Strange charging problem

[professor-patrick]

This is a weird one.  My voltage regulator only charges when it is not grounded.  If i bolt it to the firewall it stops charging battery.  As long as it is hanging free, all works good.  Actually too good, getting 16 or more volts to battery.  Any ideas?  Its a 69 charger, 2 field alternator, one side grounded. 

[Pete in NH]

Hi,

Some thing strange indeed is going on. What type of regulator are you using? The original regulator used an electromechanical relay/resistor set up. Many of the replacement types for this unit are now electronic replacements. When you unground the regulator the fact that the alternator output goes to 16 volts tells me that you are likely appling something close to full battery voltage to the field winding of the alternator. When you ground the regulator and the output of the system goes lower than battery voltage may indicate  a bad regulator. If I were running a two field wire alternator I think I would would just switch over to the Chrysler two wire system and a Mopar electronic regulator.

[professor-patrick]

Figured it out - had to adjust the regulator spring - it was stuck on ground, so when removed from ground to the body it would charge.

[nrt69]

im having a similiar problem. replaced basically all the ignition and electronic components under the hood including a mechanical adjustable volt regulator. The car was charging, probably too much so cause my ammeter gauge was usually reading very high. Then all of a sudden it stopped and the ammeter doesnt read anything at all. I found out the battery wasnt being charged cause i have to put my batt on a battery tender every 3 weeks or so. Battery votls is 12.8, alternator output is 13.8. If i disconnect the neg batt cable and hook up a test light, the light comes on. someone said its drawing power from somewhere.

how does the charge from the alternator get from it to the battery? what should i troubleshoot first?

also, ive requested that I get notified of replies on these posts but ive never recieved one. any suggestions?

[Pete in NH]

Hi,

Battery voltage of 12.8 and alternator/ system voltage of 13.8 indicates as you already know that the battery is not being charged. The wiring path between the alternator and battery is through the dash board ammeter, bulk head connector and a fusible link. All of these points are known trouble spots. What year car are you working on? The fusible link is usually a thing that looks like a piece of blue wire coming off the 1/4 battery stud of the starter relay. It has a connector on the other end that goes to the wiring to the ammeter through the bulk head connector. See if you have battery voltage at that connector. Then check the bulk head connector to see if it has any melted plastic or burnt pins. If everything is okay so far, disconnect the battery and go under the dash and move one wire on the ammeter to connect directly to the other ammeter wire. If things start to work again the ammeter is burnt out which is not uncommon. Good luck and let us know what you find.

[nrt69]

If everything is okay so far, disconnect the battery and go under the dash and move one wire on the ammeter to connect directly to the other ammeter wire. If things start to work again

what do you mean if things start to work again? meaning the battery is being charged again?

[lukedukem]

If everything is okay so far, disconnect the battery and go under the dash and move one wire on the ammeter to connect directly to the other ammeter wire. If things start to work again

what do you mean if things start to work again? meaning the battery is being charged again?

yes. pete is saying to do this to eliminate the ammeter. if you do this and hook battery back up and everything is normal then that indicates the ammeter was the bad spot.