Author Topic: flat battery  (Read 2264 times)

flat battery
« on: October 28, 2007, 08:55:13 PM »
Hi all. My question relating to my 61. I had a flat battery  requiring a jump start. I then took the car out for a half hour drive before turning the motor off. I waited 2 mniutes and turned it on again. It started straight away. Voltmeter read 12.2 volts, up to 12.7 with revving.  Next day the battery was completely dead-reading 0.12 volts.[ i.e one eighth of one volt.]   Now this is a top of the line Bosch battery that is 4 months old in a car that gets driven every week. Could not find any radios ,lights, clock left on etc. My previous battery also lasted 4 months and in neither case were there any dramas till they went kaput. Is the simple test of re-starting the car 2 minutes after a long drive enough to say that the generator is ok or should this be tested. Not sure how to do this with the volt meter. I have heard you need to disconnect 2 wires and create a bridge across the 2 terminals.  Thank in anticipation, JOHN.

Offline Fred Zwicker #23106

  • Posts: 616
  • 1930 LaSalle Conv. Coupe - Restored
  • CLC Number: 23106
  • Name: Fred Zwicker
Re: flat battery
« Reply #1 on: October 28, 2007, 10:03:33 PM »
I would also consider investing in a Battery Tender and  use it faithfully every time you park the car, even overnight.  This might solve your problem temporarily until you figure out what is wrong.  Hopefully no shorts.  Sometimes you can detect a short by turning off everything and then disconnecting the battery cable.  Then when reconnecting the cable, look for a spark.  If even a small spark, you probably have a problem.  If a big spark, you could have a big problem. 

Fred
1930 LaSalle Convertible Coupe, CCCA Senior
1939 LaSalle 2-Dr. Conv.  CLC Senior in 2008
1940 Cadillac Series 75 4 Dr. Convertible
1947 Cadillac Series 62 Convertible Coupe
1948 Cadillac Convertible - modified by Holly (driver)
1966 Cadillac DeVille Conv. Restored - Red
See Pictures at www.tpcarcollection.com

Offline Glen

  • Posts: 2789
  • CLC Number: 727
  • Name: Glen Houlton
Re: flat battery
« Reply #2 on: October 29, 2007, 03:01:00 AM »
I would also consider investing in a Battery Tender and  use it faithfully every time you park the car, even overnight.  This might solve your problem temporarily until you figure out what is wrong.  Hopefully no shorts.  Sometimes you can detect a short by turning off everything and then disconnecting the battery cable.  Then when reconnecting the cable, look for a spark.  If even a small spark, you probably have a problem.  If a big spark, you could have a big problem. 

Fred

If you have the original type clock you should tap the connection once to let the clock rewind then tap it a second time to check for a spark. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

Doug Houston

  • Guest
Re: flat battery
« Reply #3 on: October 31, 2007, 12:21:42 AM »
South Paw put his finger on nit. Your generator isn't putting out enough voltage to charge the battery when the engine is running. Either the generator regulator is set too low, or is defective, or the generator isn't working at all. A good electrical shop should be able to test the charging system and find the trouble.

Re: flat battery
« Reply #4 on: October 31, 2007, 12:50:12 AM »
Thanks for the input guys. I'll mosey on down to my friendly auto elec. and keep you posted on the result.   Cheers, John.

Offline homeonprunehill

  • JIM CLC #15000 THOMAS 1938 La Salle 5027
  • Posts: 655
Re: flat battery
« Reply #5 on: October 31, 2007, 02:09:13 AM »
Thanks for the input guys. I'll mosey on down to my friendly auto elec. and keep you posted on the result.   Cheers, John.
quote

10-30-07
John , Any good auto-parts store should be able to check the electrical system in your car at no cost, if you buy the required part.
Good Luck,JIM
USED,ABUSED AND MISUSED CADILLACS AND LA SALLES

Re: flat battery
« Reply #6 on: October 31, 2007, 07:58:54 PM »
South Paw put his finger on nit. Your generator isn't putting out enough voltage to charge the battery when the engine is running. Either the generator regulator is set too low, or is defective, or the generator isn't working at all. A good electrical shop should be able to test the charging system and find the trouble.

That may be true Doug, but that doesnt explain why it is killing battery and the fact that it goes back down over night means something is draining it. 

Doug Houston

  • Guest
Re: flat battery
« Reply #7 on: October 31, 2007, 08:09:18 PM »


That may be true Doug, but that doesnt explain why it is killing battery and the fact that it goes back down over night means something is draining it. 
[/quote]

That's also a factor, but, from the information in the earlier posts, the system voltage is not high enough to charge the battery with the engine running. Indeed. there may still be leakage current being drawn from the battery while the car is sitting idle. That hasn't been established yet by measurement. He's going to have to get the generator working properly first, and then, chase any other problems that may be present.

 

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13