The links others have posted will pretty much cover everything you need to know, but here are a few tips and a pointer on how to approach them.
First, you mentioned Ohm's law. I believe the Predator is a regulated mod. Ohm's law applies to mech mods, so you don't need to worry about it. What you do need to worry about is how to calculate your amp draw on a regulated mod, and this post on Mooch's blog will explain that:
Calculating battery current draw for a regulated mod | E-Cigarette Forum
As you can see, the amps you need will depend on what wattage you're vaping at. Once you figure that out, you can select a recommended battery from the chart
@Coastal Cowboy posted. The chart is updated periodically, and you can always find the latest version here (Mooch's blog again):
Mooch's Recommended Batteries | E-Cigarette Forum
One thing you might notice is that even though your mod says it can provide 228 watts, there aren't any batteries that will allow it to do so safely. It's a serious problem in the vaping world.
Another thing you'll notice if you review the chart is that there's a trade-off between CDR and mAh.
CDR - Continuous discharge rating - measured in amps, determines what wattage you can vape at
mAh - millamp hours - more or less determines how long a charge will last before you have to recharge
There's a list of reliable vendors at the bottom of the chart. That's important because counterfeit batteries are a big business. Vape shops, and especially Amazon and Ebay, are full of counterfeits. The vendors on the list test for counterfeits. That doesn't guarantee they'll never get taken in, but it's less common and they're known for doing something about it when they find out they've sold them.
You'll see a lot of battery brands in vape shops that aren't on the chart. That's often because they're rewraps. A company buys batteries from one of the manufacturers (Sony, Samsung or LG) and puts their own wrap and specs on the battery. There are two big problems with this:
- The specs are often wildly inaccurate.
- Even if they aren't (at the moment), the battery under the wrap can change at any time. Just because your last Efest worked fine doesn't mean the identically-wrapped battery you buy this time will be the same thing.
About chargers, Xtar, Nitecore and Efest's LUC line are most often recommended as reasonably-priced options with decent performance. You can get fancier chargers, but you won't get much out of them unless you know a bit more about batteries. Note that those three manufacturers also sell batteries - which are rewraps, so avoid them. Their chargers are decent, nonetheless.
Other tips:
- Never carry or store a loose battery. Batteries should always be in your mod, in a case or in your charger (and only in your charger when you're actually charging them). Loose batteries tossed in a pocket are a major contributor to the exploding battery phenomenon.
- Check the wrap regularly (the plastic covering the battery). If it gets damaged or nicked, store the battery carefully away from other batteries and anything metal until you can get it rewrapped. It's pretty easy to rewrap batteries yourself, but if you don't want to try it many vape shops offer a rewrapping service.
- Don't use batteries hot off the charger. Let them rest for an hour or so before putting them in your mod.
- If a battery does something weird - gets hot inexplicably, is physically damaged etc., it's best to recycle it rather than risk problems.
And that's all I can think of at the moment, which is probably a good thing as you've asked for tips, not a novel. Oh, welcome to ECF!