Not charging at 12 volts

-
twayne24365

twayne24365

Well-Known Member
Joined
Jun 18, 2013
Messages
1,552
Reaction score
332
Location
Maryland
ok fellas, here's the run down...
Fairly new battery in the trunk
One wire 63amp alternator
Msd6al ignition
And really the only electrical accessory is a fuel pump.
I had to replace the alternator due to a bad bearing, used to show 14volts with key on, then 12 volts while running. The replacement alternator shows a constant 10.5 volts with key on and while running, any ideas? I'm no electrical guru haha
Thanks!
 
twayne24365 said:
ok fellas, here's the run down...
Fairly new battery in the trunk
One wire 63amp alternator
Msd6al ignition
And really the only electrical accessory is a fuel pump.
I had to replace the alternator due to a bad bearing, used to show 14volts with key on, then 12 volts while running. The replacement alternator shows a constant 10.5 volts with key on and while running, any ideas? I'm no electrical guru haha
Thanks!
Click to expand...
Where are you taking your voltage reading? At the battery in the trunk or at the alternator? What size wire did you run from the battery to the starter and what size charging wire back?
 
Your voltage readings are all out of whack but it's not charging. Check what it is running at the alternator output stud. "Rev" the engine good to make sure it excites.

A running system should be 13.8--14.2 running fast enough to charge, with the engine warm and the battery "normalized" after starting. Regulators are temp compensated.

Low end for "me" is 13.5, high end is 14.5

A fully charged battery with no surface charge should be 12.6, that is, say, after sitting all night and no start/ headlights load
 
^ you are right, I had my numbers backwards, 12 with key on and 14 running with old alternator.

Fast, I'll have to check where I'm taking my voltage, been awhile lol. The cable size from battery to starter is pretty big, I believe it is 1/0, bout the size of a quarter. I had problems with that before so I got the biggest cable I could from battery warehouse. The charge wire i think is 8 gauge and doesn't go all the way back to the battery, it's on the power lug at the starter selonoid where battery power wire is
 
You must log in or register to reply here.
-

Back
Top