Reddit reviews 3 Pack -12V Water-resistant Add-A-Circuit Blade Type Inline Fuse holder with Cap16 Gauge (Larger)

Others have covered understanding current draw and battery capacity. I'll add a couple more things:

1. Install a fuse somewhere between the battery and the radio. Out in the elements, shorts from rain/snow/moisture can be more of an issue. You can splice something like this fuse holder inline with the battery: https://www.amazon.com/dp/B018W2T7XS/ref=cm_sw_r_cp_api_T7nuyb1MN9FYG A 100 watt rig might need a higher gauge wire so keep that in mind.
   
   
2. Consider installing connectors that don't let you reverse polarity. After a long hike, it's easy to accidentally plug things in backwards. Anderson Powerpoles fit the bill. You'll need a crimper.
   
   
3. An IC-7300 is way too heavy for SOTA work! It's 9.2 pounds, and after budgeting another 5 pounds for a battery, dipole, telescoping mast, mic, some paracord, and another 5 pounds for a couple liters of water and food, and you're up to 20 pounds. That's a heavy load for a day hike, and forget about taking that backpacking. Not only that, you'll spend the entire time worrying about damaging your $1300 rig and its fragile display. I run a relatively light FT-817 for SOTA and I can't wait to learn CW and ditch it for a lighter CW only rig.
   
   Here's my 5 amp hour LiPo for my FT-817 with fuse and powerpoles. https://imgur.com/a/OWpJQ

Well, I think the cleanest way (not messing with factory wiring) is to either add the cable directly to the battery, or to get the ground from the factory ground point, and the positive from the positive solenoid cable. The latter way is the most nice (otherwise you have a bunch of connections on the battery).


There should be two wires on the battery, a positive and a negative (sometimes there are two positive, but rare on modern bikes unless someone already messed with the wiring). Follow the thickest positive cable, it will go to a solenoid like this. First of course remove the battery from the bike (to avoid any shorts while messing with the wiring). Then unscrew that cable which goes directly from the positive battery to the solenoid, on the solenoid end. Now you need to get an eye wiring connector on the cable of that fuse box (most likely with a 6mm or 8mm hole, you can find them at any electrical store or any electrician...), and add it on the solenoid (besides the factory thick wire coming to it, and perhaps there are even other factory wires on there...). Also use some heat shrink tubing on the crimped eye to insulate and make it look clean (I'd also suggest you use as much wire sleeving as possible - either pvc or braided or just heat shrink tubing - that makes the wiring job look really nice and safer, you can also use insulation tape but that's a bit less professional). That's it, you have the fuse block wired to a good positive battery connection. For the negative, also follow the thick negative wire from the battery, it usually goes to the frame or an engine mount - unscrew it there, and add another wire with the eye connector on. Insulation isn't important for ground wires, but it still looks a lot nicer if you use it.