Hi, need some help. I've put in 3 new batteries and change the alternator 3 times and my battery keeps draining within 3 days. I put a new alternator and battery and while the car is on I remove the positive cable on the battery and the car turns off. Any suggestions would be greatly appreciated.

 

What is the voltage on the battery when the car is off? What is the voltage on the battery when the engine is running?

 

The battery is currently drained. I have to re-charge it. What reading should I have while on and off?

 

A good battery will have 12.6V when the car is not running. When the car is running, the battery should have around 14V.

 

Your car should have a signal wire to the alternator (maybe labeled "C"??)

It's supposed to work like this:
If the battery voltage is good, and the ELD is not measuring "much" electric load, then the ECU will connect that signal wire to ground, which tells the alternator to shut off.

However...
If that wire is worn through & shorting to ground, THAT will make the alternator shut off without the ECU "giving that command". Same thing will keep happening with new alternators.

So check your wiring harness to the alternator. Pinched a wire under a bracket somewhere? Rodents chew through the insulation?

 

1. Honda's utilizes a dual mode charging system to increase fuel efficiency and reduce drag on the engine on start-up. The ECM/PCM determines charging based on info. from the ELD. During heavy load, the ECM/PCM can set charging voltage for high output (~14V - 15V). During light load and start-up, the ECM/PCM sets charging voltage for low output (~12 - 13V).

Most previous generation Hondas had alternator/voltage regulators which utilize five terminal wires: Ignition (IG), Control (C), Field Reference (FR), Battery (B), and Lamp (L). The wires between the alternator's voltage regulator and PCM are the C, FR, and L wires. The ECM/PCM can control charge modes (high or low output).

The ECM/PCM will not shut off the alternator.

2. The issue may be due to excessive parasitic draw. This video shows how to narrow down the problem area.

 

For info. only: If under-dash Fuse No. 4 (7.5a) was blown or there was an issue with IG wire (Blk/Yel wire), then the alternator won't charge. Fuse No. 4 and the IG wire supplies the ignition input that turns on the alternator/regulator assembly.

 

Thank you all so much! I'll follow these steps!