I have a battery drain issue with my Duster that I can seem to figure out. I don't see how the drain could be anywhere outside of the trunk which is wired like the picture below. The last 2 times I have had a chance to mess with the car (7hrs away) I have had a dead battery. The first time I believe I left the disconnect on and probably have a drain up front somewhere, no big deal. We charged the battery and ran the car for a while. Disconnected the +battery cable from the battery when we were done. Next start was great, spun it up fast. Let it sit overnight with the +batt cable connect but the disconnect definitely shut off and it was dead the next morning. I just don't see what it could be. Test light between the +batt and post with the switch on shows a drain but I cant find anything outside of the disconnect/battery/alt relay with power when the switch is off, yet it still killed it. What am I missing??

Also, new optima red top, new 60A toyota alt, cole hersee disconnect and continuous duty relay.Thanks in advance

Second question. I have the alt sensing wire wired to my main power distribution points up front and my volt gauge to the same point. At idle the gauge shows 15-16V. I have a new 60A toyota alternator and see 15-16V with only the ignition, fuel pump and fans on. Is this normal?

Looks like it could be that 75 amp solenoid if thats what it is. It's powered all the time maybe shorted inside.

take a voltage checker at each terminal when you have the switch in the OFF position...

a quick check with the test light showed voltage at the battery side of the disconnect and on the battery side terminal of the alt feed relay with the switch off. I didnt check the alternator side of the 75A relay because that is a direct feed to the alt and shouldnt drain the battery, it was more of a safety thing.

If that relay was internally shorted, could it short to the small relay terminals and to ground? If it did that I guess it could back feed to the small terminals on the disconnect and then my fuel pump relay would be an additional, but small, drain. I really think I checked for voltage on the small hot side of the 75A relay to make sure the disconnect was working properly and confirmed that it was, but I did all of this a few weeks ago when I was back down in NC so I may have missed/forgot something.


With the switch on, that 75A relay is a constant drain and I need to figure away around because I dont want to have to hit the disconnect everytime on my street car. Maybe I'll just bypass it and watch where I'm wrenching when near the alternator.

not sure exactly what you're doing there or what the two +/- "terminals" are in the upper left but as i see it the 75 amp relay coil is energized all the time the battery switch is on. also i don't know if that one wire from the alternator is the sense wire or the ignition wire for the alternator. if it's the ignition wire the one i checked the other night was pulling 20 milliamps. either or both of them would probably kill the battery if left energized. i would just run the alternator output to the starter feed and ditch the relay.