Upgraded alternator options
JK Enthusiast
Joined: Nov 2015
Posts: 471
Likes: 19
From: Phoenix, AZ
https://www.waytekwire.com/item/7705...yABEgKyg_D_BwE
I'm running a pair of blue tops, which I just replaced after about 3 years of service. I have the primary battery running the factory connections, along with a cable to the isolator. Once the voltage comes up in the primary, the solenoid closes and connects the secondary battery to the charging system.
The secondary battery carries the brunt of the load on my Jeep. The sPod, which covers the lights, compressor, and lockers, the race radio, the fridge, and pretty much every other option that isn't part of the factory Jeep setup. When the charging system isn't running, the solenoid opens and the batteries run as separate systems. I can run the secondary battery dead and still have full voltage on the primary.
There is also a wire that you can use to manually tie the batteries together, which is a great feature. I was out shooting a commercial for KC in the middle of the desert, obviously at night, when my primary battery decided to shit the bed. Typical AZ thing where the battery is fine one minute and dead the next. Tied the batteries together using the solenoid and off we went. New batteries were picked up and installed the next day.
Having a second battery is a no brainer, and I'm not talking about one bouncing around in the cargo area that you have to change out on the trail. For that kind of situation, I've got a phone charger battery type setup that will also jump a vehicle. This is handy to have, as long as you remember to keep it charged after using it:
http://www.rockfordfosgate.com/products/details/rfc-350
Last edited by jordy; Aug 7, 2017 at 07:04 AM.
JK Enthusiast
Joined: Dec 2007
Posts: 112
Likes: 0
From: Southern Arizona
The factory wire connected to the alternator is either an 8 or 10 AWG wire. I'm going by looks on AWG size, I haven't looked it up. Ronjenx seems to know how to look up the exact numbers. 
According to this chart, Max current capacity of copper wire.
https://www.powerstream.com/Wire_Size.htm
8AWG= 63 amps
10AWG=55 amps
I added 4 AWG to the existing wiring.
4AWG= 133 amps.
133amps + 55 amps (min using 10AWG)= 188 amps
And you said the alternator is 160amps?
The math makes sense to me.
According to this chart, Max current capacity of copper wire.
https://www.powerstream.com/Wire_Size.htm
8AWG= 63 amps
10AWG=55 amps
I added 4 AWG to the existing wiring.
4AWG= 133 amps.
133amps + 55 amps (min using 10AWG)= 188 amps
And you said the alternator is 160amps?
The math makes sense to me.
Great information, thank you! I have to replace my failing alternator and decided to go with the Mean Green 220 amp upgrade. With this I was looking to do the Big 3 cable upgrade as well. My question is, based on the chart you provided, with a 220 amp alternator I should use 2 gauge wire to add to the existing setup. This will bring the numbers up to 236 for the lines. Now I'd want to add a fuse correct? My thought was to put an Installbay inline fuse but have no clue on which one. They come in a wide range of amps to include 200A and 250A. Any advice will help. Thank you.