OT: DJI or similar drones...

[John Doe]

I thought DJI was expensive, but Autel is almost twice the price for an
entry-level drone. The less expensive drone makers use C.R.A.P. technology
and other weirdness like not selling additional propellers and whatever
other parts. Can\'t believe how cheap lesser brand controllers are compared
to DJI. The phone holder on even $300 drones is a single plastic plunger
with a simple spring inside the controller for tension! You can hear the
spring creaking.

DJI messed up the firmware or software for the Mini 2, so I\'m waiting to
get back into FPV flight with that one.



https://www.ebay.com/itm/175008269834

The seller accepted $300 for that old technology DJI Mavic Air (Arctic
White).

Additional batteries are OUTRAGEOUSLY expensive, at least twice the price
of other DJI drone batteries.

Can the provided battery shell be used as a connector for homemade
batteries?

Of course there are only 2 terminals to the actual battery inside of the
shell, so they can be connected to whatever batteries that will work
(Sanyo NCR2070C sourced enough current to work well in prior tests with
another drone). Lipo is ideal, but that Sanyo \"C\" model sources lots of
current.

Besides measuring temperature, what other connectors might be related to
the battery? I suppose any temperature sensor can be left hanging (with
the appropriate caution).

I suppose they could defeat battery mods by trying to communicate with the
battery circuitry, but apparently not since there is AFAIK no mention of
that by anybody who has tried connecting batteries to it.

 

[John Doe]

\"reset your battery with a ev2300 adapter, and software\"

Uhg. Seems swapping batteries might not be easy.

 

[Jan Panteltje]

On a sunny day (Thu, 7 Apr 2022 15:31:20 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2n048$9nh$1@dont-email.me>:

I thought DJI was expensive, but Autel is almost twice the price for an
entry-level drone. The less expensive drone makers use C.R.A.P. technology
and other weirdness like not selling additional propellers and whatever
other parts. Can\'t believe how cheap lesser brand controllers are compared
to DJI. The phone holder on even $300 drones is a single plastic plunger
with a simple spring inside the controller for tension! You can hear the
spring creaking.

DJI messed up the firmware or software for the Mini 2, so I\'m waiting to
get back into FPV flight with that one.



https://www.ebay.com/itm/175008269834

Depends on what you want, I would not want that, only smartphone app control?
I have this:
http://panteltje.com/panteltje/quadcopter/index.html
added some stuff to it, auto pilot, HUD.
Not been flying here, drone flights are prohibited here close to the mil airport.
No idea if it still available and at what price.

 

[John Doe]

Jan Panteltje wrote:

John Doe wrote:

I thought DJI was expensive, but Autel is almost twice the price for an
entry-level drone. The less expensive drone makers use C.R.A.P.
technology and other weirdness like not selling additional propellers
and whatever other parts. Can\'t believe how cheap lesser brand
controllers are compared to DJI. The phone holder on even $300 drones is
a single plastic plunger with a simple spring inside the controller for
tension! You can hear the spring creaking.

DJI messed up the firmware or software for the Mini 2, so I\'m waiting to
get back into FPV flight with that one.

https://www.ebay.com/itm/175008269834

Depends on what you want, I would not want that, only smartphone app
control? I have this:

http://panteltje.com/panteltje/quadcopter/index.html

added some stuff to it, auto pilot, HUD. Not been flying here, drone
flights are prohibited here close to the mil airport. No idea if it
still available and at what price.

It includes a controller, but I\'m having a tough time figuring out how to
power it.

Thinking about using the stock battery circuit, putting a capacitor across
its power pins, with a battery plug out from that, so batteries can be
swapped on that plug without trashing the battery circuit. Assuming the
capacitor holds up during the swap, there would be a big jump in voltage
when the new battery is plugged in, but maybe that wouldn\'t trash the
circuit. Don\'t know if keeping that circuit plugged into the drone, or
not, would matter while swapping batteries at the plug point.

I remember long ago looking at digi-key capacitors and seeing gold
capacitors, like 1 farad, but a quick search shows no such results.
Capacitor weight or size might be an issue, too.

 

[John Doe]

https://industrial.panasonic.com/ww/products/pt/edlc-wound-type

That might be related to what I recall. Those gold capacitors have been
discontinued. As I recall, they looked much stubbier than those.

Need high capacity (for removing and replacing a battery, don\'t know what
the current is), at least 10 V, small and light as possible.

 

[John Doe]

But I can try with some ordinary large capacitor first.

 

[John Doe]

Or maybe a tiny battery with a diode and maybe a resistor.
Would be nice to know the input impedance, bias current, whatever.





I wrote:

Need high capacity (for removing and replacing a battery, don\'t know what
the current is), at least 10 V, small and light as possible.

 

[Jan Panteltje]

On a sunny day (Thu, 7 Apr 2022 20:14:55 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2ngnv$g2k$1@dont-email.me>:

Thinking about using the stock battery circuit, putting a capacitor across
its power pins, with a battery plug out from that, so batteries can be
swapped on that plug without trashing the battery circuit. Assuming the
capacitor holds up during the swap, there would be a big jump in voltage
when the new battery is plugged in, but maybe that wouldn\'t trash the
circuit. Don\'t know if keeping that circuit plugged into the drone, or
not, would matter while swapping batteries at the plug point.

I remember long ago looking at digi-key capacitors and seeing gold
capacitors, like 1 farad, but a quick search shows no such results.
Capacitor weight or size might be an issue, too.

Those are called \'super capacitors\' or \'ultra capacitors\' it seems, there is a youtube video of a guy starting his car with one.,
https://www.ebay.com/b/Supercapacitor-Ultracapacitor-Industrial-Capacitors/4662/bn_114823789

 

[Jan Panteltje]

On a sunny day (Thu, 7 Apr 2022 20:27:47 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2nhg3$fj7$1@dont-email.me>:

https://industrial.panasonic.com/ww/products/pt/edlc-wound-type

That might be related to what I recall. Those gold capacitors have been
discontinued. As I recall, they looked much stubbier than those.

Need high capacity (for removing and replacing a battery, don\'t know what
the current is), at least 10 V, small and light as possible.

Super capacitors usualy have low voltage ratings, maybe some in series?

 

[Jan Panteltje]

On a sunny day (Thu, 7 Apr 2022 21:47:08 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2nm4s$g0g$1@dont-email.me>:

Or maybe a tiny battery with a diode and maybe a resistor.
Would be nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project,
but you lose a few hundred millivolts.
Use a Schottky diode perhaps, those have very low voltage drops.

 

[John Doe]

Jan Panteltje wrote:

John Doe wrote:

Or maybe a tiny battery with a diode and maybe a resistor. Would be
nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project, but
you lose a few hundred millivolts.

From a lithium battery? How long without the drone battery?

> Use a Schottky diode perhaps, those have very low voltage drops.

Thanks.

Maybe a lithium backup battery will work, if the diode prevents any
damaging trickle charge.

I wonder if lithium coin cells are rechargeable. Searching Google for
something like...

are lithium coin cells rechargeable?

....produces the most annoying possible NON-ANSWER results.

Will first try a Rubicon 10mF 25v capacitor since that\'s slamdunk easy.

Will reference a procedure for un-bricking the circuit, as needed.

 

[John Doe]

Jan Panteltje wrote:

John Doe wrote:

Or maybe a tiny battery with a diode and maybe a resistor. Would be
nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project, but
you lose a few hundred millivolts.

How long without the drone battery?

This would be no more than seconds, while swapping batteries.

> Use a Schottky diode perhaps, those have very low voltage drops.

The reverse leakage current won\'t destroy a CR3032 (or smaller) battery?

The drone battery starts at about 14 V.



If it lasts a long time, sounds great. Even if the drone battery voltage
drops slightly below the coin battery, that would only adjust the coin
battery voltage downwards.

 

[Jan Panteltje]

On a sunny day (Fri, 8 Apr 2022 18:40:14 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2pvie$lv4$1@dont-email.me>:

Jan Panteltje wrote:

John Doe wrote:

Or maybe a tiny battery with a diode and maybe a resistor. Would be
nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project, but
you lose a few hundred millivolts.

How long without the drone battery?

No idea, my drone uses 10 amps at 7.4V (2 cells)
http://panteltje.com/pub/hubsan_h501s_current_test_full_throttle_IMG_6290.JPG
http://panteltje.com/pub/hubsan_h501S_current_test_idle_IMG_6281.JPG

This would be no more than seconds, while swapping batteries.

Use a Schottky diode perhaps, those have very low voltage drops.

The reverse leakage current won\'t destroy a CR3032 (or smaller) battery?

The drone battery starts at about 14 V.

So almost 1 A idle...
A coin battery won\'t do that, a small 2 cell (or 3 cell if 14 V) lipo with diode will,
got a lot of those 1 cell lioos from ebay:
http://panteltje.com/pub/single_cell_lipo_protection_IMG_5486.JPG
Just put those in series..
That strip is a charge controller / protection (MOSFET in it), also from ebay.

 

[John Doe]

Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

John Doe wrote:
Jan Panteltje wrote:
John Doe wrote:

Or maybe a tiny battery with a diode and maybe a resistor. Would be
nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project, but
you lose a few hundred millivolts.

How long without the drone battery?

No idea, my drone uses 10 amps at 7.4V (2 cells)

http://panteltje.com/pub/hubsan_h501s_current_test_full_throttle_IMG_6290.JPG

http://panteltje.com/pub/hubsan_h501S_current_test_idle_IMG_6281.JPG

I had one like that (H501S, with the big controller).

This would be no more than seconds, while swapping batteries.

Use a Schottky diode perhaps, those have very low voltage drops.

The reverse leakage current won\'t destroy a CR3032 (or smaller)
battery?

The drone battery starts at about 14 V.

So almost 1 A idle... A coin battery won\'t do that, a small 2 cell (or 3
cell if 14 V) lipo with diode will, got a lot of those 1 cell lioos from
ebay:

http://panteltje.com/pub/single_cell_lipo_protection_IMG_5486.JPG

Good soldering.

Just put those in series.. That strip is a charge controller /
protection (MOSFET in it), also from ebay.

I\'m talking about swapping batteries. The thing is OFF, not idle. I will
know soon enough.

Mavic Air (1) batteries are outrageously expensive, but I got a new kit
for $300 (US). So the question is, how to use non-DJI lipos. Seems odd no
one else has tried.

There are some poorly made videos with insufficient instruction. There is
a Russian guy\'s video using a stock battery shell to hold 18650s. Some use
an Air 2 (the sequel) battery in a stock battery shell. But seems to me we
can use a single stock battery shell and just swap the batteries. If it
works, that will be by far the cheapest method.

AFAIK, the only problem is keeping the battery management system (BMS)
V+ pin from dropping below some cutoff voltage, while swapping batteries.

 

[Jan Panteltje]

On a sunny day (Sat, 9 Apr 2022 07:39:27 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t2rd7f$526$1@dont-email.me>:

Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

John Doe wrote:
Jan Panteltje wrote:
John Doe wrote:

Or maybe a tiny battery with a diode and maybe a resistor. Would be
nice to know the input impedance, bias current, whatever.

Diode should work, I have done that as backup in an other project, but
you lose a few hundred millivolts.

How long without the drone battery?

No idea, my drone uses 10 amps at 7.4V (2 cells)

http://panteltje.com/pub/hubsan_h501s_current_test_full_throttle_IMG_6290.JPG

http://panteltje.com/pub/hubsan_h501S_current_test_idle_IMG_6281.JPG

I had one like that (H501S, with the big controller).

This would be no more than seconds, while swapping batteries.

Use a Schottky diode perhaps, those have very low voltage drops.

The reverse leakage current won\'t destroy a CR3032 (or smaller)
battery?

The drone battery starts at about 14 V.

So almost 1 A idle... A coin battery won\'t do that, a small 2 cell (or 3
cell if 14 V) lipo with diode will, got a lot of those 1 cell lioos from
ebay:

http://panteltje.com/pub/single_cell_lipo_protection_IMG_5486.JPG

Good soldering.

Just put those in series.. That strip is a charge controller /
protection (MOSFET in it), also from ebay.

I\'m talking about swapping batteries. The thing is OFF, not idle. I will
know soon enough.

Here I cannot follow you
If the drone is \'off\' what difference does a small voltage interrupt make when changing batteries?
In my case after \'drone power off\' it will have to re-get GPS and also you
need to calibrate the drone\'s 4 axis compass system by turning and moving it.
So then keeping power makes sense (but usually calibrating only takes a minute or so, so no tricks needed).

Mavic Air (1) batteries are outrageously expensive, but I got a new kit
for $300 (US). So the question is, how to use non-DJI lipos. Seems odd no
one else has tried.

300 USD batteries and 20 minutes flying time ? Not a good deal.
Mine can extend fying time by adding an other lipo in parallel to past 30 minutes,
or use a bigger battery (strapped under the drone),

There are some poorly made videos with insufficient instruction. There is
a Russian guy\'s video using a stock battery shell to hold 18650s.

I have tried that sort of batteries, and expensive liion Sony cells:
http://panteltje.com/pub/liion_cells_storage_IMG_6338.JPG

Not better but worse than lipos!

Batteries for my drone are about 12 USD upwards:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=7.4V+2700mAh+30C+Lipo+Bat&_sacat=0

Some use
an Air 2 (the sequel) battery in a stock battery shell. But seems to me we
can use a single stock battery shell and just swap the batteries. If it
works, that will be by far the cheapest method.

AFAIK, the only problem is keeping the battery management system (BMS)
V+ pin from dropping below some cutoff voltage, while swapping batteries.

See above.

 

[John Doe]

Jan Panteltje wrote:

John Doe wrote:

I\'m talking about swapping batteries. The thing is OFF, not idle. I
will know soon enough.

Here I cannot follow you. If the drone is \'off\' what difference does a
small voltage interrupt make when changing batteries?

You are thinking about simple lithium-ion batteries.

DJI batteries have an integrated battery management system (BMS).

Naturally there are only 2 leads to the battery cells in the battery pack.
I need to figure out what the required input bias current is, and to
satisfy that during the few seconds in which the battery will be swapped.
The voltage cannot drop below a certain level, or the BMS will stop
functioning and cripple that battery pack (it can be hacked back to life).
The other concern is the big voltage jump the BMS will sense when the
battery is swapped.

There are some poorly made videos with insufficient instruction. There
is a Russian guy\'s video using a stock battery shell to hold 18650s.

I have tried that sort of batteries, and expensive liion Sony cells:

http://panteltje.com/pub/liion_cells_storage_IMG_6338.JPG

Not better but worse than lipos!

Because of the limited discharge rate. Anything short of the highest
discharge lithium-ion (like Sanyo NCR2070C, 30A) don\'t work, in my tests.
And of course that depends on the specific drone. Mine increased flying
time, but the drone was just hovering around during tests. If you are
actually outside flying like usual, the current requirements probably
exceed any lithium-ion battery.

 

[John Doe]

There might be more than 2 terminals to the batteries, since there are 3
batteries and their voltages are displayed.

Opening the module without damage is easy, with a small vice. Stick it in
there and squeeze, about 1 inch of the rear, about 1/8 inch deep to cover
along the cap portion. In other words... Grab about 1 inch worth of the cap
portion of the module (the back end), and squeeze. The back part of the cap
pops right off and you can use a tiny screwdriver to unclip the rest.




--

I wrote:

I thought DJI was expensive, but Autel is almost twice the price for an
entry-level drone. The less expensive drone makers use C.R.A.P. technology
and other weirdness like not selling additional propellers and whatever
other parts. Can\'t believe how cheap lesser brand controllers are compared
to DJI. The phone holder on even $300 drones is a single plastic plunger
with a simple spring inside the controller for tension! You can hear the
spring creaking.

DJI messed up the firmware or software for the Mini 2, so I\'m waiting to
get back into FPV flight with that one.



https://www.ebay.com/itm/175008269834

The seller accepted $300 for that old technology DJI Mavic Air (Arctic
White).

Additional batteries are OUTRAGEOUSLY expensive, at least twice the price
of other DJI drone batteries.

Can the provided battery shell be used as a connector for homemade
batteries?

Of course there are only 2 terminals to the actual battery inside of the
shell, so they can be connected to whatever batteries that will work
(Sanyo NCR2070C sourced enough current to work well in prior tests with
another drone). Lipo is ideal, but that Sanyo \"C\" model sources lots of
current.

Besides measuring temperature, what other connectors might be related to
the battery? I suppose any temperature sensor can be left hanging (with
the appropriate caution).

I suppose they could defeat battery mods by trying to communicate with the
battery circuitry, but apparently not since there is AFAIK no mention of
that by anybody who has tried connecting batteries to it.

 

[John Doe]

*cells

 

[John Doe]

The item was factory sealed. The battery is functional. Great price.

 

[John Doe]

I can get into the battery firmware using \"DJI Battery Killer\" (or similar)
and a hardware interface \"CP2112\" from my PC to the drone battery.

But not sure if using one battery management system (BMS) while swapping
batteries to that BMS is possible, at least not without adding two more
capacitors (or whatever stuff might be needed).