Reddit reviews Nilight 120 Pcs/60 Pairs Quick Splice Wire Terminals T-Tap Self-stripping with Nylon Fully Insulated Male Quick Disconnects Kit, 2 Years Warranty

I installed this one on my beater truck. Looks to be available for under $100. Also there's a youtube video on how to install it. Just wire it into one of the backup lights (I used a T-Tap) and it will only come on when you put it in reverse.

I've heard those called Vampire taps before. It doesn't seem right to call this a "brute force" mod. It's quite simple, elegant, and non-destructive.

EDIT

I guess vampire tap just refers to the old 10BaseT networking thing. Found these "T-taps" on amazon:

https://www.amazon.com/Nilight-Terminals-Self-stripping-Insulated-Disconnects/dp/B07CP987BN

1. Yes you can. Make sure you get a 120 volt switch. Your common options are a 12 volt switch, 24 volt switch or 120 volt switch. Since you're panels will be operating around 60 volts, you just use the next one up, which is 120 volts.
   
   
2. Grounding one is fine.
   
   
3. I don't see a question 3....
   
   
4. This one is a judgement call, and maybe someone with more battery knowledge can chime in. When completely dead, the battery will take as much current as the alternator will supply to charge. As it gets more charged the current will drop significantly until at some point it's completely full and drawing very little current. I've seen batteries before in flatbed trailers used for winches that charge on the 7 pin trailer plug with 12 gauge wire. That wire gets very hot when the battery is completely dead, but I've never seen one catch fire or melt either. Since it's not running 150 amps constantly, you get to be the judge on how thick this wire needs to be. It doesn't need to be 00, but I personally wouldn't go smaller than 8 awg. The online wire calculations assume maximum current "continuous load", which means at least 3 hours of maximum current, that's where the 00 gauge comes from, supporting 3 hours at 150 amps. If you ran 150 amps to your batteries for 3 hours, they would explode. I've yet to find a simple wire calculator that does peak loads followed by lower loads, so that's where judgment comes in. A slow blow 50 amp fuse would probably be enough protection there since the amount of time you'll be drawing more than that will be short before the amps taper off. I believe the isolator in my van is all wired with 6 or 8 gauge wire from the factory.
   
   
5. Order doesn't matter.
   
   
6. https://www.do-it-yourself-help.com/receptacle-outlet-wiring-diagrams.html
   
   The other option is to just plug in a power strip if you don't need permanent installed outlets. If you are going to permanently install the outlets the wiring should be SJO cable to circuit breaker, circuit breaker to all outlets.
   
   https://rvpartsexpress.com/product/20-amp-gfci-stand-alone-circuit-breaker/
   
   7.https://www.amazon.com/Nilight-Terminals-Self-stripping-Insulated-Disconnects/dp/B07CP987BN/
   
   T-taps and some spade connectors would be the easiest way, otherwise it'll be a lot of cutting and soldering. If you go with t taps you can mix the colors of the connectors. It'll likely be a yellow tap on the 12 gauge trunk line, and the LED positive will get a red spade connector to plug into the yellow tap. The spades themselves are all the same size, so use the right color connector for each individual wire.
   
   
   
   Other comments: the wires coming from the charge controller to batteries only needs to support 40 amps. They can be 8 gauge and fused at 40 amps, not 150. Your wire from battery to fuse block can be 8 gauge as well. I only see 25 amps of accessories in the block, and you'll likely never run all of them at once. So an 8 gauge supply and ground line with a 40 or 50 amp inline fuse will give you plenty of room to add more accessories later while being safe.
   
   Edit: make sure you buy twisted strand copper wiring and not aluminum clad or solid core. Best spot for the thicker wiring is car audio stores or search amazon for stereo amp installation kits. If you go to home Depot for 0 gauge wire it'll be rigid and hard to work with, the car stereo wiring is super flexible.
   
   Edit 2: you may want to consider adding a battery management system after the isolator. They make many variations, some that include the isolator function as well. Some allow you to program a maximum current for charging the lifepo4, which will make it easier to judge wire size for that run. The big benefit though is that a standard car alternator will only charge lithium batteries about 75% because it's regulated to about 14.2 volts. That's what the lead acid battery expects for charging. The lithium needs 14.7 or more to charge fully. So adding the bms will allow the lithiums to fully charge while driving, otherwise you'll have to rely on the solar for the last 25% of the charge. Just make sure to program the charge controller for lithium batteries.

https://www.amazon.com/dp/B07CP987BN/ref=cm_sw_r_cp_apa_i_SzyZDbW15NCS6

Are these the correct ones? I just want to make sure before I buy. I might look on eBay to see if I can just get a couple since I don't need so much lol

Accessory wire is the 12v+ that gets current when you put your car key in the ignition and turn it (or, if you have wireless keys, just when ever the radio can play, but not the engine) (accessory has 12v+ with the engine running)

Basically, if you can turn your radio on, the accessory wire has current.

You want to use this wire, because the lights will turn off automatically when you get out the car.

You can tap into the wire using a t-tap like this

Nilight 120 Pcs/60 Pairs Quick Splice Wire Terminals T-Tap Self-stripping with Nylon Fully Insulated Male Quick Disconnects Kit, 2 Years Warranty https://www.amazon.com/dp/B07CP987BN/ref=cm_sw_r_cp_apa_i_DXa2Cb03G4FAR