Surprised there is no third party solution to the Android charging from controller problem.
- Thread starter Lifeisfun
- Start date
Nice component.
Here's the problem: if the Android demands or tries to pull more current than the limiter allows, the voltage has to drop. If the voltage drops too low, the Android may drop the USB altogether.
Ohms law: V=IR. You can't get away from that. If Android applies an effective resistance to draw 500mA, and the limiter wants to cut the current down to 50mA, then the limiter has to drop the voltage.
Here's the problem: if the Android demands or tries to pull more current than the limiter allows, the voltage has to drop. If the voltage drops too low, the Android may drop the USB altogether.
Ohms law: V=IR. You can't get away from that. If Android applies an effective resistance to draw 500mA, and the limiter wants to cut the current down to 50mA, then the limiter has to drop the voltage.
That's been the experience for many when cutting the power lead and using resistors.
It seems one method does not fit all Androids. It seems to depend on USB hardware used and manufacturer implementation on power and charging, which is probably why DJI opted to adhere to USB 2.0 data standards: host must be able to deliver 500mA to a connected device.
It seems one method does not fit all Androids. It seems to depend on USB hardware used and manufacturer implementation on power and charging, which is probably why DJI opted to adhere to USB 2.0 data standards: host must be able to deliver 500mA to a connected device.
If you limit your considerations to passive devices, that is a simple series resistor, yes the load will see a voltage drop. A more elegant solution is to use an active current limiting device, the voltage won’t drop to any significant degree. 100ma is within the permissible lower limit under USB2 standards. What he opens when you use an undersized regulated PSU to drive a lipo charger? The battery will still charge, it just takes longer- the voltage doesn’t sag to any appreciable degree.
Yes but how is an active current limiter to limit the current on a given load trying to exceed the current limit? It's only option is to reduce voltage, usually through an active resistance which creates the drop.
Look again at Ohm's law.
Now the device being limited may see the drop quick enough to back off it's load which an active device will follow better than a passive one.
Also unlike a passive one, an active limiter will maintain the intended voltage as long as the current limit isn't exceeded so there is that.
Look again at Ohm's law.
Now the device being limited may see the drop quick enough to back off it's load which an active device will follow better than a passive one.
Also unlike a passive one, an active limiter will maintain the intended voltage as long as the current limit isn't exceeded so there is that.
Oh and we're talking about an Android, not a LiPo battery being charged. Unlike a USB LiPo charger, we still need the Android to maintain the data connection.
Anyone try connecting a USB volt/amp meter between an RC and iOS with iOS charge mode turned off?
Anyone try connecting a USB volt/amp meter between an RC and iOS with iOS charge mode turned off?
Have you tried reading the applicable USB standards? A USB2 device wont drop its data connection if it see's 100ma current available, it may disable charging though.
I stand corrected. But that applies to low power devices. High power devices can still fail at higher currents, though they need to start out at 100mA. Not sure what Androids classify themselves as and if that's uniform across all of them.
I guess a 560 ohm was too large. 50 ohm should work then, maybe a bit smaller.
Hopefully then the Android will see the limitation and not draw even 100mA continuously. 100mA is better than 500mA, but still can take a bit of a chunk out of the RC runtime.
I guess a 560 ohm was too large. 50 ohm should work then, maybe a bit smaller.
Hopefully then the Android will see the limitation and not draw even 100mA continuously. 100mA is better than 500mA, but still can take a bit of a chunk out of the RC runtime.
This is still working. The inline meter is for demo purposes only. Fly was also running and the screen had been set to bright. Notes: MC receiving 172 mA@5V and phone charging at 240 mA. The MC is still using more power than it is drawing but after 4 flight batteries it had 2 dots showing. Phone had charged to 99%.
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If you have a rooted phone? Battery charge limit?
This thread is old and no one mentioned this?
FlyBackOU812
Well-Known Member
There is... its a little adapter called charge blocker. Let me see if I can find that link
FlyBackOU812
Well-Known Member
Thats a screenshot I got of it last time someone brought it up. Look up charge blocker on you tube
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Interesting I saw that too. Just using an old droid phone rooted with battery limiter app. Works a treat.
We had brought up rooted phones and modules blocking charge, if not in this topic then in others.
Not all of us are willing to root our phones. I used to do it, but that then messes up getting phone system updates without having to wipe the phone. Changing the bootloader alone can cause an OTA update to fail.
Those charge blockers seem to do nothing more than cut off one or both of the power leads. Not all Androids will tolerate this and still accept a data connection. Probably most won't.
Not all of us are willing to root our phones. I used to do it, but that then messes up getting phone system updates without having to wipe the phone. Changing the bootloader alone can cause an OTA update to fail.
Those charge blockers seem to do nothing more than cut off one or both of the power leads. Not all Androids will tolerate this and still accept a data connection. Probably most won't.
Agree. Rooting the phone isn't a good thing and shouldn't be done. Especially if you use the phone for personal stuff like banking. All UK based banks block rooted phones and most seem on the ball to detect hidden root.
Thankfully I will just use this spare phone for the fly app and that's it.
It's the only thing I'm disappointed about with my DJI drone...so far.
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One thing that could work safely (I still believe CareyL's solution is risky) is cut the power leads from the RC to the Android, and feed an external power source limited to 500mA.
They have considered it. But it's not their problem.
Code of connection for the interface is all controlled and mandated by the Android.
Although it is not a hardware issue thankfully. So my rooted old phone with is a oneplus 5, which is supported by DJi now doesn't charge unless I want it to.
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