, 2018

I would be a little more concerned about the aerodynamics in outdoor flight than the balance indoors, side winds on a profile that large are surely going to take a toll and most likely make the motors work a lot harder consuming more power and making the additional power mast less than expected. Did you do a time check on hover indoors?

deakbannok · Nov 24, 2018

mixchief said:
I would be a little more concerned about the aerodynamics in outdoor flight than the balance indoors, side winds on a profile that large are surely going to take a toll and most likely make the motors work a lot harder consuming more power and making the additional power mast less than expected. Did you do a time check on hover indoors?

I did, 16mins hovering from a full charge 21700 cell 4.2v to 3.8v and the drone is forced land after the voltage is hit 3.8v.

I will do outdoor maneuverability flight test.

mixchief · Nov 24, 2018

Considering that the stock battery will do 23 minutes, does it make sense to do this mod?

deakbannok · Nov 24, 2018

@mixchief

to learn and experiment.

mixchief · Nov 25, 2018

deakbannok said:
@mixchief to learn and experiment.

I mean post test, I understand the experimentation and love the fact that you are taking the time to do it, but after testing you have shorter time, do you have a plan B,with the massive capacity increase one would think there will be gains. Sorry I am not technically saavy but I'm trying to understand.

Jagerbomb52 · Nov 25, 2018

From when I was looking into doing something like this for the X-Star it all comes down to the "C" rating of the battery and how fast the ESC,s discharge your battery under load. RC toys take different "C" rated batteries for a reason. My Yuneec Q500 batteries are rated at 10C but some RC trucks have 80C rated batteries. I had emails from Autel support asking what the C rating was for the X-Star they could not tell me which I really found surprizing as the call them selfs tech support.

deakbannok · Nov 25, 2018

@Agustine C rate is measured by how much current (Amps) can be discharged entire batttery pack in one hour without the damage. So if you have bought a battery pack 4300mah 10C.
(4300/1000) = 4.3A (10C) = 43A.

Autel EVO battery have 3(s) series (aka cell) of 4300mah with a nominal voltage of 11.4(v). Well is 13v+ but I will use the number from the back of the battery.

11.4v / 3s = LIPO 3.8v of 4300mah.

Now let say you can get around 25 mins of flight time per charge.
In the back of battery is indicated (4300mah * 11.4v)/1000 = 49.02 Watts per hour.

49.02Wh / 25min = Your drone uses 1.96WATTS per minute

1.96WATT * 11.4.V = average 22.4 amps.

So you need a battery pack with 20a+ discharge.

@mixchief What I will do next is try to bypass the voltage check (How? That will be post it up later). Because the drone will stop and force to land after your battery is at 10.5v and the BMS on your battery pack is cutoff. So you can't not turn the battery pack on.
There is no modification needed to the drone.
Just to a battery pack. Worse case will happen to me is, burn up the 100$ battery pack.

I have 2 main stock battery packs extra to fly the drone.

Ricklee · Dec 26, 2019

deakbannok said:
@Agustine C rate is measured by how much current (Amps) can be discharged entire batttery pack in one hour without the damage. So if you have bought a battery pack 4300mah 10C.
(4300/1000) = 4.3A (10C) = 43A.

Autel EVO battery have 3(s) series (aka cell) of 4300mah with a nominal voltage of 11.4(v). Well is 13v+ but I will use the number from the back of the battery.

11.4v / 3s = LIPO 3.8v of 4300mah.

Now let say you can get around 25 mins of flight time per charge.
In the back of battery is indicated (4300mah * 11.4v)/1000 = 49.02 Watts per hour.

49.02Wh / 25min = Your drone uses 1.96WATTS per minute

1.96WATT * 11.4.V = average 22.4 amps.

So you need a battery pack with 20a+ discharge.

@mixchief What I will do next is try to bypass the voltage check (How? That will be post it up later). Because the drone will stop and force to land after your battery is at 10.5v and the BMS on your battery pack is cutoff. So you can't not turn the battery pack on.
There is no modification needed to the drone.
Just to a battery pack. Worse case will happen to me is, burn up the 100$ battery pack. I have 2 main stock battery packs extra to fly the drone.

Just wonder if you have come up with any solution on the mod as I have asked help to modify my battery pack by replacing the cell inside with similar capacity, but the newly packed battery only giving around 16 minutes of hover time. Any thought.

Fly-a-holic · Dec 27, 2019

Ricklee said:
Just wonder if you have come up with any solution on the mod as I have asked help to modify my battery pack by replacing the cell inside with similar capacity, but the newly packed battery only giving around 16 minutes of hover time. Any thought.

If you have replaced your cells and you are getting less flight time, then either you used less capacity cells than the stock ones (despite what they are labeled) or you have used cells with a less "C" rating. Both will result in less flight time.