battery dis-charge and short

[Erik]

my red top optima battery recently discharged to the point of not being able to start the car - '74 US coupe. I recharged it and reinstalled it. Then I pulled the post connection when I wasn't driving the car, - most of the time these days unfortunately, and reconnected when I wanted to start up.

Sort of a pain, but worked fine while I hoped to find the time when I could get a friend to help me chase down what I assumed was a short. Haven't had time to yet, but now the sunroof switch and the A/C are both nonop. Check of the fusebox revealed nothing. Everything else seems to work.

Any suggestions?

Also, anyone ever heard of the optima not charging fully due to difference in internal resistance causing the voltage regulator to set the recharging rate lower than for a traditional lead-acid battery?

 

[Arde]

Erik, I chased an intermittent short for 3 weeks that only happened at 80 mph. That familiarized me with the electrical system, so I'll be glad to help in exchange for expresso and croissants in Los Gatos. For mine I used a small 12V bulb wired with clips that are easy to connect in parallel with the fuse. The bulb comes on the moment the fuse blows, and presumably you can figure out what else was going on at that time to cause it.

If the load is not enough to blow the fuse but still drains the battery, you can use the same bulb on clips but this time you remove the fuse. If the bulb lits with engine and all systems off, you have a drain on that circuit. I had one of those and I traced it back to the trunk light staying on with the trunk closed.

 

[Erik]

Arde, that sounds like a great simple diagnostic tool :idea:, and I have to say the price is right on possible assistance too! Now if I could just get my mechanic to take coffee and pastries as payment....

Will message off-board re possible times. Look forward to seeing your coupe again too, - gotta' love the verona

 

[Honolulu]

besides the trunk light

check that the glove box light goes off when it's supposed to.

Now tell me, does the refrigerator light REALLY turn off when you close the door?