Something is draining the battery....

[Robert O.]

[Thomas H.]

Re: Something is draining the battery....

If the MSD is wired to constant 12v instead of switched 12v, that could be your problem right there.

I like to troubleshoot battery drain issues by looking at current rather then voltage. If your meter can be configured to read current (at least 10 amps), I would pull all of the fuses, install the meter between the battery + terminal and the positive cable. With the fuses out (and the MSD power disconnected) you shouldn't see any current draw. Put the fuses back in one by one and watch to see which circuit starts drawing current.

I'm sure others will have more suggestions. Let us know what you find.

Tom

[Chuck G.]

Re: Something is draining the battery....

Back in the day, one of the more common causes of battery drains on 68-69 cars was the fact that owners would leave the override switch for the windshield wipers ON. This is the switch located under the steering column with the large black knob.

[Rich G.]

Re: Something is draining the battery....

Make sure the glove box lamp goes off when the door is closed. The original owner of my 68 stated he had this problem when the car was new. There might even have been a TSB relating to proper adjustment of the bracket that holds the switch.

Also, as stated above, you have to re do you tests measuring current, not voltage. And wiper over ride is the usual suspect, too.

Rich

[Robert O.]

Re: Something is draining the battery....

Thanks, Tom... yes, the MSD main power lead is wired to a direct hot; and the lighter power lead is hooked to a switched hot. i do have a meter capable of 10 amp and will try your tests today.

[Robert O.]

Re: Something is draining the battery....

thanks, will check that.

[Robert O.]

Re: Something is draining the battery....

will start with the alternator test since i spent considerable time yesterday going over the MSD. BTW... this car has the original date-stamped alternator which was mfg in August 1967... still works!

[Robert O.]

Re: Something is draining the battery....

will check both items. got to find this.. i could just use a battery disconnect switch, BUT... I want to know what the culprit is...

[Jim T.]

Re: Something is draining the battery....

Robert I have a 1968 Corvette and I believe your problem with your Corvette just sitting and not driven that somehow the wiper switch could of been pushed on. Without starting your 1968 Corvette if this has been done will drain our battery. I know because I discovered this problem in my 1968 about 30 years ago. Has not happened since because I know what happens if the switch is accidently turned on without starting my Corvette and cycling the windshield wipers to stop the drain.

[Robert O.]

Re: Something is draining the battery....

Thanks a bunch, Jim. When i first started troubleshooting this problem several days ago (cant put the whole day into it) the first thing i did was remove both seats and the steering wheel so i (250#) can get up under the dash. That is the first time i saw this big black knob. i turned it and the wipers came on. I have not had a chance to evaluate the change it may have made. I will get back to it today and update everyone this evening. regards

[Robert O.]

Re: Something is draining the battery....

Thanks, Tom

The MSD 12 ga red wire is directly fastened to the hot side of the horn relay. I don't like that so i am going to take it through the firewall and connect to the fuse panel. will let you know whatever i find... hopefully soon

regards

bob

[Robert O.]

Re: Something is draining the battery....

Hi Chuck, I "discovered" the black knob and turned it... the wipers came on. Have never used the wipers so did not know. not sure it was the problem.. back to it today. will update hopefully this evening.

regards,

bob

[Robert O.]

Re: Something is draining the battery....

Rich, i checked for the glove box lamp and found nothing but the lens.. the wires were hanging loose so that was not the problem. I just discovered the wiper override knob.. turned it and wipers came on. not sure it was problem.. continuing to eliminate possibilities.

i think i fried my ammeter yesterday. it only has 10 amp capacity. i went to ck voltage between batt posts. got a spark... now it wont read amps anymore. will open to see if by some chance it has a fuse...

regards,

bob

[Mark E.]

Re: Something is draining the battery....

Get yourself a clamp-on ammeter. For less than $100, it will make short work of your diagnostics.

[Robert O.]

Re: Something is draining the battery....

Get yourself a clamp-on ammeter. For less than $100, it will make short work of your diagnostics.

Thanks, Mark.

I have been looking at ammeters and did not know if a clamp-on meter would work, or if i need an ammeter hooked in series fore each test...

regards

Bob