Battery boiling over

[class87]

From: LJ-TJ  (Original Message)
Sent: 9/29/2008 11:51 PM

Well just installed a new volt regulator to no availe. Volt meter still climbs a pegs a 16 volts. Any ideas.



From: The_Handier_Man
Sent: 9/30/2008 12:05 AM

Have you really checked the voltage with a meter?  And is the battery really boiling?  Maybe an auto parts place can hook up some machine to test at least part of the system and tell you what is not the problem,  Les



From: ontheroadagain7
Sent: 9/30/2008 10:17 AM

make sure you have a good ground to the regulator you can add a wire to the mounting bolt then to battery neg. terminal or to the engine block 



From: denisondc
Sent: 10/1/2008 6:38 PM

Some of this will be a repeat of things slantsixness said:

Here is what I would do:
First check whether the voltmeter is reading more or less correctly with the ignition on, but the engine not running. It should show about 12 volts, but might say 11, if you have other accessories running. This is just to make sure the voltmeter isnt 'nuts'. I am assuming you are talking about the voltmeter that is mounted in the dashboard, not a portable VOM that has electronics in it, like a Digital or Analog VOM often has.
Then check the battery voltage with the engine off. This check needs to be done at the battery posts; not on the terminals, not elsewhere on the RV. So requires a portable VOM, either digital or analog. It should say about 12.6, if the RV has been sitting for an hour or two with the engine stopped.
Then start the engine, and without delay, check the voltage at the battery again. It should go -up- from 12.6 volts. That just establishes that the alternator is really connected to the battery, that there isnt a fault in the wiring from the alternator output back to the battery.
Then measure the output voltage at the alternator. This is the large terminal on the alternator, and should be measured twice; once from the output terminal to the case of the alternator, and also from the output terminal to the frame of the RV. If the voltmeter on the dashboard is pegging at 16, then this alternator output terminal would be reading something higher than 16. Be careful, an alternator is capable of putting out more than 40 volts, some of them can put out over 100 volts - if the output terminal isnt connected to a load & the engine is revved up.
If the alternator is putting out an overvoltage (anything over 15 or 16 I think, though this would depend on the integrity of the wiring connecting it to the battery) and the battery is showing more than 14.5 or so volts at its posts, or more than 14.0 if the engine has only been running for a few minutes, then....

The alternator charges because the 'field' coil in its rotor has voltage across it, which creates the spinning magnetic field. There are two small wires running to the alternator for this. On my Winnie one wire is 18awg red, and should have 11 or 12 volts on it anytime the ignition is on. The other wire is 18awg light green, and runs to the voltage regulator. This wire is 'grounded' by the voltage regulator to make the alternator charge. So if you pull this wire off the alternator, (or unplug the pyramid shaped connector on the VR) the alternator should cease to charge. If you pull this wire off and the voltmeter on the dashboard still reads 16 volts, let us know...so I can try to think of what could possibly cause such a situation.
The voltage regulator learns what the battery voltage is via a 'sense' wire. It is red, and runs from the "centered' wire on the pyramidal VR connector, back to a splice that is close to the ignition resistor. If that splice point is lower than battery voltage (about 12 volts with the engine running, and maybe 11 volts with the ignition on but the motor stopped) because there is a corroded wire or bad connection between that splice and the battery's 12 volts, then the VR will be 'sensing' a voltage that is too low, and it will tell the alternator to CHARGE More! Thus a bad wire (corroded or broken strands) in the wire suppling the ignition resistor, can also affect how much the alternator charges. This circuit runs from the battery, through the fusible link, through a connector somewhere in the wiring harness, through the ammeter, through the ignition switch and its 8 pin connector, and finally to the splice near the ignition switch. Its probably 20 or 25 feet of wire, some of which runs right past the engine above the hot exhaust manifold. And the ground connections are just as important as the ones from the positive terminal of the battery.

...........If you can measure from the case of the VR back to the negative post of the battery, you should not seem more than 1/2 volts between the two points - with the engine running and the alternator doing its 'overcharging'. If you do you should add a ground wire to bring the case of the VR to the same 'potential' as the negative post of the battery.

If you pull the connector off of the VR, the alternator output should drop to zero, and the ammeter needed should center, and the battery voltage should begin to drop back to 12 volts. The drop should happen in about 5-10 minutes, due to the several amps being drawn by the ignition system.
If it does, look for a bad ground to the VR, or a bad voltage on the 'sense' wire.
If it continues to overcharge, then I think you must have a wire from the VR to the alternator field coil connections that is shorted to ground. It would be the light green wire that had this problem, not the red wire.



From: The_Handier_Man
Sent: 10/1/2008 7:54 PM

Wasn't this the rig that was welded on?  Seems like I was told to disconnect the Battery when welding or it could blow out something?  Just wondereing,   Les



From: normstow
Sent: 10/9/2008 1:58 PM

I had the same problem with my 76 Apollo - Dodge M500 chassis, although mine would overcharge intermittently.  After checking all wiring, particularly grounding, and replacing the voltage regulator, (more than once), out of desperation, I replaced the alternator.  Bingo! problem solved.  I don't understand why the alternator can cause this, but I did read on another forum, that this can happen.  I can only confirm that it totally fixed a problem that caused a lot of frustration.  I have done 5 trips since the alternator was replaced, with no recurrence of this problem.  I have installed an atermarket voltmeter, which gives a good reading on the state of the charging system.  Without the voltmeter, this problem would go unnoticed, as the stock ammeter would still show a positive charge.  Good luck, hope this helps.

Norm 



From: denisondc
Sent: 9/25/2008 3:47 PM

A fully charged battery should read about 12.6 volts if there is no load on it and it hasnt been charged or heavily discharged in the last 30 minutes. With the engine running, the battery should probably be at least 13.2 volts, rising to 14.6 or so after a couple of hours of the RV being driven in daylight. If you have a voltmeter on the dashboard, it probably isnt connected directly to the battery - so is reading voltages across somewhere else in the system. Plus, typical auto type voltmeters probably arent better than 5% accurate, maybe off as much as 10%. With a decent VOM, the voltage measured at the battery posts shouldnt be higher than 14.75 or so .......except in cold weather. The voltage regulator is temperature compensated, and charges to a higher voltage when its cold. This is because a cold battery is less efficient at energy conversion; at turning the charging current into chemical energy in the battery. So the only time you would want to see anything higher than 15.5 volts at the battery terminals might be when the RV was running and the air temp was Zero - and the battery's conversion efficiency was perhaps 10%.
16 volts measured at the battery in mild weather means its either being definitely overcharged (& will boil dry), or is near death from already being low on electrolyte or having an internal crack.
But 16 volts on a dashboard voltmeter would tell me it was probably tinme to add a good ground wire from the metal parts of the dashboard (& the neg. term. on the voltmeter), and run it to the negative cable for the battery.
Since the voltage regulator isnt right at the battery, it can be fooled. Loads on the electrical system that werent part of the original mopar design, may result in low voltage at the dashboard, but not show up as being as low where the VR is located. Especially with 35 year old wiring.

And if its 0°f outside, as much as 90% of the wattage that is being sent to charge the battery will go to warming it up.



From: From: LJ-TJ

Thanks for taking the time to help. The part that sticks in my mind had something to do if the voltage regulator wasn't working right it would allow the volt meter to creep up past 14 volts to peg at 16 and eventually over charge the battery and boil it dry or something like that.



From: LJ-TJ
Sent: 10/14/2008 7:59 PM

Up Date:
              I took the new battery out of  Johns bago and put it in mine. No change. Put a new Alternator in, volt meter pegged, put the red probe on the battery,black probe on the ground 15 volts....shoot. Went out checked it at the battery 15 volts....shoot. Bought a new regulator cleaned the grounds etc,etc, etc, no change. Checked at the battery. 15 volts. Waa Hoo eh! 



From: LJ-TJ
Sent: 10/16/2008 10:36 PM

Understanding I haven't got a clue what I'm talking about here. I still have an over charging situation of 15 volts. I just went out and started the rig and pulled the one field wire on the alternator off....the voltmeter on the dash dropped to 14 volts and showed 12 volts at the battery. I then replaced it. I then pulled the other field wire off.... the voltmeter on the dash dropped to 14 volts and showed 12 volts at the battery. same,  once I put the wires back on the alternator the volt meter on the dash went back up to 15 volts and when I checked it out at the battery it had gone back up to 15 volts. I really appreciate the suggestion you lads are coming up with, any other thoughts on this situation.



From: GulfCoastFighter0
Sent: 10/18/2008 8:14 AM

I had the same problem with an old Mustang I had. I finally found a voltage regulator that bolted to the rear of the alternator and bypassed the original wiring for the stock regulator. Problem solved!



From: LJ-TJ
Sent: 10/20/2008 9:30 PM

So if you think I'm driving you crazy think how I feel. You've all been there and if you haven't you will be. Soooo what have I found out. Well the guys that re-installed the engine didn't put the ground strap back on to the frame. They bolted it onto the transmission and looped it around and bolted it back onto the transmission.  So I cleaned it up and put it on myself. The end result is that now at idle the volt meter read between 13 and 14 at idle as does the reading off the battery post. How ever when you increase the speed the volt meter on the dash immediately climbs to 15 to 16 volts and the voltage at the battery post reads 15 volts. Also I noticed that the headlights brighten and dim as the speed increases and decreases. Any thoughts, remembering I just put in a new battery..voltage regulator and a new alternator.



From: LJ-TJ
Sent: 10/20/2008 9:37 PM

Denison when you said to measure the output voltage at the alternator. This is the large terminal on the alternator, and should be measured twice; once from the output terminal to the case of the alternator, and also from the output terminal to the frame of the RV. Did you mean to disconect the large black wire from the alternator and then place the red lead on the volt meter to the back of the output terminal on the alternator and the black lead to the alternator read the meter and then put the black lead to the frame some where and then read the meter?



From: denisondc
Sent: 10/21/2008 8:00 AM

Dont disconnect the large wire that is on that large terminal on the alternator, but otherwise do as you stated. If the heavy wire to the alternator is disconnected, all you will learn is how high a voltage your alternator can deliver; which I would estimate at between 20 to 40 volts with the engine idling. If you are using a digital multimeter, be sure to set it to measure DC voltage. If measuring AC voltage, it might read a low voltage, like 1 to 3 volts AC; since it doesnt generate 'pure' DC, but 'pulsating' DC with an AC component. Its not 60 cycle AC either, but a few hundred CPS (or Hertz) at an idle, and much higher when the engine is revved up of course.



From: denisondc
Sent: 10/21/2008 8:15 AM

As for the lights getting brighter when you revv-up from an idle.... That would be normal, since at an idle the alternator is barely putting out enough to compensate for the load of the headlights and clearance lights. The difference in brightness should be minimal though, such as not really noticeable if you arent thinking about it.
At this point it still would seem like you might still have a gremlin in the wiring. Such as: Either the ground wire needs to be thicker and bolted to clean places on the frame and tranny (I prefer to use one of the bolts that holds the starter to the bell housing), or you need to add a ground wire from the frame of the alternator to the front end of the frame of the RV, or the voltage regulator either isnt really well grounded, or its 'sense' signal is coming from a part of the wiring harness that isnt getting full voltage from the ignition switch, or a combination of the above factors. (I say this because I have fiddled with each of these items over the years). Thinking over your problem, I have wondered what would be the result if you ignition resistor was installed wrong, and was loading the supply line from the ignition switch with more current than it was meant to carry. On mine that red wire from ignition switch to the ignition resistor had been melted, gotten corroded inside the insulation, and some of its strands were powderized. I replaced that section of the wire because it looked soo feeble, even though the RV seemed to run okay.



From: LJ-TJ
Sent: 10/21/2008 8:17 PM

1)  First check whether the voltmeter is reading more or less correctly with the ignition on, but the engine not running.Should show about 12 volts, but might say 11 just to make sure the voltmeter isnt 'nuts' (READS BETWEEN 13.5 and 14 volts on the stock dash volt meter.

2)  Then check the battery voltage with the engine off. This check needs to be done at the battery posts; not on the terminals, It should say about 12.6, if the RV has been sitting for an hour or two with the engine stopped. (READS 12 volts on the posts)

3)  Start the engine. Without delay, check the voltage at the battery again. It should go -up- from 12.6 volts. ( It jumps up to 16 volts on the stock dash volt meter and 15 volts at the battery post.)That just establishes that the alternator is really connected to the battery, that there isnt a fault in the wiring from the alternator output back to the battery. Measure the output voltage at the alternator. This is the large terminal on the alternator, and should be measured twice; once from the output terminal to the case of the alternator, and also from the output terminal to the frame of the RV. ( GROUNDED to the alternator it reads 15 volts GROUNDED to the frame it reads 15 volts)If the voltmeter on the dashboard is pegging at 16, then this alternator output terminal would be reading something higher than 16. If the alternator is putting out an overvoltage (anything over 15 or 16 I think, though this would depend on the integrity of the wiring connecting it to the battery) and the battery is showing more than 14.5 or so volts at its posts, or more than 14.0 if the engine has only been running for a few minutes, then....

4)  There are two small wires running to the alternator. One wire is 18awg red, and should have 11 or 12 volts on it anytime the ignition is on.( RODGER THAT not running key on 12 volts.) The other wire is 18awg light green, and runs to the voltage regulator. This wire is 'grounded' by the voltage regulator to make the alternator charge. So if you pull this wire off the alternator the alternator should cease to charge.( RODGER running shows 15 volts 16 on the dash..Removed and the volts on the dash so’s 14.5 and the alternator shows 12 volts) (or unplug the pyramid shaped connector on the VR) If you pull this wire off and the voltmeter on the dashboard still reads 16 volts, let us know...so I can try to think of what could possibly cause such a situation.(Pulled the pyramid off and the dash voltage meter went back to about 14.5)

5)  The voltage regulator learns what the battery voltage is via a 'sense' wire. It is red, and runs from the "centered' wire on the pyramidal VR connector, back to a splice that is close to the ignition resistor. If that splice point is lower than battery voltage (about 12 volts with the engine running, and maybe 11 volts with the ignition on but the motor stopped) because there is a corroded wire or bad connection between that splice and the battery's 12 volts, then the VR will be 'sensing' a voltage that is too low, and it will tell the alternator to CHARGE More! Thus a bad wire (corroded or broken strands) in the wire suppling the ignition resistor, can also affect how much the alternator charges. This circuit runs from the battery, through the fusible link, through a connector somewhere in the wiring harness, through the ammeter, through the ignition switch and its 8 pin connector, and finally to the splice near the ignition switch. Its probably 20 or 25 feet of wire, some of which runs right past the engine above the hot exhaust manifold. And the ground connections are just as important as the ones from the positive terminal of the battery.

6)  If you can measure from the case of the VR back to the negative post of the battery, you should not seem more than 1/2 volts between the two points - with the engine running and the alternator doing its 'overcharging'. If you do you should add a ground wire to bring the case of the VR to the same 'potential' as the negative post of the battery.

7)  If you pull the connector off of the VR, the alternator output should drop to zero, and the ammeter needed should center, and the battery voltage should begin to drop back to 12 volts. The drop should happen in about 5-10 minutes, due to the several amps being drawn by the ignition system.
If it does, look for a bad ground to the VR, or a bad voltage on the 'sense' wire.
If it continues to overcharge, then I think you must have a wire from the VR to the alternator field coil connections that is shorted to ground. It would be the light green wire that had this problem, not the red wire.



From: ontheroadagain7
Sent: 10/22/2008 12:33 PM

check this link it should help you understand what LJ-TJ is saying check the wiring schematic at the bottom of the page ignore the wire colors shown if yours has different color wires they will still be wired the same way regardless of the color
http://www.allpar.com/history/mopar/electrical.html



From: LJ-TJ
Sent: 10/22/2008 4:16 PM

Well Beats Me......It looks like I'm going to have to live with 15 volts....hope I don't screw up a new battery. Thanks for all your help guys. If anything pops up in the future you'll be the first to know......