Having seen @My-Mavic-My-Rules’s dual battery mod, my curiosity got the better of me…
And as if by some kind of omen, our friend digdat0 comes along and does a 50 minute step by step tutorial on the very subject 
Anyone else tempted?
@My-Mavic-My-Rules any tips or advice to add? Good UK source of batteries and connectors perhaps? (And a charger?)
Curious too, how does GO4 react to this? Does it magically know and auto-adapt?
Not watched the video but I’d think the mavic wouldn’t be able to read the cell voltages on other battery.
I’d probably consider something like this when Mavic wasn’t my main bird.
Steve aka Digidat does the best YT how to vids, it was a bit of a pain for me as I’m pretty crap at soldering and there ain’t much room in there. I used the smaller xt30 plugs as they are a lot smaller than the xt60’s in Steve’s vid as mine can be flush mounted. I buy my batteries and bits from Hobby King, I think they are in holland? You just have to make sure that the main battery has a tad more voltage than the aux battery’s otherwise the Dji batt will switch off. The Go 4 app will still show the correct voltage.
I’ve been researching this some more today and I’ve found a way to do this mod WITHOUT having to physically open / modify / dremel the Mavic 
Here’s what I think is needed:
This clip, while bloody expensive, means zero physical mods to the MP:
That’s all really!
Entire kit for about £120 quid and it’s plug and play, no permanent mods required.
@My-Mavic-My-Rules any thoughts on those battery sizes vs weight efficiencies that I’ve picked out mate? And LiPO vs LiHV?
Wow that is expensive. Just looks like 2 connectors heatshrinked together with an led for show.
What kind of increase in flight time would you expect with this?
Those multistar are about 240g each.
I’m tempted lol
That is the battery clip adapter(was) dual lock, charger, LiHV batteries I use
I had the top battery clip adapter on my last drone, had good results,I had plenty of 18-19 odd mile round trips. This year I’ve gone direct mod that should give me a little bit more due to a much better amp/volt flow than just the slits touching the terminals on the top mounted one. I glued mine on as removing it a few times wears the slits and becomes a little lose. I also modified mine to sit upright so the battery can sit forward without covering the gps at the back.
You can buy it cheaper from here http://www.uavmods.co.uk/store/products/47495-dji-mavic-pro-power-platinum-adaptor-dual-xt60
They have made the copper strips a little longer so it sits more towards the front to be easier to plug a top mounted battery in without the battery sitting over the gps at the back, BUT I’m not sure it’s far enough as I’ve never tried their battery clip. If you mount the batteries on the side with a top clip, from my experience it would be a pain keeping the wires away from the props.
Here’s my modded clip and setup from last year
Rich, been reading up on it a little. Some people stating only 5-6 minutes extra battery life due to the added weight.
Flying at standard speed (22mph) uses same power as sport mode without the mod.
Not sure it’s worth it for me personally.
It can’t be a total coincidence that most quadcopters have 20/30 minute flight time.
Few less, fewer more.
I get 40mins flying at a steady 32mph
That’s more like it!
Do you know if the battery clip has diodes or does it just want as a splitter?
No diodes, just works as a splitter
Have you experimented with any other battery sizes?
I’m just thinking along the lines of highest power density and diminished returns.
My warranty for Mavics not up till September or I’d probably went same route as you.
Think I’m going to order the clip.
Yeah I think power vs weight is going to be key here.
Finding the right power to weight ratio could get expensive by trial and error. I wonder if there’s a mathematical formula to work out the optimum sizes?
Found some more pics.
This is the longer clip that @My-Mavic-My-Rules was referring to:
The green LED comes on when it’s ready for you to connect the batteries, which is handy I guess.
I also found a cool 3D printed bracket for holding two batteries in place:
I’m still undecided on this mod…
Again, power to weight is playing on my mind. There’s an optimum milliamp/hour power to grams weight ratio for sure.
Can’t see the MP battery LEDs with that bracket. 
I don’t think you need to?
You’ll be flying 
GO4 will give you the battery details you need while in the air (and on the ground too)
The bracket is £30 odd quid, think I’ll stick with Velcro 
Powerful batteries! I weigh 85kg! 
Rich, you read this yet? Mavic Battery Mod — Maxx UAV
Seems they recommend a single 3000mAh or a couple of 1500s.
I’m not convinced either of those two recommendations are the ideal setup @callum
I have nothing to base these suspicions on, I’m just a bit dubious 
@My-Mavic-My-Rules what battery size(s) are you running currently Mick?
