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Author Topic: 1939 La Salle Something draining battery  (Read 183 times)

Offline 39LaSalleCaddad

  • Posts: 28
  • Name: xmatos
1939 La Salle Something draining battery
« on: October 10, 2017, 04:44:31 PM »
Hey folks.

New battery, rebuilt starter, generator and cleaned up connections in charging/starting circuit.

Meter shows that the system is charging.  However, turning the car off and sitting over night something is draining the battery.  No visible lights are on.  Friend recommended recharging the battery then removing one fuse at-a-time and seeing if the battery stops sparking when I connect it.  Then see what is connected to that fuse in the wiring diagram.  It currently sparks considerably when I connect the battery.  I learned it is positive ground and am connecting it correctly.

Just wanted to run this by you guys and see if this is a good way of finding out what is draining my battery.

Thanks!

Offline The Tassie Devil(le)

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    • CLC Member
      CLC Member #18992
  • Name: Bruce Reynolds
Re: 1939 La Salle Something draining battery
« Reply #1 on: October 10, 2017, 05:10:40 PM »
The fact that the terminal sparks when connecting it to the battery, there is definitely a current draw.

Removing fuses is a good idea, but check things like a light being left on.   Not sure if these cars have a trunk light, as these can create a drain.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline 39LaSalleCaddad

  • Posts: 28
  • Name: xmatos
Re: 1939 La Salle Something draining battery
« Reply #2 on: October 10, 2017, 05:24:35 PM »
Thanks Bruce. 8)

Offline bcroe

  • Posts: 2057
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      CLC Member #14630
1939 La Salle Something draining battery
« Reply #3 on: October 10, 2017, 07:30:08 PM »
My recommendation is after shutting down, disconnect a battery post and
connect a small light bulb between the disconnected points.  It will show
any significant drain; you can start disconnecting fuses, etc until it goes out.

Bruce Roe

Offline Paul Phillips

  • Posts: 611
    • CLC Member
      CLC Member #27214
  • Name: P Phillips
Re: 1939 La Salle Something draining battery
« Reply #4 on: October 10, 2017, 07:53:11 PM »
I don't have the exact wiring diagram in front of me, but in general, there is a primary feed to the starter solenoid, with a tap from there that goes to the ammeter.  Other side of the ammeter goes to the voltage regulator, ignition switch & cigar lighter/body lightning, and a feed to the light switch with its integral circuit breaker. If you have a draw with the ignition off, then the problem is more likely to be within one of these branches. This is a stepwise search, as below.

If you can, connect an aux ammeter (VOM type) in the battery primary circuit and see how much current is flowing. Then carefully disconnect the lead to the car's ammeter - if the current flow remains on the aux/test ammeter, the leak is in the solenoid or associated wiring. If there is no current, the leak is in the rest of the circuit. If the latter, restore the wiring on the car ammeter, then disconnect the Bat terminal on the voltage regulator.  If current flow goes away, the problem is in the regulator or generator, if not, you need to look further. Restore the connection on the regulator and disconnect the primary feed to the light switch, probably at the back of the switch with a red tracer. If the current leak goes away, problem is in the light switch or associated, wiring, if no, it is in the ignition/cigar lighter/body feed circuit. Follow the same process to disconnect and isolate each of these branches. When you disconnect the offending circuit, current flow on the aux ammeter will.go away.

Good luck!

Paul

Paul Phillips CLC#27214
1941 60 Special (6019S)
1949 60 Special (6069X)

Offline 39LaSalleCaddad

  • Posts: 28
  • Name: xmatos
Re: 1939 La Salle Something draining battery
« Reply #5 on: October 10, 2017, 08:48:07 PM »
Paul,

That is phenomenal troubleshooting advice. Can't wait to execute and report back!

Javier

Offline Steve Passmore

  • Posts: 4985
  • Name: Steve Passmore
Re: 1939 La Salle Something draining battery
« Reply #6 on: October 11, 2017, 03:03:45 AM »
If your 39 is wired as it came from the factory it would have no fuse box,  If it's been re-wired since and has a fuse box the problem could be anywhere in the altered wiring or a fault with exactly how it was wired. Someone may have wired a system bypassing the ignition switch??
Steve

Offline 39LaSalleCaddad

  • Posts: 28
  • Name: xmatos
Re: 1939 La Salle Something draining battery
« Reply #7 on: October 11, 2017, 06:38:13 AM »
No fuse box. Original wiring. Back to the drawing board I guess.

Offline Bob Schuman

  • Posts: 326
    • CLC Member
      CLC Member #254
  • Name: Robert Schuman
Re: 1939 La Salle Something draining battery
« Reply #8 on: October 11, 2017, 06:55:53 AM »
If the car has its original clock that is connected, and has not been converted to a modern quartz movement, that is a likely source of your current draw. The clock was factory wired to run all of the time, It should not drain the battery overnight, but the clock may have a problem.
Bob Schuman
Bob Schuman, CLC#254
1949 6237X
1951 6137
2017 CT6-unsatisfactory (repurchased by GM)
1948 Olds 98 Custom

Offline Steve Passmore

  • Posts: 4985
  • Name: Steve Passmore
Re: 1939 La Salle Something draining battery
« Reply #9 on: October 11, 2017, 07:09:38 AM »
Good point from Bob, that's the only thing powered all the time, but I would think you would smell a short if the battery drained through it overnight.    The original wiring itself could be the fault. The insulation will definitely be extremely brittle and could be failing somewhere where you can't see it.
You will have to carry out the tests as Paul described and hope if its a fault in the wiring that will be visible.  Usually, only the starter could stand that amount of power drain without melting wires. Even rebuilt ones have been known to be bad? 
Steve

 

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