Dead Battery
 

CX 5 had a totally dead Battery 2000K on it 2015

I'm hearing about a few of these issues... Is it becoming that common?

Not a common problem based on the number of CX5's coming thru my workshop.
Yes more battery problems than any other Mazda model.
New technology always has teething problems, plus they are voltage sensitive. Also people need to learn how to look after their new vehicle, ie be wary of adding aftermarket accessories and always lock the vehicle with the remote when not in use.

And ALWAYS check to make sure your interior lights are off. They are hard to see through tinted windows (especially if garage lights are on) and the battery in the CX5 is either a real WIMP or else the car has a lot of hidden power drain when just setting.

I'm hoping that Optima will be making an aftermarket replacement (Yellow Top AGM). They are the BEST. ;)

No they are not the best!
the Optima YellowTop car battery has less cold-weather punch than the other best-reviewed brands in this size range at 750 cold cranking amps (CCA). With the cylindrical design, the Optima battery freezes faster and will not start in very cold conditions. I know i've had one. Odyssey AGM Batteries have 15% more plates than Optima in the same space. the design of the flat plates allows more plates to be packed into the battery avoiding the “dead space” area between cylinders in the “six-pack” design. This means there is 15% more surface plate area which means more power. I believe the dead area between spiral cells on the OPtima is a problem when it comes to the cold. As a matter of fact Optima is only rated for -30 degrees, and the Odyssey AGM is rated for -40 degrees! I know this because I know one of the dealers and I also had a yellow top that would not start in winter!

OPTIMA SC34DU 12V.
Capacity 55AH. Length 10". Width 6.875". Height 7.813".
Weight 43.5 lbs. Cold Cranking Amps 750A
Reserve 120 .

Odyssey 34-PC1500
Length 10.85 Width 6.76 Height: 7.82
CCA 880, Reserve 135

http://www.odysseybattery.ca/images/...ll_battery.jpg

Technology is changing and Optima is falling behind.
Here is the best battery, and they won a SEMA award (double check for application for your vehicle):

http://www.braillebattery.com/index....al_media_award

With 947 Pulse Cranking Amps the battery provides the performance to replace batteries with up to 800CCA ratings.
The Braille GU1R is a battery that weights only 6 lbs and can start a V8. This battery is designed to replace the stock original battery while saving at least 30 lbs.
Length: 7.68” / 195 mm
Width: 5.13” / 130 mm
Height: 7.13” / 182 mm

http://www.braillebattery.com/images...rSEMAaward.jpg

Be careful when replacing a battery in a sky active vehicle, the replacement battery must be compatable with the I-stop system.