OT: DJI or similar drones...

John Doe <always.look@message.header> wrote in
news:t3djc5$59t$5@dont-email.me:

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).
Click to expand...

My battery packs for my drone is ten inches long, three inches wide and
an inch and a half thick. My drone propellers are 10\" in diameter.

DJI? Bwuahahahahah! OK... mine is similar... it is a drone. But
it is way bigger than a DJI.
 
It works! At least preliminarily. It requires 1 10 mF capacitor and 3 1/10
W resistors. The capacitor drains fast when the battery management system
is not in power failure mode (a bit disappointing, but no big surprise),
but not too fast. On a 3s Mavic Air BMS, after unplugging the battery, the
cap went down to 9.2 V before it was re-plugged. Still functioned. Maybe
it can get down to at least 9 V. In any case, that probably is enough time
to switch batteries, unless you fumble the operation.

That is for using only one BMS circuit board and switching batteries to
it, as opposed to using one BMS per battery. It might be advantageous with
only one BMS circuit board available. For a Mavic Air, the required 10 mF
cap is only 14 g, the 3 1/10 W resistors are weightless. The resistors are
used as a voltage divider so the BMS thinks the battery midpoints are
connected.







I wrote:

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).
Click to expand...
 
John Doe <always.look@message.header> wrote in
news:t3e55u$lkj$1@dont-email.me:

It works! At least preliminarily. It requires 1 10 mF capacitor
and 3 1/10 W resistors. The capacitor drains fast when the battery
management system is not in power failure mode (a bit
disappointing, but no big surprise), but not too fast. On a 3s
Mavic Air BMS, after unplugging the battery, the cap went down to
9.2 V before it was re-plugged. Still functioned. Maybe it can get
down to at least 9 V. In any case, that probably is enough time
to switch batteries, unless you fumble the operation.

That is for using only one BMS circuit board and switching
batteries to it, as opposed to using one BMS per battery. It might
be advantageous with only one BMS circuit board available. For a
Mavic Air, the required 10 mF cap is only 14 g, the 3 1/10 W
resistors are weightless. The resistors are used as a voltage
divider so the BMS thinks the battery midpoints are connected.


I wrote:

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).


Having \"right to repair\" issues with a lame manufacturer?
Click to expand...

You should see what Taylor and McDonalds did to its franchises.
 
On a sunny day (Sat, 16 Apr 2022 10:18:38 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t3e55u$lkj$1@dont-email.me>:

>It works! At least preliminarily. It requires 1 10 mF capacitor and 3 1/10

The \'m\' stands for \'milli\'
I take it you did mean \'uF\' \'micro Farad\'


For the ret I still have no idea what you are doing.
But my drone works.
 
Jan Panteltje wrote:

John Doe wrote:

It works! At least preliminarily. It requires 1 10 mF capacitor and 3
1/10

The \'m\' stands for \'milli\'
Click to expand...

Very good! At 14 g, a Rubycon PX 10 mF cap from Digi-Key seems to work.

Putting that cap across the V+ and V- terminals of the battery management
system seems to keep the BMS from dropping below its power failure mode
cutoff voltage (or doing any other mischief) when swapping batteries.

Usually a DJI drone user swaps batteries with each having an integrated
BMS circuit board, but this (preliminary) solution requires only one BMS.

Used 6.8 k resistors for a divider to the otherwise unconnected battery
midpoints. Maybe 10 k will work.
 
On a sunny day (Sat, 16 Apr 2022 17:35:25 -0000 (UTC)) it happened John Doe
<always.look@message.header> wrote in <t3euot$ej4$1@dont-email.me>:

Jan Panteltje wrote:

John Doe wrote:

It works! At least preliminarily. It requires 1 10 mF capacitor and 3
1/10

The \'m\' stands for \'milli\'

Very good! At 14 g, a Rubycon PX 10 mF cap from Digi-Key seems to work.

Putting that cap across the V+ and V- terminals of the battery management
system seems to keep the BMS from dropping below its power failure mode
cutoff voltage (or doing any other mischief) when swapping batteries.

Usually a DJI drone user swaps batteries with each having an integrated
BMS circuit board, but this (preliminary) solution requires only one BMS.

Used 6.8 k resistors for a divider to the otherwise unconnected battery
midpoints. Maybe 10 k will work.
Click to expand...

OK, thanks, think I got it now :)
 
The big capacitor discharges down to at least 8 V (to a BMS for a 3s
battery) before the circuit locks up. That\'s probably PLENTY of time to
swap batteries.

The reason is to convert DJI drones to use ordinary lipo batteries,
especially ABANDONED DJI drones with unbelievably high-priced batteries.

I suppose having 3 outputs, maybe 1\" long each, from the battery
management system won\'t hurt anything since it\'s ground and two digital
signal lines. I suppose capacitance might be a factor but I don\'t know how
long of a wire has an effect on that on the given circuit (or even
generally).

Those wires are for resetting the BMS in case the capacitor does discharge
too far. The reset is a simple process. Apparently completely discharging
the capacitor is required, maybe to reboot the BMS before reseting it.

Not sure I\'ll use it, but looks like a possibility. Apparently they
corrected FPV mode on the Mini 2 (they temporarily messed it up). So now
it probably is a better FPV experience than the Mavic Air (1).

Learning how to coordinate movements with the joystick. STEEP learning
curve.







I wrote:

It works! At least preliminarily. It requires 1 10 mF capacitor and 3
1/10 W resistors. The capacitor drains fast when the battery management
system is not in power failure mode (a bit disappointing, but no big
surprise), but not too fast. On a 3s Mavic Air BMS, after unplugging the
battery, the cap went down to 9.2 V before it was re-plugged. Still
functioned. Maybe it can get down to at least 9 V. In any case, that
probably is enough time to switch batteries, unless you fumble the
operation.

That is for using only one BMS circuit board and switching batteries to
it, as opposed to using one BMS per battery. It might be advantageous
with only one BMS circuit board available. For a Mavic Air, the required
10 mF cap is only 14 g, the 3 1/10 W resistors are weightless. The
resistors are used as a voltage divider so the BMS thinks the battery
midpoints are connected.







I wrote:

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).
Click to expand...
 
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