Rewiring charging system?? - JeepForum.com
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post #1 of 37 Old 12-17-2013, 05:27 PM Thread Starter
flcracker
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Rewiring charging system??

I just put a new battery in my 92 (2.5 stock alt) and I had the alt checked before I did the battery and it checked good. The problem is still the same, voltmeter reads low when running.

Just got back from Advance Auto (good guys) and according to their little black box, the alt isn't getting the charge to the battery and I am wondering if the alt is still good, could I rewire the charging system straight from the alt to the battery or does that bypass the regulator function of the PCM?

In time I will be going to a bigger (136 amp) alternator so this is something that would have to be done anyway??


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post #2 of 37 Old 12-17-2013, 06:03 PM
superj
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I think you have to stay wired in your current set up. What does a digital multimeter read at your battery when the jeep is running?

I don't feel like working on anything at this time so i sold my yj.
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post #3 of 37 Old 12-17-2013, 06:07 PM Thread Starter
flcracker
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Finally broke down and got a multimeter and found the directions "lacking" but I did find a youtube video to check for resistance from the alt to the battery. Gonna give that a whirl tomorrow and see whats up. I was just wondering if it was the wiring, if I could upgrade to bigger cables so when the little 72 amp alt does bite the dust, I would be able to pretty much just bolt in the bigger one??

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post #4 of 37 Old 12-17-2013, 07:53 PM
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You can't just bolt on the bigger one exactly.

http://www.jeepforum.com/forum/f12/1...07/?highlight=

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post #5 of 37 Old 12-17-2013, 08:00 PM
TSEJEEPERS
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Quote:
Originally Posted by flcracker View Post
I just put a new battery in my 92 (2.5 stock alt) and I had the alt checked before I did the battery and it checked good. The problem is still the same, voltmeter reads low when running.

Just got back from Advance Auto (good guys) and according to their little black box, the alt isn't getting the charge to the battery and I am wondering if the alt is still good, could I rewire the charging system straight from the alt to the battery or does that bypass the regulator function of the PCM?

In time I will be going to a bigger (136 amp) alternator so this is something that would have to be done anyway??
Yes you can do this.
There are alot of good write ups on how to do it. Here is one of them.
http://www.jeepforum.com/forum/f12/a...ccess-1424780/
Most go to a bigger alternator but I see now reason why you could not do it with the stock one.

93 YJ SOA 2" springs front, XJ springs rear w/main leaf added, High pinon 9 inch rear detroit locker front Dana 44 ARB 4.56 Gears, 36 inch Irok tires too much to list.
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post #6 of 37 Old 12-17-2013, 09:02 PM
Raindem
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Before dumping money into bigger alternators and cables, check the basics. 1) Check & clean all grounds, especially battery to block 2) Check alternator wiring for breaks and good connections 3) Measure your voltage drop 4) Check for ground voltage, which would indicate a short somewhere 5) Read the running battery voltage with your new multimeter and compare to the gauge 6) Read the running battery voltage with different accessories turned on and off.

If it ain't broke... break it.
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post #7 of 37 Old 12-17-2013, 09:44 PM
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You can run a cable straight from the battery positive terminal and the alternator batt+ terminal. However, you will be bypassing the fuse setup, so you need to add a fuse in the cable. An ANL fuse close to the battery will work well. http://www.donrowe.com/category-s/1845.htm

Search for "Big 3 upgrade". It is what the obnoxious stereo people do and one part of it is the fused cable from the battery to the alternator.

Not sure because mine is earlier set up differently, but I think there are two fuses in the fusebox under your hood for the battery/alternator connection. One could be blown and causing your problem.
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post #8 of 37 Old 12-18-2013, 07:17 AM Thread Starter
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Was looking at the link Anti provided (I got to see pics to really get it) and I like the parts list for it.... Have a question though; would it be better to use Marine cables and terminals? Is tinned copper better/worse/no different than regular copper cable??

I am on the Gulf Coast in SW FL and you can't swing a dead cat without hitting a marine supply shop.

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post #9 of 37 Old 12-18-2013, 07:19 AM
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Quote:
Originally Posted by flcracker View Post
Was looking at the link Anti provided (I got to see pics to really get it) and I like the parts list for it.... Have a question though; would it be better to use Marine cables and terminals? Is tinned copper better/worse/no different than regular copper cable??

I am on the Gulf Coast in SW FL and you can't swing a dead cat without hitting a marine supply shop.
Couldn't hurt. Just make sure you've got the right solder for it.

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post #10 of 37 Old 12-18-2013, 10:04 AM
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Did you diagnose the real problem yet?

I also may be wrong on this but doesn't the ECM regulate the voltage?

Lou

I have a jeep...and it is modified...I win.

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post #11 of 37 Old 12-18-2013, 10:13 AM
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if you upgrade the wire from the alt to the battery also add a wire from the alt mount to the battery-. think of the power sysetm as a big loop if you just do the + side you are only doing half the loop and dont gain anything.
i just did mine and did

alt+ to batt+
batt+ to pdc+
bat+ to custom buss bar
batt- to alt case
bat- to body

yes the ecm does control the alt.
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post #12 of 37 Old 12-18-2013, 10:13 AM
dancytron
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Its not a space shuttle. Welding cable and regular copper lugs are fine.

Marine terminals will make it easier to set up.
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post #13 of 37 Old 12-18-2013, 10:15 AM
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Quote:
Originally Posted by kingcat400 View Post
if you upgrade the wire from the alt to the battery also add a wire from the alt mount to the battery-. think of the power sysetm as a big loop if you just do the + side you are only doing half the loop and dont gain anything.
i just did mine and did

alt+ to batt+
batt+ to pdc+
bat+ to custom buss bar
batt- to alt case
bat- to body

yes the ecm does control the alt.
Forgot the ground to the block, sir.

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post #14 of 37 Old 12-18-2013, 10:18 AM
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Quote:
Originally Posted by flcracker View Post
I just put a new battery in my 92 (2.5 stock alt) and I had the alt checked before I did the battery and it checked good. The problem is still the same, voltmeter reads low when running.

Just got back from Advance Auto (good guys) and according to their little black box, the alt isn't getting the charge to the battery and I am wondering if the alt is still good, could I rewire the charging system straight from the alt to the battery or does that bypass the regulator function of the PCM?

In time I will be going to a bigger (136 amp) alternator so this is something that would have to be done anyway??
When was the last time those battery cables got changed? If the Alternator is doing it's job but the voltage won't travel to the battery to charge it up then the wiring is the problem....IF the ECM isn't.

Remove both 6 AWG battery cables. I think the cables are twisted up clockwise.
Twist each one of them counter clockwise as much as is possible without breaking off the battery lug. Then check for a good clean shiny chassis ground on your - battery cable.

Slap them back on your battery and fire the YJ up. What does the gauge say now?

If the reading went up internal corrosion of the battery cables is quite possible.

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post #15 of 37 Old 12-18-2013, 10:27 AM
kingcat400
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Quote:
Originally Posted by Anticanman View Post
Forgot the ground to the block, sir.
i ran a jumper from the alt case to the block.
its all 1/0 hyperflex
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