battery death by MSD?
 

Does anyone have any experience with an MSD 6al draining the battery?

I installed a 6al on my 84 Mustang and it seems to perform fine. Three days after the install my battery was dead. I replaced the battery and now three days later my new battery is dead. Could it just be a coincidence that my charging system started having problems at the same time I did the MSD install?

Any help is appreciated.

Could be your alternator too. If you want to experiment, remove the large charging cable from the alternator and let it sit for 2 days and see if it drains. If it doesn't, pull the main 12v feed to the MSD and let it sit whichever eliminates the loss of charge is it.

Thanks. When the new battery went in I read voltage at the battery with the car running and it was about 14 volts would this not indicate that the alternator and voltage regulator are working OK?

If you put a meter across your battery while the motor is running and you see voltage higher then 12.5 you're charging system is working fine. Normally you'll see in the 14.something range.

Thanks for the info, I had already checked at the battery to see if my alternator was working and it was, the next time I checked it wasn't.

I've given up and taken it to a shop where they tell me there is something shorting out the alternator...they replaced it and burned out the new one.

They are looking for the short as we speak.

My MSD 6al drains my battery down if it sits for awhile without being started. I am sure it is the MSD because if i disconnect the hot wire to the MSD box when it sits for awhile the battery holds the charge fine. But if i leave the hot wire on there after a week or so its dead as can be.

I dont think it is the msd. I leave mine all hooked up and dont drive it for 2 or 3 weeks at a time, and it cranks immediately every time.

I don't think it's the MSD either. I barely drive my LX (maybe 300 miles a year). I only start it to move it around. I start it maybe once every two weeks.

Not once has the battery drained.

OK, my problem was a short in the signal wire from the ignition switch to the voltage regulator. So, the alternator was not getting the message to start charging the battery when the car was running.

I couldn't locate exactly where the short was so I ran a new wire from a switched source to the voltage regulator, so far so good.

While trying to figure this out I did have a conversation with the MSD help line and was told there is a posibility of a bad capacitor in the box that could cause a voltage drain to the system.

Yeah, they use elctrolytic capacitors and they can go bad. If you have a 6A and their not going to repair under warranty, you can take the back cover off as see the capacitors - the electrolytics often leak and go bad. Not hard to replace, just have to have the millifarad and voltage rating to replace it. I have a 6M in my boat that wnet bad - it's potted in expoxy, so no repairs possible.