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Unread 05-25-2013, 01:07 PM   #1
xcaliber81
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1994 ZJ 
 
Join Date: Jul 2012
Location: Prince George, B.C
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is my charging normal?

So this morning it was cool and on the way to work I noticed my battery guage was at 14 normal I think? But as it gets hot outside it drops to the line below 14, between the 1/2 and 1/4 mark.

Also this might be related but I notice at times when my sub is pounding at times the bass wont be as loud its as if someone turned the sub down a bit and then after about a min it will go to what it was again. Almost as if its not getting enough power for a bit. I am using 4 guage power and ground wire fused.

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Unread 05-25-2013, 02:01 PM   #2
Oldfrog
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Sounds like the alternator isnt up to the amt of current your stereo is pulling. Run it for a day without the stereo on and see what happens.
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Unread 05-25-2013, 02:02 PM   #3
Candymancan
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Get a mulimeter and check put the probes on the pos and neg of the battery with the amp running and without it running and see what the voltage is reading
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Unread 05-25-2013, 02:25 PM   #4
xcaliber81
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Ok ill try after work thanks
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Unread 06-22-2013, 06:26 PM   #5
xcaliber81
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ok so i tested it out and it said it was charging normal however im noticing while its hot at full load, no lights but ac full blast stereo pumping and driving lights on all at idle while im driving it goes up to i assume 13.
20130622_165827.jpg  
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Unread 06-22-2013, 06:27 PM   #6
xcaliber81
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your looking at my charging not my gas lol.
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Unread 06-23-2013, 02:01 AM   #7
Candymancan
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That's too low, your alternator isn't up to the task of charging with that stereo system you got in there.. You have a 90 amp alternator.. that's what the 4.0's came with for your year.. I replaced my moms 116A alternator that died with a 90amp because I was lazy to order online and needed an alternator now.. and no store locally sold a 116.. they only sell 90 for the 4.0's.. it charges just fine under normal circumstances but if I hit all 4 windows, with my a/c lights, and stock stereo on the charge will drop to where yours is.. 90a isn't enough for your sub trust me.. 90A is the bare min to power a Jeep with what it has stock

Just get a bigger alternator, the position your needle is on right is the 12v mark.. These Jeeps charge at 13.8v, like I said get your multimeter out or go buy a cheap one.. hell harborfreight gives them away... Put it on the 20 Setting on the left and put it your batter with all your stuff running.. garuntee you'll see something like 12.5v. Replace your amp with the 116a ones for the 4.0 or spend the money on something bigger like a 136A.. Altho I dunno if the 136's will mount on a 4.0's bracket.

According to ratmonkey, the engine uses I think he said 40A to just run, the headlights use 10A fog lights 10A, A/C 12Amps that's 72A, then I think he said the stereo uses like 10-20A that's 80A, then you got power windows, and heated seats and power seats ect.. That's why my 4.0 with the 90 when I use all 4 windows the power drops to what yours is at because I don't have enough power to run EVERYTHING simultaniusly even if rolling all 4 windows down at the same time is a stupid way to test that.. My 5.9 tho has power seats and heated seats, and fog lights my 4.0 doesn't if I do the same test with the windows, lights a/c and stereo which btw on my 5.9 pulls mow power then the 4.0 does.. My power stays fine.. even with my electric fan motor.. that's because I have a 150A alternator

How how amps do you think that sub is pulling ? How many watts is it ? What OHMS is it running off 4 or 2 ? A 1200W amplifier will use somewhere around 100AMPS.. A 180w Stereo system like in my 5.9 uses only like 15ish.. If you have a 600w system that's around 50Amp... So think about this... 50 Amps, plus the engines 40-50.. and your 90A alternator... means you cant power anything else.. So yea I know im running my mouth now but your alternator isn't up to the task..

Since you don't have enough AMPS to run your system.. your

A. Killing your alternator and your car battery by running that sound system
B. Your sound system isn't being powered properly hense why It sounds like crap with no bass.. Get a bigger much bigger alternator and you'll be fine. I would recommend something 150 or more
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Unread 06-23-2013, 02:09 AM   #8
xcaliber81
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id like something bigger than 116a
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Unread 06-23-2013, 02:20 AM   #9
Candymancan
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Yea I edit my post a lot.. I recommended a 150A or bigger, I just don't know where you can get one.. I know local stores wont sell them so you gatta look online.

How many watts is your amplifier/sub ?
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Unread 06-23-2013, 01:03 PM   #10
xcaliber81
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Its not super huge its a 12" jl audio and a cheapo 600 watt dual amp. I got the amp free and its only going to be used untill I can buy a better one. Also im using 4ga wiring.
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Unread 06-23-2013, 01:13 PM   #11
junkyjeep
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If the volts are reading correct at the battery then it's just a faulty stock gauge mine has been that way for a long time . I keep saying someday I'm gonna trace the gauge wire out and clean it or replace most likely it's a corroded wire to the gauge itself
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Unread 06-23-2013, 01:20 PM   #12
xcaliber81
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but when it get low like that i can feel the engine vibrate more like its working more.
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Unread 06-23-2013, 01:23 PM   #13
xcaliber81
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i read something about changing the wire size that goes to the alt to the pdc and then to the battery is that true.
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Unread 06-23-2013, 10:44 PM   #14
Candymancan
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Quote:
Originally Posted by xcaliber81 View Post
Its not super huge its a 12" jl audio and a cheapo 600 watt dual amp. I got the amp free and its only going to be used untill I can buy a better one. Also im using 4ga wiring.

600 watts uses like 40-50Amps of power... Your engine is using 40-50 amps, your alternator can only put out max 90Amps.. Do the math man.. That's why your engine is sputtering or shaking more when the amp is on you don't have enough power to run the engine properly the ignition coil/spark plugs ect are what is causing the engine to vibrate more when your amp is on due to lack of power.. A 136A+ min alternator should be enough to run all that if you have a 600w AMP in there. With that amp, headlights and A/C and with the engine running your using around 120AMPS not counting window motors when you roll them down or up and if you have power seats. So honestly like I said start looking for a better alternator, and disconnect your amp or don't use it if this is your daily driver.. you don't want to blow your alternator by forcing it to run like that. Not to mention all that strain on the system altogether could cause haywire to your pcm and battery.. remember the voltage regulator is in the pcm..
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Unread 06-24-2013, 12:17 AM   #15
HandsOn
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Do the '94's also have the "Battery Temp Sensor in the tray?
If so, that could explain a little of what you see. Not sure if your amp is causing anything other than what has been described (overtaxing the low powered stock alt), but if a temp sensor or PCM gets a little sensitive, it could be reducing the output of the alternator because that's what it does. Compounding your high amp draw issue.
Even worse if the PCM is having trouble interpreting what the sensor is telling it, or if the sensor itself is going wonky.
Add to all that an older alternator that may no longer be capable of putting out it's rated current, and you've got a recipe for low performance of your electrical system.

Some good info posted here about how to test each aspect, but you get the picture. An already low output being reduced even more by circumstances. Plenty of fixes.
Starting with the higher powered unit already recommended.

Paul
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