High Voltage at battery
05-25-2014, 05:04 PM
#11
Senior Member
LMAO - LOVE the meter w0lvez - but i swear I tested the battery before install and after and got 14.6 volts......but...
got really curious about the voltage thing so dug out my better meter in the garage and behold 12.62 volts.
BTW ALL - I now got a handheld digital meter will sell for cheap.
got really curious about the voltage thing so dug out my better meter in the garage and behold 12.62 volts.
BTW ALL - I now got a handheld digital meter will sell for cheap.
05-26-2014, 10:10 AM
#12
Running Good Again
Thanks everyone for the help, seemed like common sense in beginning to me but never experienced the high Over-volting before on a failed alternator.
I bench tested the regulator and it was shorted - had no resistance at all. Debated between just new regulator or alternator - spent the extra $100 and went alternator with lifetime warranty since the old one had a squeak when spun. Replaced some worn vacuum tubes while had it torn apart too.
Running great again, appreciate the help. Also found out that my handheld voltmeter was faulty (and/or cheap). Once got truck back to my garage pulled out my better voltmeter and battery reading was 14.2 under charge load and 12.6 in rest. The other meter (the one in the trash now) was still reading battery at 14.6
I bench tested the regulator and it was shorted - had no resistance at all. Debated between just new regulator or alternator - spent the extra $100 and went alternator with lifetime warranty since the old one had a squeak when spun. Replaced some worn vacuum tubes while had it torn apart too.
Running great again, appreciate the help. Also found out that my handheld voltmeter was faulty (and/or cheap). Once got truck back to my garage pulled out my better voltmeter and battery reading was 14.2 under charge load and 12.6 in rest. The other meter (the one in the trash now) was still reading battery at 14.6
05-26-2014, 12:09 PM
#13
Senior Member
Your Mutimeter is like Ford's Instrument Voltage Meter.. I wonder if that is really working.
Look for Voltage Drop in your Wiring.. Clean & remove all corrosion on the terminals especially the Starter Ground Cable which could be the reason in the first place why the alternator is working hard.
Make Sure You don't skip this..
Connect the Voltmeter Test Lead to the Voltage Regulator Ground and
Positive Battery Post (Not Terminal) the Voltage Drop should be less than 0.05V
Look for Voltage Drop in your Wiring.. Clean & remove all corrosion on the terminals especially the Starter Ground Cable which could be the reason in the first place why the alternator is working hard.
Make Sure You don't skip this..
Connect the Voltmeter Test Lead to the Voltage Regulator Ground and
Positive Battery Post (Not Terminal) the Voltage Drop should be less than 0.05V
Last edited by w0lvez; 05-26-2014 at 02:00 PM.
07-07-2019, 06:23 AM
#15
Senior Member
Since you had a working alternator I doubt this is for is for you so this is just general info because of some of what I've read here. What is the voltage at the L terminal on your alternator? It should be somewhere between 4.5 and 5 volts or battery voltage. Ford used 2 different types of alternators and you have to have the right one for your vehicle. If you have a new alternator and you have one operating at battery voltage rather than the 4.5 to 5 volt that could be your problem. If you should have the smaller voltage alternator and have the right alternator but you are reading battery voltage your alternator is bad. Off hand, I don't know what your alternator spec is. In 2004 or 2005 depending on the vehicle and all later years, the PCM automatically controlled the voltage with a 128 Hz pulse width signal. Some newer alternators work fine on older vehicles but most don't. Can't tell you why that is.
Regardless of the above your PCM can be the cause of your problem also. Particularly if you have a short to power but to ground can also be the culprit. The problem you are experiencing is more commonly the alternator as suggested already. Your best bet to fix this is to take your truck to an automotive electrical shop. They can probably tell you what's wrong in minutes instead of you chasing a problem and spending money on every "maybe."
Regardless of the above your PCM can be the cause of your problem also. Particularly if you have a short to power but to ground can also be the culprit. The problem you are experiencing is more commonly the alternator as suggested already. Your best bet to fix this is to take your truck to an automotive electrical shop. They can probably tell you what's wrong in minutes instead of you chasing a problem and spending money on every "maybe."
