Battery always dead

[DAVID GAGNARD]

This is a shot in the dark, but if you have an MSD ignition and if the main feed wire (heavy gage red wire) is not fed through a relay or other switched source. The MSD will drain the battery in about a week even if the control wire from the ignition switch is off. I use a battery disconnect switch because of this and have used the same Optima battery now for 5 years with no problems even after letting it sit for 6 months with out charging.

Could be,cause I'm runing an MSD system in my car, never thought of that.........I just disconnect the battery when I know I'm not gonna use the car for more than a week........

BTW: my Optima battery is 6 or 7 years old....I just put the positive cable back on and it fires right up, haven't charged the battery is at least 5 years............

David

[HI Cobra]

David - that is exactly what I do with my CR, and get the same results.

[Blas]

My car can sit for weeks without the MSD draining the battery. My MSD main feed comes straight off the hot side of my main circuit breaker.
I would suggest you look further into this if you think your MSD is your problem...or just keep using the battery cut-off switch...

[DAVID GAGNARD]

I don't know if it is the MSD or not, mine is wired per the instructions, did it too many years ago (at least 10 years) to remember how.....

At the time, I also changed my dash panel/gauges (65 Mustang fastback) from the factory panel to a custom made panel with analog gauges, also added a JVC radio with a clock and the memeory thingy for the radio settings, that's when it would run the battery down, takes at least 2 weeks......

I chased down some stuff and found one thing and fixed it, but it kept doing it, so it is too easy just to pull the positive cable off the battery, so, being a lazy fellow, that's what I started doing and since being in the habit, it's no problem for me, but still didn't fix the problem, and after 10 years, it'll probably never get fixed correctly by ME............

David

[Blas]

I'm sure all have you have searched for the source of this issue on your cars. I would probably approach the issue in the following ways.
Have you ever just disconnected the MSD box for the usual period of time required to drain the battery? Same thing for removing one fuse at a time for the same duration. At lease you would determine the circuit the drain is assosiated with. The most common things I've seen are: a bad cell in the battery, improper charging because of a faulty voltage regulator, bad alternator, improper cable sizes, wrong location for wire connection from voltage regulator...and the biggest electrical problem...bad/undersized grounds. Hope you find it or a good work around...

[JohnM]

A quick update. I do have an MSD ignition, and a battery disconnect. I have the radiator fan on direct feed so that it can run when I put the car away in garage after driving with the battery disconnected. The fan takes alot of juice to run but doesn't run very long after the car is put away..just 2-3 minutes

The only other direct wire is the clock with it moving second hand.

I will look into this MSD situation

thanks

John

[Cobra #3170]

Originally Posted by Blas

My car can sit for weeks without the MSD draining the battery. My MSD main feed comes straight off the hot side of my main circuit breaker.
I would suggest you look further into this if you think your MSD is your problem...or just keep using the battery cut-off switch...

Digital Fluke shows about 350 ma from battery to MSD with switched lead off.
Maybe I have a bad 6AL but this is the second box and it still does it.

[JohnM]

In regards to the eletric cooling fan....don't most new production cars have electric fans that can run at any time?

I have a thermostat probe in the radiator that comes on at about 190F + or -

I have cast iron heads that I understand continue to transfer heat once the engine is shut off....my water temp guage goes up when the engine is off for a few minutes and fan is not running

looking forward to hearing your thoughts

John

[Rick Parker]

I disagree with the MSD theory. The small "Switched" 12 volt wire is what initiates current draw within the unit. I would look at the voltage regulator or a tired battery with bad cell(s).

[1bad66]

I am running a 1 wire GM alternator and at first I had the "excite" wire hooked to a constant power source and sure enough my battery was dead every 4th or 5th day. Finaly hooked it to a switched source and problem solved.

[DAVID GAGNARD]

Originally Posted by JohnM

In regards to the eletric cooling fan....don't most new production cars have electric fans that can run at any time?

I have a thermostat probe in the radiator that comes on at about 190F + or -

I have cast iron heads that I understand continue to transfer heat once the engine is shut off....my water temp guage goes up when the engine is off for a few minutes and fan is not running

looking forward to hearing your thoughts

John

The cars that come equipped with electric fans are run by thermostat/computer. Most cars have 2 electric fans for a reason. One is run strictly by the engine temperature and the other is also run by engine temp, but also has an override that switches it on and keeps it on as long as you have the A/C on....With the A/C on, you always have one fan running and the other will cycle on/off according to the water temp........they both will shut off when you turn the ignition switch off.

Regardless of the heads,be they aluminum or iron, once you shut off a fully warmed up engine, your water temp gauge will show some increase in temp, mine usually about 5 to 8 degrees over the running engine temp, that's normal, running you fan with the engine off does nothing but cool the water in the radiator, does nothing for the water in the engine itself and will not cool the engine, to do that, you would have to be circulating the water thru the engine via. electric water pump......

David