Phantom 4 Pro charger power consumption?

[Ben01]

Hi everyone,

I’m looking at purchasing a portable lithium power pack to charge my drone batteries and RC while travelling.

I’m completely illiterate when it comes to all things electrical so I was just wondering what sort of power does the genuine dji car charger use? My car charger is the single battery charging unit for p4p - does not charge two batteries at once.

The unit I’m looking at is a 21.5ah (see pic) which also has an inverter for AC use but I have no idea if it would be better to charge with that or via the 12v socket. I have both standard AC & car charger.

Just wondering if anyone could maybe tell me roughly how many battery charges I’d get out of this?

Many thanks for any advice.

 

[DoomMeister]

Standard P4Pro batteries are rated at 5870mAh (5.870Ah). Typical use will take them to half that amount so you will have to add roughly 3000mAh (3Ah) to fully recharge. This unit could feasibly recharge 6 to 7 batteries. The AC outlet would likely charge a pack faster, but the 12V outlet may be more efficient (less loss to charging units).

 

[tribar]

Hi everyone,

I’m looking at purchasing a portable lithium power pack to charge my drone batteries and RC while travelling.

I’m completely illiterate when it comes to all things electrical so I was just wondering what sort of power does the genuine dji car charger use? My car charger is the single battery charging unit for p4p - does not charge two batteries at once.

The unit I’m looking at is a 21.5ah (see pic) which also has an inverter for AC use but I have no idea if it would be better to charge with that or via the 12v socket. I have both standard AC & car charger.

Just wondering if anyone could maybe tell me roughly how many battery charges I’d get out of this?

Many thanks for any advice.

You can't compare Ah without taking in account the Voltage.
That's why you have to use Energy Density in Wh (Watt hours, equals V x Ah)

The iTECHWORLD PS300 has an energy density of 276Wh.
A P4P battery has an energy density of 89Wh (15.1V x 5.87Ah).
The maximum usable energie from any battery is about 80%.
The common efficiency of battery driven charges is 75%.

Conclusion:
PS300: 276Wh x 80% x 75% = 166Wh usable.
P4P: 89Wh x 80% (when empty) = 71Wh to replanish.
The PS300 can charge: 166 / 71 = 2.3 fully drained P4P batteries.

You can do the same calculations for your car batterie, where the energy density of your car battery equals V x Ah (for instance 12V x 50Ah = 600Wh).

 

[Harleydude]

It looks like your questions were answered in the comments. I'll just add that the 12v cigarette lighter charger is basically junk. I don't remember exactly how much current the cigarette lighter sources, but I believe it was less than an amp (12 watts)...which makes it essentially useless. Charging just 1 battery from 30% to full takes like an hour. Ridiculous.

If one is looking for charging efficiency off of a car battery, one must eliminate the wasteful DC->AC / AC->DC conversions. Your car is a DC device, as is your drone batteries. It is extremely wasteful to convert your car's DC to AC via a converter, and then use an AC charger to charge your Phantom's DC batteries. So what I did was build a simple DC voltage regulator that steps up my car's 12v battery to whatever voltage I need for charging Phantom, Mavic or Inspire 1 batteries. Remember; your car battery is designed to source hundreds of amps (advertised as "cold cranking amps"). I take full advantage of my car battery's strength and charge multiple batteries at the same time.

I can adjust the charging rate, which I limit to 6 Amps, but more often than not limit to lower rates closer to 3 or 4 Amps.

I rarely allow my batteries to drain past 30%, so I can usually charge 6-10 batteries before my car battery's voltage drops too low and I need to start the vehicle.

The best thing is that the smart batteries are self regulating, so they draw less current as they approach a full charge.

While not idiot-proof or even idiot-resistant, this system allows me to fly jobs all day long without the need for DJI chargers or any infrastructure (AC outlets). But one must know what one is doing or one could start a fire or create a dead short situation, which is never good.

D

 

[tribar]

a simple DC voltage regulator that steps up my car's 12v battery to whatever voltage I need for charging Phantom, Mavic or Inspire 1 batteries.

That's exactly what his car charger is doing (NO DC-AC conversion).

don't remember exactly how much current the cigarette lighter sources, but I believe it was less than an amp (12 watts)

A KIA Picanto has a 15A fuse for each the 12V Power Outlet & Cigarette Lighter (2 x 180W).

 

[Harleydude]

That's exactly what his car charger is doing (NO DC-AC conversion).

Correct. But, as I pointed out, it doesn't source enough current.

A KIA Picanto has a 15A fuse for each the 12V Power Outlet & Cigarette Lighter (2 x 180W).

While you'll get no argument from me regarding your fuse size, if you check the charger you will find that it doesn't draw nearly that much current. As I pointed out, you will find that the charger pulls about an Amp. I assume this may be due to "continuous use" limitations of the cigarette lighter (power jack), which was originally designed for high-amperage use for very short periods of time.

Worth noting, 15 amps requires #14 copper wire (#12 aluminum wire). Dollars to doughnuts the wiring going to that power jack/port is not that robust. It would be interesting to find out.

UPDATE: Seems the cigarette plug charger I have pulls TWO Amps (24 Watts). Still, way underpowered IMHO.

D

 

[tribar]

But, as I pointed out, it doesn't source enough current.

The original DJI car charger for the Phantom 4 is a 90W charger (5A).

I assume this may be due to "continuous use" limitations of the cigarette lighter (power jack)

That's nonsense.
There's is NO circuit between the car battery and the power plug/cigarette lighter plug to limit the current other than a fuse.
How else could you connect all sorts of equipment to it, like Lights, airpumps, refrigurators, coffee makers, and so on.

 

[Harleydude]

The original DJI car charger for the Phantom 4 is a 90W charger (5A).

12v x 5=60W
15v x 5=85W

The math of that assertion doesn't work out. At 5A, at BEST is between 70 and 75 watts. Any automotive system operating over 14.4v for very long is in trouble.

That's nonsense.
There's is NO circuit between the car battery and the power plug/cigarette lighter plug to limit the current other than a fuse.

I didn't mean that there was a literal current limiter in the circuit. I meant that there is a limit in the spec (power vs *continuous* power).

How else could you connect all sorts of equipment to it, like Lights, airpumps, refrigurators, coffee makers, and so on.

All of the devices you mentioned draw power for short periods of time (under 10 minutes). Even then, I would have to see the spec. Dollars to doughnuts none of these items draw 15A of current. I would honestly be shocked if any of them drew 10A. This is probably due to unreliable voltage from the car. As I'm sure you're well aware, Watts is the only constant. So, as voltage drops, Amperage increases. As voltage drops to under 11 volts, you can see how this would increase the Amperage. This may be a reason for the low Amperage ratings.

Conversely, drone battery chargers draw current for long periods of time. And because of the voltage conversions, one really must talk in Watts.

I think you will agree that 180 Watts is a typical "quick charge" for any drone battery. A standard charge is about 100 Watts. If you check your P4P AC charger's secondary voltage, you will see it operates @ 17.5VDC and charges at a rate of 5.7A, which equals 99.75 Watts. Hence, the part number "P4PC100." The problem is that no car runs @ 17.5VDC. At 14.4VDC (running vehicle), 100w equals almost 7 amps. WithOUT the vehicle running (12.5VDC for a resting battery with no draw) this comes out to almost 8 Amps. Even higher Amperage when voltage drops due to load. So this begs the question, "If cigarette ports are able to source 15A continuously, why are the P4P/Mavic/Inspire chargers rated for a measly 5A?"

I can't tell you exactly WHY drone manufacturers limit their car (cigarette / power port) chargers to 5A. But the fact remains that they do. I can only assume that the drone manufacturers are aware of automotive cigarette lighter port limitations that you and I are not (like CONTINUOUS power ratings based on worse-case-voltage-scenarios not published in the standard automotive nomenclature). The math flushes this out.

Discuss.

D