Power drain while running

Tiny
1ERALBRIGHT
  • MEMBER
  • 2008 HONDA FIT
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 240,000 MILES
Battery is new and checks out, alternator tested at 14.71 volts, and cables all checked okay between them. A new conveyor belt is taut around the pulleys. Ground wire from car to battery cleaned and tightened. The car starts, but the voltage at the battery leads then drops to 11.26v and eventually the battery dies if the car continues running. My guess is that the starter solenoid is sticking and causing a power drain. Am I far off?
Sunday, March 27th, 2022 AT 10:28 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,635 POSTS
Hi,

You indicated the alternator output was 14.71. How was that checked on the vehicle or bench tested?

If it is dropping to 11.26 at the battery when running, the alternator isn't doing anything.

Let me know how it was tested. If on the vehicle, we need to confirm it is getting power from the battery. If it was bench tested, then I will know the regulator isn't the issue.

If it was bench-tested, I need you to check for 12v at the B terminal and the IG terminal on the alternator. Do this with the key on.

If there is no power to either, check fuse 1 in the under-hood fuse box and fuse 3 in the fuse panel in the vehicle. If the fuses both check good, it is important to confirm they have power. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

I attached the charging system wiring schematic below for your review. I had to cut the pic in half to make it readable but did overlap the two so you can follow from one to the next.

Let me know what you find or if you have questions

Take care,

Joe
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Monday, March 28th, 2022 AT 6:45 PM
Tiny
1ERALBRIGHT
  • MEMBER
  • 16 POSTS
The alternator was bench tested. I put it back in the car, restarted with similar results as before, and let it sit for a few days until time and weather permitted me to follow up with your advice. Tonight, I checked the fuses before the alternator wires, and they were intact. I pulled fuse 3 and put it back in. Turned off the rear defroster before starting the car on a whim. The battery read 14v at the leads and the problem seems to have disappeared.

Thanks very much for your input in any case--it was informative.
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Thursday, March 31st, 2022 AT 9:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,635 POSTS
Hi,

You are very welcome. I'm glad it seems to be working properly now.

Please feel free to come back any time if you have questions. You're always welcome here.

Joe
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Friday, April 1st, 2022 AT 1:17 PM

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