P4P+ vehicle charger: 150W, 300W, 500W ?

[ribjig]

Previously, was advised to get 300W, not 150W, as the
former would charge bird + remote faster...

But what about 500W? Too much W?
(most charging would be in Ford Fusion)

For example:
Amazon.com: Buying Choices: SUNGOLDPOWER 500W 12V DC to 110V AC Car Power Inverter Converter Car Cigarette Lighter Modified Sine Wave With USB Port Battery Cables And Clips Built-In Fan (500W)

 

[smiller]

The P4P OEM AC charger draws 1.4 amps max at 120 VAC, or 168 watts, so a 150-watt inverter will be insufficient. It is best to have some headroom (less stress on the inverter) so I would use a 300-watt unit as a minimum. But the capacity of the inverter itself has nothing to do with the charge rate, as long as it is capable of supplying the charger with sufficient power (and it will probably automatically trip out/turn off it it can't) then you're good, and a larger capacity inverter than you need will neither hurt nor help, beyond being physically larger than necessary.

As was discussed in another thread if all you will ever be doing is charging a single battery then you could also get the DJI mobile (12-volt) charger, it has about 10% lower output so slightly longer charge times, but would be simpler/smaller than an inverter and the AC charger. If you want to charge multiple batteries at once though then you would need to go with an appropriately-sized inverter.

 

[ribjig]

Thanks for response.

DJI Online Chat provided this:

battery : DC Output: 17.4 V; 5.17 A; 90 W
controller: Operating Current/Voltage 1.2 [email protected] V

Specifications (DJI's own car charger, only 1 outlet?)
Product Model: C4S90-4
Operating Temperature: 32° to 104° F (0° to 40° C)
DC Input: 12.3-16 V (Sedan); 25-30 V (Coach)
DC Output: 17.4 V; 5.17 A; 90 W
Charging Time*: 1 hr 10 min (Intelligent Flight Battery)
3 hr 20 min (Remote Controller)

So if my car charger has 2 plug outlets like some of these:

300w car charger - Google Search

And I am charging battery & controller at same time,
do I still need no more than 300W? What other factors
DC input output, V, etc. do I need to make sure my
car charger does not go below or above?
(I am NOT electrician, clearly... )

 

[smiller]

If you use the DC charger listed above you will not need an inverter at all, it just plugs into a cigarette light plug directly.

 

[ribjig]

I don't want DJI car charger -- it has only 1 outlet.
Am not electrician, maybe inverter is wrong word...
I want 2 outlet car charger, charge battery+controller same time.
Any advice on if 300W enough for both, other specifications required?

 

[smiller]

Both the DJI AC and DC chargers have two outputs, one for a battery and the other for the controller.

 

[ribjig]

Doh. Just realized don't need 2 outlet car charger.
Just one outlet for regular P4P+ charger.
Do I really want to pay $62 for DJI's own car charger?
One outlet 300W car chargers are under $20...

 

[smiller]

Do I really want to pay $62 for DJI's own car charger?
One outlet 300W car chargers are under $20...

In my experience low-cost inverters often aren't very reliable so if you only need to charge one battery (plus controller) for simplicity's sake I'd just go with the DJI DC charger. YMMV.

 

[Onajourney]

You need to be aware of the maximum amperage on cig lighter outlet. Most are only 10 amps which equals about 120 watts. So if you plug say a 300W inverter and exceed 120 watt draw, you are more than likely going to blow the fuse. This is probably why the DJI charger has reduced wattage. The larger inverters are great for powering all kinds of stuff but they need to be wired directly to the battery with the correct sized conductors. BTW...It is not recommended to charger both RC and AC because it can overload the charger and may cause overheating risk.

 

[DanMan32]

Charger wattage does affect intelligent battery charge time. At least it does for the P3. The battery seems to sense how much current it can draw from the charger and adjusts accordingly.
You have to be careful about calculating AC power consumption based on anp draw. That's peak amps and not necessarily constant since those are switching power supplies. They draw spikes of current to feed capacitors, inductors and/or transformers but there's a current limiter to prevent too much of a current spike.
Go by the output wattage and current/voltage instead.

Sent from my HTC 10 using PhantomPilots mobile app

 

[smiller]

Charger wattage does affect intelligent battery charge time. At least it does for the P3. The battery seems to sense how much current it can draw from the charger and adjusts accordingly.
You have to be careful about calculating AC power consumption based on anp draw. That's peak amps and not necessarily constant since those are switching power supplies. They draw spikes of current to feed capacitors, inductors and/or transformers but there's a current limiter to prevent too much of a current spike.

Well, kinda-sorta and not kinda-sorta. The way it works is this (for the AC charger with inverter):

The DJI charger can supply a total of 100 watts to the battery (and controller if connected), and draws 168 watts from the AC input (since efficiency is never 100%.) If the inverter supplies the necessary power to the AC input of the charger then the charger will work at full output, and if the inverter cannot supply enough power to the charger then voltage will droop and it will probably shut down (so you need an inverter that can supply more than 168 watts.) If the inverter has the capacity to supply more than the needed power to the charger that's great, but it will not affect the output of the charger which is always going to be 100 watts max.

On the battery side, the BMS (battery management system) circuitry inside the battery is looking for a proper charge voltage (17.4 volts) from the charger, and will draw power up to the maximum it is designed to deliver to the batteries. If the BMS wants 100 watts maximum (as an example) it doesn't matter if the charger can supply 500 watts, all that will be drawn is 100 watts. As long as the available power is sufficient the charge current is determined by the BMS circuitry, not the charger output.

Lastly, the input current of a switching supply is not going to show any variance due to capacitive charging and discharging, etc. as this occurs at a very fast rate (hundreds to thousand of hz) and will not be any kind of factor the user needs to think about.

When using the DJI DC charger, there is a DC-DC converter that steps the voltage up from 12 volts to 17 volts. The circuitry is similar to a switching power supply but of course there is no need for the inverter portion because there is no AC output.

 

[DanMan32]

You are assuming on the AC side a constant draw of 1.4A. That is not the case with switching power supplies. They pulse their draw so you are not drawing 168 watts. If they were, you'd be talking about a 68% efficiency which is horrible. The current draw is probably averaging a 68% duty cycle, which actually could represent the RMS average of the 60hz sine wave at a peak of 1.6A.

Sent from my HTC 10 using PhantomPilots mobile app

 

[smiller]

You are assuming on the AC side a constant draw of 1.4A. That is not the case with switching power supplies. They pulse their draw so you are not drawing 168 watts. If they were, you'd be talking about a 68% efficiency which is horrible. The current draw is probably averaging a 68% duty cycle, which actually could represent the RMS average of the 60hz sine wave at a peak of 1.6A.

But none of that has any practical application for a non-technical person simply trying to figure out what products to use. They are better off not worrying about RMS values and such and simply using the placarded specs on the device, even if imperfect in an engineering sense.

 

[DanMan32]

As for the battery, you are correct there will be a maximum wattage it will use, but it can work with a lower wattage power supply. Recall that there are two AC chargers for the P3. One is 54W which takes about 90 minutes to charge a P3 battery, the other is 100w which can charge a P3 battery in about 45 minutes.

Modern DC-DC power supplies Are a type of switching supply, taking advantage of an inductor's ability to generate a short burst of high voltage when the current through it collapses.

Yes, switching supplies run at high frequencies, but they still have a duty cycle: a certain percentage of time drawing current, and a percentage of time not drawing current.
Let's assume a hypothetical 50% duty cycle, peak current 1.5A, 100v. Going purely by VxA to calculate watts, you'd assume 140w but since the current is only being drawn half the time, even it is 10 thousand times a second, it still is only drawing 70 watts and that's only considering it as a DC circuit,all on, all off, no issue with phase shift in current to voltage. With AC, you may have a current phase shift to voltage. The specs only gave you the peak current and expected RMS voltage.

Sent from my HTC 10 using PhantomPilots mobile app

 

[Ddvos]

You need a pure sine wave converter otherwise you will probably demolish your phantom battery.

 

[smiller]

You need a pure sine wave converter otherwise you will probably demolish your phantom battery.

A pure sine wave inverter is a better choice for some types of loads but you usually do not need a pure sine wave converter when powering switching power supplies (like the DJI charger), they work fine with MSW (modified sine wave.) When powered by a MSW inverter the DC output of my DJI charger shows no problems at all when viewed on a scope. The same would probably be true for the multi-chargers since they use switching power supplies as well (actually most everything does these days, transformers are almost gone.)

If you will be using the inverter for other purposes as well then you might want to invest in a pure sine wave unit (which cost 2-3x as much), but for use with common switching power supplies and chargers it isn't really necessary.

 

[DroneOnNDP]

In my experience low-cost inverters often aren't very reliable so if you only need to charge one battery (plus controller) for simplicity's sake I'd just go with the DJI DC charger. YMMV.

Yeah totes. To save a few bucks to go aftermarket on lots of accessory gear it's easy to spend more time (which is also $) on average researching and posting in forums to get advice rather than just going with an A1 product designed to work in tandem and under warranty with your expensive gear.