I believe these are constructed similar to the Optima. The direct Optima application is the YellowTop H6 model. The prices are similar between the Optima and X2Power. The key is finding a sealed (non-venting) battery for the PMC. Note the PMC uses the same battery (for the same model year) as the 2.4L Jeep Renegade.
It's an X2Power Premium AGM Group 48 Car & Truck battery I bought from Batteries Plus Bulbs. It was an easy drop in with no issues though the stock cable clamps/connectors are just a bit cumbersome to hook up. Look for Batteries + Bulbs online or maybe for something cheaper/better along the same line. I'd guess (hope) that FCA has changed to better stuff by now as well!
I was initially looking to go with Optima as I've used them in other vehicles with great success but they are odd sized and I wasn't confident with fitment so I went with a more common/standard AGM type. I feel investing in a good (albeit expensive) battery is a worthwhile investment having lived in Colorado cold and Arizona heat over the years! Seems people will shell out for premium oil/filters and spark plugs but cheap out on batteries!