[DeTomaso] Why Is My Battery Discharging?

thomas thomas at hax.se
Wed Dec 24 03:07:41 EST 2014


Probably one or more bad diodes in the alternator.

Cheers,
Thomas


> 24 dec 2014 kl. 03:03 skrev Edracers--- via DeTomaso <detomaso at poca.com>:
> 
>   Aloha
> 
>       The battery dying problem was solved. The mechanic replaced the
>   alternator and regulator. Why it sucked the battery dry overnight is
>   mystery to me. But I never understood amps, watts, volts, etc anyway.
> 
> 
> 
>   Mahalo (thanks) for the help.
> 
> 
> 
> 
> 
>   Ed Kemper
> 
> 
> 
>   In a message dated 12/18/2014 4:11:40 A.M. Hawaiian Standard Time,
>   Larry at ohiotimecorp.com writes:
> 
>     Hi John,
>     If you knew me better (and you should:) you would know that I hold
>     animals
>     far above most things I love. Certainly most people! I keep telling
>     people
>     there is a reason I live in the woods...
>     So I grant "The DVM" the power to measure voltages with "a" DMV. I
>     hope you
>     are as forgiving to me when you learn what testing I am doing in VM.
>     Larry (not nutz, never been tested) - Cleveland
>     -----Original Message-----
>     From: John Donahue [mailto:demongusta at me.com]
>     Sent: Wednesday, December 17, 2014 7:47 PM
>     To: Larry - Ohio Time
>     Cc: detomaso at poca.com
>     Subject: Re: [DeTomaso] Why Is My Battery Discharging?
>     Been following this discussion, and could not resist to comment on
>     the first
>     sentence  - 5th paragraph (I think) - since I am a veterinarian
>     (DVM) - and
>     have been known to be "sensitive". LOL
>     On Dec 14, 2014, at 5:05 PM, Larry - Ohio Time
>     <Larry at ohiotimecorp.com>
>     wrote:
>> 
>> 
>> Hi Ed,
>> 
>> Lots of very good advice, but I do things just a bit differently
>     (that
>> should not be surprising).
>> 
>> I have an old "trouble light" that I have modified. Cut the 110vac
>     end off
>> and install two larger alligator type clips on the wire ends. Now
>     change
>     the
>> light bulb to a 12 volt model. You can find them at RV stores.
>> 
>> Now hook this between the battery post and the removed battery
>     cable, like
>> the others have said. If there is a load (drain) the 12 lamp will
>     light
>     up.
>> Now take this light to the fuse box as others have told you to do.
>     When
>     the
>> light goes out you found the problem. You can get good at
>     determining the
>> amp draw by how bright the lamp is after a wile.
>> 
>> You are going to need a light anyway :)
>> 
>> The problem with a DVM measuring voltage is that they are very
>     sensitive.
>     I
>> have measured voltage from the positive post to the top of a dirty
>     battery
>> case.
>> 
>> An Amp meter is the way to go but they can be costly (I have two
>     Sun units
>> for sale) and then you need to crawl out from under the dash, walk
>     to the
>> battery and bend over to read it. That takes me about 20 minutes
>     each
>     time.
>> 
>> Thinks to remember:
>> 
>> If you open a trunk, hood, door, glove box and a light normally
>     comes on
>> this will look like a drain (short) when you open them during
>     testing.
>> 
>> The battery is draining when the car if off and key is out, so
>     look at the
>> things that work then, horn, lights ect.
>> 
>> You do not want to kill your new battery so do not leave it hooked
>     up
>     until
>> you find the problem. It can also be a fire safety problem should
>     the
>     drain
>> turn into a short.
>> 
>> In Pantera's I have found bad horn relays, voltage regulator and I
>     think a
>> back up switch on the ZF that have done this.
>> 
>> Larry (sparks) - Cleveland
>> 
>> 
>> -----Original Message-----
>> From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of
>     SOBill via
>> DeTomaso
>> Sent: Saturday, December 13, 2014 7:24 PM
>> To: detomaso at poca.com
>> Subject: [DeTomaso] Why Is My Battery Discharging?
>> 
>> 
>> Ed,
>> 
>> At http://www.panteraplace.com/Electrical/Power%20Distribution.pdf
>     you
>> will find a diagram showing the electrical power distribution on
>     the
>> Pantera.
>> This diagram is the Big Picture based on a stock Pantera
>     electrical
>     system
>> and was made at the suggestion of and with the help of Lee
>     Farrell.
>> 
>> How to find out why a battery is discharging?
>> 
>> Disconnect the negative battery cable. Now the battery can not be
>> discharging into any circuit in the car. Measure the battery
>     voltage with
>     a
>> 
>> multimeter which can read to at least 0.01 volts. Such meters are
>     readily
>> available and are quite inexpensive. If your battery voltage is
>     slowly
>> decreasing,
>> the battery is being discharged. What does "slowly deceasing"
>     mean? My
>> battery voltage did not vary by +/- 0.01 volts measured over 5
>     minutes.
>     If
>> your
>> battery voltage is slowly decreasing when the battery is not
>     connected  to
>> any load, you have a bad battery.
>> 
>> If the battery is good, why is it discharging?
>> 
>> Reconnect the negative battery cable to the battery. Measure the
>     battery
>> voltage. If the battery voltage is decreasing, the battery is
>     discharging
>> thru a load in the car. Looking at the Power Distribution
>     Diagram. How
>     can
>> the battery discharge? The battery could discharge thru the
>     Alternator,
>     the
>> 
>> Ignition Switch, the Headlamp Switch, or Fuses 7,8, or 9. Since
>     the
>> Headlamp
>> Switch is OFF, and the Ignition Switch is OFF, the battery could
>     only
>> discharge thru the Alternator or Fuses 7, 8, or 9. Since the fuses
>     are
>> relatively easy to get too, pull Fuse 7, If the battery voltage
>     continues
>     to
>> drop,
>> replace Fuse 7 and pull Fuse 8. If the Battery voltage continues
>     to drop,
>> replace Fuse 8 and pull Fuse 9. If the battery voltage continues
>     to drop,
>> replace Fuse 9. Unless there is more than one problem, we have
>     eliminated
>> the
>> circuits associated with Fuses 7, 8, 9 as the source of the
>     problem. On
>     the
>> assumption that we have a single circuit causing the problem, I
>     recommend
>> pulling and replacing fuses one at a time. It is no fun to wind up
>     with a
>> pile  of poorly marked fuses to sort out against a diagram. A more
>> scientific
>> approach, which accommodates multiple causes for the problem, is
>     to pull a
>> fuse,  mark it as to location, and do not replace the fuse until
>     we have
>> solved the problem. Do it which ever way makes the most sense to
>     you.
>> 
>> The next item to test would be the Alternator, but, since fuses
>     are easy
>> to access, pull fuses one at a time and recheck the battery
>     voltage.  If
>     you
>> 
>> pull a fuse and the battery voltage stops dropping, you have
>     found  the
>> circuit that is draining the battery. If you have tested all the
>     fuse
>> circuits
>> and the battery voltage is still dropping, the only component left
>     is  the
>> alternator.
>> 
>> To this point, we have had life fairly easy and we should be done
>     is less
>> than one hour. Life, unfortunately, is going to get a little less
>     easy. We
>> must  get to the Alternator.
>> 
>> How to find out if the drain is in the Alternator?
>> 
>> Disconnect the negative battery cable from the battery. At the
>     rear of the
>> Alternator remove the Big Black wire and be sure it does not touch
>     the
>> chassis.  Reconnect the battery negative cable to the battery. If
>     the
>> battery
>> voltage continues to drop, the problem is not in the alternator.
>     If the
>> battery voltage stops dropping, the diode pack in the alternator
>     is the
>     most
>> 
>> likely problem. Any auto electric shop can easily fix this
>     problem.
>> Disconnect the negative battery cable. Reconnect the big black
>     wire at the
>> alternator. Reconnect the battery negative cable to the battery.
>> 
>> If you have done all of these tests and the battery voltage still
>     continues
>> to drop, something quite strange is happening IF YOUR CAR IS
>     STOCK. If
>> your is  not stock, disconnect whatever is not stock and see what
>     happens.
>> 
>> This all sounds quite complicated, but it really is not. Look at
>     the
>> diagram, think of what you eliminate when you pull a fuse. There
>     is no
>> magic: No
>> Fuse = No Drain. The problem can be found.  Let me know what you
>     find in
>> any case.
>> 
>> SOBill
>> 
>> The main  thing is to keep the main thing the main thing.
>> Do the best you can with what  your have where you are.
>> Have fun today!
>> SOBill
>> 
>> 
>> 
>> 
>> 
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