e350coupe
lvl.2
Canada
Offline

Charging our Batteries with Plug In Inverts, attached to car or Deep Cycle Battery.
Our OEM DJI supplied charger is rated as follows
InPut which is how much voltage/amperage is need to operate
100240 volts, Alternating current (AC) which allows it to operate if various countries.
1.4 amps which is usually based on the industry standard of 120 volts.
OutPut
26.3 volts Direct Current (DC)
3.83 amps.
From above we can see that if we use the industry North American standard of 120 Volts then the unit needs 168 watt to supply the rated output.
Based on the standard formula of volts x amps equals watts we then take the output of 26.3 volts x 3.83 amps which equals 100.729 watts or 100 watts.
So the efficiency of this unit is output/input or 100.729/168 equals 59.95% efficiency.
It is possible that the 1.4 amp draw refers to the 100 volt input, however I doubt that as 120 volts is the industry standard, and regardless by using 120 volts, you are on the safe side of your calculations.
Now as for the converter issue, there is sine wave which is what you get at your house, and square wave which is what cheaper inverters use.
Where the one person commented on inverters wrecking the charger it is possible that with a square wave inverter that this would more then likely happen.
If you are going to use an inverter the only use a sine or pure sine wave inverter with a minimum of 200 watt rating. Although it only takes 168 watts to fully power this charger as time goes on the input voltage to the inverter will quickly from from 13.2 to 13.8 DC volts, downwards to 12 volts DC, resulting in a 14% voltage reduction which will translate to an output wattage reduction to the inverter.
As for the 40 amp fuse rating on the inverter, you have to calculate that this amperage is calculated with 12 volts being converted to 120 volts, and you must take into effect the surge rating, which will not apply in this case. However a 200 watt inverter, will give a temporary surge for milliseconds upwards to 400 watts. This 400 watts can be supplied with an input voltage as low as 10 volts, before causing damage to the battery and thus a 40 amp fuse, would be a suitable unit for a 150200 watt inverter.
Now that I have completely bored everyone with this useless information which I cannot forget, I would reccommend a minimum 200 watt sine wave (also known as Pure Sine Wave) inverter with a direct connection to the battery to charge these batteries with the use of the DJI charger.
One other thing you might want to consider is that the inverter is also inefficient in changing the 12 volts DC to 120 volts AC and we should take this into consideration on how we plug this into the car. Most inverters are 8085% efficient thus to supply the 168 watts to the DJI charger they will likely take 200 or so watts powering the inverter.
With the battery off you will likely be using 200 watts/12volts which equals 16.66 amps. 14 gauge wire generally handles 15 amps, and 12 gauge wire handles 20 amps. I generally use 10 gauge yellow fine stranded wire with an inline 20 amp circuit breaker attached directly to the battery terminal. By running this through the firewall in a flexible 1/4" conduit you will have a circuit capable of handling upwards of 360414 watts depending if the engine is running or not. (circuit breaker will need to be updated to 30 amps)
It is possible to get direct 12 volt to 24 volt adapters to charge these batteries but by doing so you will void the warranty, and I would not recommend this.
Hopefully this answers some questions, but please do not use a cheap inverter to charge you 3k plus units. You should expect to pay $80$100 for a full sine inverter rated in the 200 watt range. Beware of things like partial sine wave, square wave or semi Sine wave, what they are really saying is that they are not sine wave conversion of 12 volt DC current to 120 volt alternating current. 
