Nigel_
Captain
Flight distance : 388642 ft
United Kingdom
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Yes, it is possible!
A USB power bank provides 5V, to charge the P4 battery you need 17.5, or between 13 and 16 if you have the car charger. So you either need to convert the 5V into a higher voltage which is possible but not really feasible for the amount of power being consumed, or you need to connect 3 USB power banks in series to get 15V and then use the car charger.
USB power banks typically provide 10 Watts per port, to charge the P4 battery requires 90W, so you will need 9 power banks connected with 3 sets of 3 with each set having 3 connected in parallel and the 3 sets in series.
The P4 high capacity battery holds 89.2 Wh of power, so to give a full charge each of your 9 power banks will need to hold 89.2 / 9 = 10Wh of power, power banks are normally rated in mAh, 10Wh converted to mAh is 2700 mAh.
If you can find a powerbank that has 3 x 2.1A ports then you can connect the 3 ports together in parallel and then connect 3 of those power banks in series. Each power bank then needs a capacity of 2700 x 3 = 8100mAh. There will be a bit of power lost but 3 10,000mAh power banks, each with 3 2.1A outputs + the car charger + a spaghetti of cables + 1 hour charge time should be able to do the job for a single charge.
I recommend buying an extra p4 battery, although it will cost a lot more...
For portable charging, the only really practical way is to use a lead acid caravan battery (deep discharge) with a mains inverter and the normal DJI mains charger, although it does need to be a "pure sine wave" inverter to avoid blowing up the mains charger so still isn't a cheap solution. |
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