Parasitic Discharge

2022 RAM 1500
86,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
Avatar
XRIGHTOFFTHERIPX
  • MEMBER
  • 1 POST
My truck has recently developed a parasitic battery drain. The truck runs and drives fine once started, and the alternator seems to be charging (around 13.8–14.0V while running). However, when the truck is shut off, the battery voltage drops steadily and the truck won’t restart after sitting for a short period.

Using a multimeter, I measured a 3.5 amp parasitic draw with the truck shut off, which is way above the normal spec (
Aug 29, 2025 at 6:49 PM
Advertisement
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,855 POSTS
Yep, 3.5 amps is way above normal. Start by opening the door and closing the latch manually. Then let the truck sit for 45 minutes, then pull fuses one at a time until the draw drops to a normal amount, 20-50 milliamps (0.02-0.05). This will tell us which system is misbehaving. Also, check the obvious stuff like a glove box light, power mirror switch stuck. Also, with the engine cold see if the AC clutch is warm, this will tell you the compressor relay is stuck on. Please go over this guide to help as well.

https://www.2carpros.com/articles/car-battery-dead-overnight

Make sure to open the door latch before you try and close it. Please let us know what happens.
Aug 30, 2025 at 9:53 AM