Upgraded alternator options
JK Jedi
Joined: Apr 2010
Posts: 4,468
Likes: 221
From: SE Michigan
The last time I had looked into upgrading the alternator it was due to I have 3000 Watt audio system, and my headlights would dim when my dual 12in sub woofers hit and my battery was not fully charging. What I came to realize was that the stock alternator was actually a pretty high output alternator, and upgrade alternator options were minimally higher current upgrades, but definitely not worth justifying the $600-$700 prices to upgrade to them.
I ended up purchasing some 4AWG wire, and wired it in parallel with the existing alternator, Batt Ground, and Batt B+ wires. More commonly known as the Big 3 upgrade. I also purchased an AGM higher CCA marine battery. My battery charges fine, and no more light dimming issues. I also run my 12K winch off of that same setup with no issues. I'm not a big fan of dual battery setups. Takes up too much space, too much costs and complications in battery replacement. I prefer to get a better marine battery, and upgrading the wiring so that it is capable of charging and delivering the additional power draw requirements.
I ended up purchasing some 4AWG wire, and wired it in parallel with the existing alternator, Batt Ground, and Batt B+ wires. More commonly known as the Big 3 upgrade. I also purchased an AGM higher CCA marine battery. My battery charges fine, and no more light dimming issues. I also run my 12K winch off of that same setup with no issues. I'm not a big fan of dual battery setups. Takes up too much space, too much costs and complications in battery replacement. I prefer to get a better marine battery, and upgrading the wiring so that it is capable of charging and delivering the additional power draw requirements.
Last edited by Rednroll; Jul 3, 2017 at 09:38 AM.
Thread Starter
JK Enthusiast
Joined: May 2014
Posts: 265
Likes: 2
From: SoCal
Hmmmmm so you're saying that the wire is to narrow and you get improved performance upgrading? 160 amp alternator with a short run doesn't really seem like the wire needs to be upgraded like that....
JK Jedi
Joined: Apr 2010
Posts: 4,468
Likes: 221
From: SE Michigan
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.
Last edited by Rednroll; Jul 3, 2017 at 11:49 AM.
JK Jedi Master
Joined: Feb 2008
Posts: 12,907
Likes: 185
From: Maine
I would not install a higher capacity alternator without also increasing the size of the wire between it and the battery.
JK Super Freak
Joined: Dec 2009
Posts: 1,695
Likes: 3
From: Texas
The last time I had looked into upgrading the alternator it was due to I have 3000 Watt audio system, and my headlights would dim when my dual 12in sub woofers hit and my battery was not fully charging. What I came to realize was that the stock alternator was actually a pretty high output alternator, and upgrade alternator options were minimally higher current upgrades, but definitely not worth justifying the $600-$700 prices to upgrade to them. I ended up purchasing some 4AWG wire, and wired it in parallel with the existing alternator, Batt Ground, and Batt B+ wires. More commonly known as the Big 3 upgrade. I also purchased an AGM higher CCA marine battery. My battery charges fine, and no more light dimming issues. I also run my 12K winch off of that same setup with no issues. I'm not a big fan of dual battery setups. Takes up too much space, too much costs and complications in battery replacement. I prefer to get a better marine battery, and upgrading the wiring so that it is capable of charging and delivering the additional power draw requirements.
Thread Starter
JK Enthusiast
Joined: May 2014
Posts: 265
Likes: 2
From: SoCal
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.
off to do some wiring am I
JK Jedi Master
Joined: Mar 2007
Posts: 14,800
Likes: 374
From: Midwest City, OK
... I'm not a big fan of dual battery setups. Takes up too much space, too much costs and complications in battery replacement. I prefer to get a better marine battery, and upgrading the wiring so that it is capable of charging and delivering the additional power draw requirements.
11:15 if not forwarded automatically (and then continues on part 9) ...
https://youtu.be/0Eyq1klfCkI?list=PLNmyT4ZqfdQmBSNAXSfR8OG9jIeB94XTz&t=675
JK Jedi
Joined: Apr 2010
Posts: 4,468
Likes: 221
From: SE Michigan
Different strokes for different folks. I do want to clarify, however, that I run AGM batteries. They still fail. Ray had one fail on the Dalton Highway during our Al-Can trip. Fortunately, he also has dual-batteries, so we weren't looking at 750 miles of overland travel with me having to jump him every time we stopped.
11:15 if not forwarded automatically (and then continues on part 9) ...
https://youtu.be/0Eyq1klfCkI?list=PLNmyT4ZqfdQmBSNAXSfR8OG9jIeB94XTz&t=675
11:15 if not forwarded automatically (and then continues on part 9) ...
https://youtu.be/0Eyq1klfCkI?list=PLNmyT4ZqfdQmBSNAXSfR8OG9jIeB94XTz&t=675
What's the use cases for a dual battery setup? Higher current output? Then I would rather get a larger battery. Having a backup battery available in case the primary drains? Then I would rather have a backup battery without taking up the additional space under the hood with all the additional wiring.
JK Jedi
Joined: Dec 2010
Posts: 5,642
Likes: 486
From: Knoxville
Dual battery is a good backup plan without taking up the extra cargo space. I was coming home one night and I had a battery die on me at midnight 2 hours north of my home. Not an issue with the dual battery- just hit the solenoid and the jeep runs as advertised.
I've also got mine set up with my auxiliary lighting (all LED), winch, and on board air (again with the cargo space concerns in a 2dr). I can run the compressor or even the winch and still have enough juice to start the jeep.....even though I'm typically idling while running either accessory.
I've also got mine set up with my auxiliary lighting (all LED), winch, and on board air (again with the cargo space concerns in a 2dr). I can run the compressor or even the winch and still have enough juice to start the jeep.....even though I'm typically idling while running either accessory.
JK Newbie
Joined: Jan 2015
Posts: 61
Likes: 0
From: Litchfield Park, AZ
Originally Posted by Mark Doiron
I had checked into this as part of installing a dual-battery system. Ended up not doing it and it has not been a problem for me. But, this is the company whose alternator I was considering ...
Premier Power Welder, LLC
FYI, if you do upgrade, than I'd recommend upgrading the alternator wiring harness as well. You're probably on your own to build that.
EDIT: Just another thought ... Have you considered installing a second battery and wiring the trailer to that? With a proper battery isolator, you won't have any problems keeping both batteries charged. Overland Journal's latest issue has a review on some of the different isolator options, along with explanations of the technology used and advantages/disadvantages of each.
If you're unfamiliar with the isolators, they insure that the start battery is charged before the isolator connects the batteries together to charge the aux/house battery. I monitor both of my battery voltages and it does a nice job. Typically takes a couple, three minutes for the isolator to be happy that the start battery is charged enough to tie the aux battery in. That is because in my system the bulk of the voltage demand when parked is loaded onto the aux battery only (the one exception being the fridge).
Premier Power Welder, LLC
FYI, if you do upgrade, than I'd recommend upgrading the alternator wiring harness as well. You're probably on your own to build that.
EDIT: Just another thought ... Have you considered installing a second battery and wiring the trailer to that? With a proper battery isolator, you won't have any problems keeping both batteries charged. Overland Journal's latest issue has a review on some of the different isolator options, along with explanations of the technology used and advantages/disadvantages of each.
If you're unfamiliar with the isolators, they insure that the start battery is charged before the isolator connects the batteries together to charge the aux/house battery. I monitor both of my battery voltages and it does a nice job. Typically takes a couple, three minutes for the isolator to be happy that the start battery is charged enough to tie the aux battery in. That is because in my system the bulk of the voltage demand when parked is loaded onto the aux battery only (the one exception being the fridge).