The impression that it would be a good fit was bolstered by an image of the product on the web sites that looks like the size and shape of the original battery, but which looks nothing like the battery that was delivered.
Whether it was the extra weight, or the battery sliding about in flight that caused it, or just an unhappy coincidence - our drone lost control and dived straight for the nearest wall when we first tried to launch and hover, with the Maxamps battery in place. Result, a broken cross piece and a long wait for replacement parts.
So this instructable will show you how to install the maxamps battery so that it doesn't slip whilst in flight and as a bonus you'll also see my hack repair of the central cross piece using JB Weld -- a stop-gap measure just to get back in the air until Amazon get the replacement parts back in stock. (Must have been a lot of people bought these for Christmas and have broken them already!)
Here is what the MaxAmp ad promised... a nice professionally finished product that looks to be about the right size and shape to be a drop-in replacement for the stock battery,
Step 1: Comparing the Batteries
The stock battery is on the left for a size comparison. The drone's battery compartment is an exact fit for the stock battery, which means that the replacement 'guaranteed fit' battery is narrower, shorter, and therefore slides around under the accelerations of flight.
The replacement is also obviously taller, but surprisingly it does just fit under the hull, which I guess is what justifies the 'guaranteed fit' claim in the ad..
Step 2: Mind the Gap
Step 3: Cut the Foam to Fit the Battery Compartment and the New Battery,,,
Cut the foam to fit between the battery compartment and the new battery,,,
The new battery doesn't fit with the existing velcro strap, so you need to strip your drone down to remove it and fit the replacement strap that came with the battery. Fortunately I had mine stripped down already, to fix the broken central cross piece. I don't remember seeing it mentioned anywhere that you have to strip your drone down to fit the replacement strap. It's quite a chore and requires a toolkit which the manufacturers sell on Amazon.