Charging question
Thread Starter
On The Tree
Joined: Nov 2014
Posts: 102
Likes: 0
From: NW Florida
Charging question I've got a few thousand miles on my swap now (see see sig for details) and noticed that when I start the truck it charges up to ~14.5V right off but will drop to as low as 11.0V when idling, especially noticeable with the headlights on since they dim quite a bit. When driving it charges fine and after a couple minutes dropping below 12V when idling at a stop light/sign the alternator kicks in and the gauge shows over 14V for a while. It hasn't died and hasn't failed to start or anything but I'm wondering if there is something I should look at to prevent it from dropping below 12V?
Thanks
Thanks
TECH Fanatic
Joined: Dec 2017
Posts: 1,467
Likes: 265
From: Bossier City, Louisiana
I'd get your alternator tested at an auto parts store - usually, a free test. Might be a bad voltage regulator inside your alternator. Is the alternator belt tight? Are your grounds good . . . big fat ground cable between the battery and the alternator mount frame?
Are your voltage readings taken at a dash gauge or measured at the battery with a known good multimeter and the engine running?
Rick
Are your voltage readings taken at a dash gauge or measured at the battery with a known good multimeter and the engine running?
Rick
If, as a part of the swap, accessories were mixed and matched, you have a pulley size combination that is resulting in turning the alternator a little too slowly at idle. The fact that voltage picks up with rpm seems to point to this. Perhaps as simple as a pulley change to speed up the alt a bit.
Thread Starter
On The Tree
Joined: Nov 2014
Posts: 102
Likes: 0
From: NW Florida
If, as a part of the swap, accessories were mixed and matched, you have a pulley size combination that is resulting in turning the alternator a little too slowly at idle. The fact that voltage picks up with rpm seems to point to this. Perhaps as simple as a pulley change to speed up the alt a bit.
Rock
I have a crate LS3 with Corvette main pulley, and an Escalade 145A alternator. With headlights, stereo and full A/C on (dual cooling fans) mine sits at 14.2V at 675 rpm idle. Just as a data point.
