Portable field power

spiderpig · Jan 25, 2017

So since I've gotten my phantom 3 and now Mavic, I've been looking for a portablish way to be able to recharge my batteries after flights. Some fields your not close to your car so can't rely on the car charger (even though I've had mostly misses with the Mavic one). So I've ventured into looking for a portable 12 volt battery type machine to recharge my batteries. After a couple misses I think I finally found one that will work. I did field test it with a friend at the last fly in we had (he had just bought it, and I bought one right after we left). So I know it works on the field...but I wanted to see how many batteries it could charge on a full charge. So here's the results:

Overall....worked great and would recommend it. It's a big on the heavy side, but at least you can stay in the field longer.

KiterTodd · Jan 25, 2017

I agree with your assessment that it is kind of heavy to bring in the field. It costs about as much as a Mavic battery ($89 vs. $82) so I'd just buy 1 extra battery...maybe splurge and get two since you'd have less weight to pack on your trip.

I suspect you may have some inefficiencies in that link with the blue charging hub you have in there. It's possible that hub was not designed to be energy efficient (didn't need to be) so it burns off extra juice with resistance to get to the correct charging voltage. Yes, I'm talking out my backside a bit, but if that charger/jumper/thing has a large enough battery to jump start a car, I'd think you should be able to charge more than two Mavic batteries. Be curious to see a comparison using the stock Mavic charger or their 4 battery hub.

Of course you can go solar, but I suspect a field solar panel that could charge a Mavic would either take a long time or be very costly. I'm going to look into solar, though, for upcoming kayak trips where I can't bring a heavy option with me.

In any case, thanks for throwing the video together and sharing it! It was a great reminder that we have some options out there to get more flights than we do batteries. Thumbswayup

F6Rider · Jan 26, 2017

Now THAT is a good idea. I have a 12CDC battery jump start unit similar to this one, I will top it off and see if it will work with the 12V DJI charger and Hub. Don't need it at this time but it might be an option at a field where I have to park the truck a ways away.

lucky4meman · Jan 26, 2017

I bought an Omnicharge last year through Indigogo and finally got it shortly after my Mavic. Thing is perfect for portable power. Has two USB outlets and a regular plug in 3 prong outlet

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Dw911 · Jan 26, 2017

He couldn't have wasted more energy if he tried changing those two batteries so inefficiently in the video

Your better off if you use something like the one in the video, is to not use the AC 110/240 volt, but use the 12 volt DC socket with the mavic pro car charger.
By using the AC socket you are wasting/using valuable energy just to power the inverter.
No energy wasted using the 12 volt DC socket and you will probably charge 4 - 6 mavic batteries from a pack like that as opposed to the 2 he managed

spiderpig · Jan 26, 2017

So awesome discussions. I think there is more testing that will need to be done with AC vs DC power here. But a couple notes:

1) I was able to charge two batteries, controller, and phone in and hour and ten minutes. If I move the USB devices to another portable usb power source, I think I might be able to charge three batteries in that time. But the point is after and hour and ten minutes - I have two charged batteries.
2) I've have mixed results with the DC car charger that came in the fly more combo. During flight days, I've never gotten it to work in my car and I know it was getting power. But I'm willing to test it out to see how long it'll take to charge a battery using this portable power unit.
3) From what I've read the car charge can charge a battery in an hour. So after one hour using the car charger - I only have one battery to use. Even if I used the four charger thing, it still only charges one battery at a time. But from the point of efficiency I might be able to get more power out of the portable unit - SO testing will be done to see how many batteries I could charge using DC vs AC.
4) Most flight days were only in the field about 2-3 hours. So was looking to maximize battery recharging in that time.

Awesome conversation guys....will do more testing!

spiderpig · Jan 27, 2017

Did a second test with DC power...and it is quite more efficient with DC power. But still took an hour to charge one battery. So if you have more time in the field DC is better...if your short on time, AC is the way to go:

Dw911 · Jan 27, 2017

Nice tests, always good to see how different ways pan out in practice, as you say some times you just need fast charging of maybe one or two batteries quickly , other times you may need lots of batteries charging , guess it depends how long your out in the field for flying

spiderpig · Jan 27, 2017

When the weather gets a bit better will do some actual field tests. While temperature haven't been too bad, wind around here is crazy the last couple days. So don't want to risk it.

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KiterTodd · Jan 28, 2017

That's good to know. If that thing can charge up a lot more batteries on DC, that could be the way to go.
Look at it this way...if you have 4 batteries, once you use the first battery put it on the charger....by the time you've gone through the other 3, the "5th" battery will be charged and you can swap in the 6th. If you need more than 5 batteries in a single session... you need more batteries.

And then, when you are done with your flight session, I bet you can charge up 3 more batteries and you'll be set for a fresh start the next day. That's a good weekend!

Dw911 · Jan 28, 2017

spiderpig said:
I've have mixed results with the DC car charger that came in the fly more combo. During flight days, I've never gotten it to work in my car and I know it was getting power.

I've had issues with mine, I unscrewed the silver piece on the end then it worked ok without it, not had time to investigate whether it's a faulty connection inside the plug or that the silver piece was stopping it making a positive connection to the + terminal inside the cars accessory socket, but it didn't look like it was.
Also seems like the car charger may shut off below a certain voltage, as wouldn't work in a car with a low battery - possibly a protection thing to prevent a very
flat battery that's unable to start the vehicle, my car inverters do similar thing -, although again it may be I simply have a faulty mavic car charger.
I'll investigate properly when I have time

spiderpig · Feb 5, 2017

So did some field testing yesterday in 32 degree weather:

In our time there we were able to charge 3 Mavic Pro batteries over AC charger. After two hours the AC power was exhausted, but the unit was at 68% power, so we could have charged up more using DC at that time. But being 32 degrees outside, we didn't stay too long.

SteelFlyer · Feb 5, 2017

I decided not to buy the DJI car charger. Instead bought this inverter from Amazon and use the regular AC charger. Works great.

Amazon.com: Foval 150W Car Power Inverter DC 12V to 110V AC Converter with 3.1A Dual USB Charger: Car Electronics

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skynetN9 · Feb 6, 2017

lucky4meman said:
I bought an Omnicharge last year through Indigogo and finally got it shortly after my Mavic. Thing is perfect for portable power. Has two USB outlets and a regular plug in 3 prong outlet

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I was wondering if you are charging the mavic batteries with the omnia charger. If so how many mah capacity is the charger and how many mavic batteries can you fully charged before having to recharge the omnia ? Thanks

rajun50 · Feb 6, 2017

skynetN9 said:
I was wondering if you are charging the mavic batteries with the omnia charger. If so how many mah capacity is the charger and how many mavic batteries can you fully charged before having to recharge the omnia ? Thanks

The Omni doesn't have enough capacity to charge much more than 1 Mavic battery. People look at the mAh ratings and think that the Omni is a lot larger in capacity, but they aren't considering that the Mavic uses a higher voltage. You can only compare mAh when the batteries share the same voltage. If you look at the Watt Hours of both batteries you'll see that the Omni has only slightly higher capacity than a single Mavic battery.

For the price, you're much better off buying two extra Mavic batteries. The Omni would work just fine for keeping your tablet/phone and controller charged, but don't expect it to be suitable for charging multiple Mavic batteries.

spiderpig · Feb 6, 2017

We charged the battery with the multi charger thing from China. It can charge three Mavic Pro batteries at the same time, and it has two USB ports for charging controller or phones.

joet · Feb 6, 2017

Keep in mind that using a multi-charger with your typical power outlet in a car and an inverter is likely to draw too many amps once you are charging two or three batteries at the same time. Ask me how I know.

I ran an 8 ga fused wire from the battery to a distribution panel in my truck, and have the inverter and multi-charger connected to that. Works great!

As far as powering in the field without benefit of a car goes, well, you're pretty much going to have to lug something akin to a car battery, unfortunately. There's no getting around the power requirements to charge a battery of a given voltage and capacity. Solar: Forget it. You'd need a 100W panel and full sunshine to charge one Mavic battery at around the time it would take an AC charger. You could have the solar panel (re)charging a 12v battery and maximize how many recharges you could get, but that's about the extent of the practical applications here.

If I had to design something for total off-grid Mavic operations, I'd probably go with a 17ah battery, a 100w solar panel to recharge it, and wire multiple cig lighter female plugs to it - one for each car charger I wanted to use simultaneously. 3 seems reasonable for a 3 or 4 battery setup.

That 17ah should be light enough to carry in a shoulder bag with the other components besides the solar panel.

spiderpig · Feb 6, 2017

joet said:
Keep in mind that using a multi-charger with your typical power outlet in a car and an inverter is likely to draw too many amps once you are charging two or three batteries at the same time. Ask me how I know.

I ran an 8 ga fused wire from the battery to a distribution panel in my truck, and have the inverter and multi-charger connected to that. Works great!

As far as powering in the field without benefit of a car goes, well, you're pretty much going to have to lug something akin to a car battery, unfortunately. There's no getting around the power requirements to charge a battery of a given voltage and capacity. Solar: Forget it. You'd need a 100W panel and full sunshine to charge one Mavic battery at around the time it would take an AC charger. You could have the solar panel (re)charging a 12v battery and maximize how many recharges you could get, but that's about the extent of the practical applications here.

If I had to design something for total off-grid Mavic operations, I'd probably go with a 17ah battery, a 100w solar panel to recharge it, and wire multiple cig lighter female plugs to it - one for each car charger I wanted to use simultaneously. 3 seems reasonable for a 3 or 4 battery setup.

That 17ah should be light enough to carry in a shoulder bag with the other components besides the solar panel.

Interesting concept. Is there some instructions to building something like this? I haven't used solar before, but with the summer days a couple month in the future would be a nice project.

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Anthony Viscomi · Feb 6, 2017

spiderpig said:
So did some field testing yesterday in 32 degree weather:

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In our time there we were able to charge 3 Mavic Pro batteries over AC charger. After two hours the AC power was exhausted, but the unit was at 68% power, so we could have charged up more using DC at that time. But being 32 degrees outside, we didn't stay too long.

The DJI Shade mounts to the antennas