My experiences with the DJI Mavic car charger has not been good.
Is 12V enough?
After three outings where my attempts to charge a battery have failed I decided to do a little research. First, it appears the DJI Mavic car charger doesn’t work unless the vehicle is running.
The issue is simple, 12V is just not enough. In my research I saw there was debate about the exact numbers but the bottom line is when a car is running the charging system produces over 13V. This means when the engine is running (the charging system is active) the voltage is slightly higher than the battery by itself.
A Mavic battery pack is 11.7 volts and a typical voltage regulation circuit introduces around a 1 volt drop. If you do the math it is simple. When a car isn’t running you don’t have enough voltage to get past the low-voltage circuit. This is seen as the charger not powering up (led does not light). Start the car and the power led will light up. Mystery explained!
My Prius
I have no control over when the engine runs. Something most people probably don’t know is that a Prius has two batteries and one is a normal car battery. The other is the power pack for the motors in the drive line. When the car is ‘On’ the electrical systems are connected. So, even though the engine may not be running the voltage is a little higher. When the car is ‘Off’ only the normal car battery is connected. It is just like a normal car in the off position.
So the Prius must be ‘On’ in order to charge a Mavic battery. Since the Prius does not idle I was interested in what a battery charge might require. I found that the car runs 3 or 4 minutes out of every 10 to keep the level in the power pack from being depleted. It appears to be charging but after two hours it had only added a few percent of charge a battery ending at 53%.
It is interesting to note that the dual battery charger I bought won’t work in the Prius at all. It must require a higher voltage than the DJI charger. My guess is the Prius’s power-train voltage is slightly less than the charging system in a normal car since the dual charger does work in the Subaru when it is running.
My Brother’s Chevy
My other experience with the DJI Mavic charger was in a brand new Chevy truck. I had a battery at 1/2 and started the charge as we were driving to the next spot. We were parked when I checked the battery and it was only at 3/4. I disconnected and reconnected the battery to the charger. It acted like it was going to start charging but then just quit.
This experience is why I decided I really needed to look into this further, and the reason I wrote this post.
Summary
If you are going into the field and need to recharge your batteries, make sure it will work. I’m not the only one who has experienced problems.
Recognize that your vehicle will probably need to be running while you are charging, and that a charge will take over two hours.
Hybrid and Electrical vehicles may present their own issues. In the case of my 2005 Prius, it simply has to be ‘On’ but it works incredibly slow so I wouldn’t consider it an option.
The only thing left is to see how fast things charge in the Subaru having pretty much ruled out the Prius completely. Maybe an voltage-inverter but that seems like a lot of conversion.
