Lights and the Power to run them
Thread Starter
JK Enthusiast
Joined: Sep 2008
Posts: 136
Likes: 0
From: That little town south of Grand Canyon, Arizona
Lights and the Power to run them
I am thinking of SERIOUS Lighting in front. Basically a 2 way low/hi beam "for off road use only". There are WAY to bright and consume WAY too much energy to hook up to the battery.
Has anyone here replaced their alternator so it can withstand this power drawl?
Has anyone found a way to dual strap in 2 Red Top Batteries?
Has anyone here replaced their alternator so it can withstand this power drawl?
Has anyone found a way to dual strap in 2 Red Top Batteries?
JK Super Freak
Joined: Apr 2007
Posts: 1,699
Likes: 2
From: Lancaster Pa
WOW, what kind of lighting are you using??
The factory JK alternator is rated at 160 amps at 14.5VDC. That is already a high output alternator as compared to the older Wrangler and Cherokee alternators. Are you sure your battery and alternator are working correctly.
The monitoring system on the JK is not that good, and even though it may tell you the system is okay, all may not be well. For example if one of the 3 windings would fail, the alternator would still provide power however only at 2/3 it's capacity, and the detection system might not pick this up. Not to say that is the case, however you can check the output with a voltmeter or multimeter. If you have not done so that would be a good simple check to make.
The battery alone should read around 12VDC statically. After the battery is checked in the static condition, check with the engine running. The battery should now read between 14-14.5 VDC. That would indicate that the alternator is outputting the correct voltage. If the alternator is working correctly, then at the nominal RPM, it should be producing up to 160 amps, dependent upon how much of a load the system is drawing.
At 14.5 VDC with 160 amps available, the system should be able to power up to 2304watts. Some of that wattage would be used to supply power to keep the engine running, for recharging the battery, and of course any aux equipment you have running such as the A/C, stereo, and so forth.
The engine should not take that much to keep running once started, and a good battery should not require that much either. The A/C might be somewhat of a drain as well as a large power amplifier for a stereo, however even with those things running there should still be a reasonable amount left over for lighting. Keep in mind the lower RPM you are traveling at the less power output from the alternator. I would think the nominal output of a stock JK alternator would be somewhere in the 2400-3000 RPM range.
I've seen alternators for Jeeps that have outputs of up to 220 amps, however they are very expensive and hard to come by, and most likely not available for the JK just yet. Another possibility would be to check with your local alternator shop. They may be able to rewind your factory alternator to provide more output. This may however cost you an arm or a leg, and normally rewound alternators that provide higher output will only do so at higher RPM's. At a lower RPM of say 1100 the output would be substantially lower than what it was at stock.
Another alternative would be a dual battery setup using two deep cycle batteries, with an isolator. This is somewhat common practice, and more information can be found by talking to your local 4X shop. I would assume that is what you are referring to when you say "strapping two red Top batteries"
Hooking up two batteries in parallel would of course provide you with the output in Ah of both batteries yet the VDC would remain constant at 12.
This could put you in very dangerous waters, and I would not even recommend that route.
Good luck.
The factory JK alternator is rated at 160 amps at 14.5VDC. That is already a high output alternator as compared to the older Wrangler and Cherokee alternators. Are you sure your battery and alternator are working correctly.
The monitoring system on the JK is not that good, and even though it may tell you the system is okay, all may not be well. For example if one of the 3 windings would fail, the alternator would still provide power however only at 2/3 it's capacity, and the detection system might not pick this up. Not to say that is the case, however you can check the output with a voltmeter or multimeter. If you have not done so that would be a good simple check to make.
The battery alone should read around 12VDC statically. After the battery is checked in the static condition, check with the engine running. The battery should now read between 14-14.5 VDC. That would indicate that the alternator is outputting the correct voltage. If the alternator is working correctly, then at the nominal RPM, it should be producing up to 160 amps, dependent upon how much of a load the system is drawing.
At 14.5 VDC with 160 amps available, the system should be able to power up to 2304watts. Some of that wattage would be used to supply power to keep the engine running, for recharging the battery, and of course any aux equipment you have running such as the A/C, stereo, and so forth.
The engine should not take that much to keep running once started, and a good battery should not require that much either. The A/C might be somewhat of a drain as well as a large power amplifier for a stereo, however even with those things running there should still be a reasonable amount left over for lighting. Keep in mind the lower RPM you are traveling at the less power output from the alternator. I would think the nominal output of a stock JK alternator would be somewhere in the 2400-3000 RPM range.
I've seen alternators for Jeeps that have outputs of up to 220 amps, however they are very expensive and hard to come by, and most likely not available for the JK just yet. Another possibility would be to check with your local alternator shop. They may be able to rewind your factory alternator to provide more output. This may however cost you an arm or a leg, and normally rewound alternators that provide higher output will only do so at higher RPM's. At a lower RPM of say 1100 the output would be substantially lower than what it was at stock.
Another alternative would be a dual battery setup using two deep cycle batteries, with an isolator. This is somewhat common practice, and more information can be found by talking to your local 4X shop. I would assume that is what you are referring to when you say "strapping two red Top batteries"
Hooking up two batteries in parallel would of course provide you with the output in Ah of both batteries yet the VDC would remain constant at 12.
This could put you in very dangerous waters, and I would not even recommend that route.
Good luck.
Last edited by Lorrel; Oct 26, 2008 at 02:55 AM.
JK Junkie
Joined: May 2007
Posts: 2,262
Likes: 1
From: Des Moines, Iowa
You should be able to run any automotive light on the market without worring about your electrical on your Jeep. Just run it with a relay to the battery. I would think that with people running 5 sets of 100 watt lights you should be fine since I have never seen anything more powerful than a headlight around 150 watts.
JK Super Freak
Joined: Nov 2007
Posts: 1,595
Likes: 0
From: Rhode Island
I can run all of the front lights at idle and still maintain 13V charging. Bounced right back with minor throttle. After changing my alt pulley I'm at 13.9V at idle.
Which lights are you planning on running???
Which lights are you planning on running???
Thread Starter
JK Enthusiast
Joined: Sep 2008
Posts: 136
Likes: 0
From: That little town south of Grand Canyon, Arizona
Good info for sure !!! Thanks.
2 Batteries will probably be the way I go, with isolator.
The lights I was looking at are 180 watts each. (12 volt, also come in 24 volt)
Put two and two together and you know they are landing lights for a plane. They can only be on while airflow is going over lights to cool them. So these aren't something that I would use at idle to put up a tent....
2 Batteries will probably be the way I go, with isolator.
The lights I was looking at are 180 watts each. (12 volt, also come in 24 volt)
Put two and two together and you know they are landing lights for a plane. They can only be on while airflow is going over lights to cool them. So these aren't something that I would use at idle to put up a tent....
