A typical car battery has about a 40 amp hour rating. If your battery is fully charged, a 3.8A load would take at least several hours to drain the battery. To drain it in 20 minutes you would need current drain in the 40A ballpark, which would more than likely create heat/smoke/melted wires.
I would look into the charging system to make sure the battery is getting fully charged. Check the voltage on the battery with the engine running. Also, try turning on lights & wipers with engine running to make sure the voltage holds.
It is possible to have a weak alternator that can put out sufficient voltage with a small current load, but will drop off with heavier load such as headlights.
Quote:
Originally Posted by binkoba
I have a random battery drain issue I am trying to fix.
The car can sit, sometimes for days and start right up. Other times I park it and the battery is down to 8 volts in twenty minutes.
Here is what I have checked.
1. It is a new battery, plus I have tried three other batteries
2. Amp meter in circuit sometimes shows .2 amps to almost nothing.
3. With the main lead to the engine bay disconnected the car does not go flat.
4. removed and tested the alternator - It passed. Reinstalled.
5. figured it was the starter, replaced.
6 reassembled car moved car, - battery flat after 30 minutes.
Now with the car parked, key out, doors closed, lights off the car is pulling 3.8 amps.
Grrrrrrrrrrrrrrrr..
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