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Author Topic: Battery gone flat AGAIN  (Read 5337 times)

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Offline 87droptop

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Battery gone flat AGAIN
« on: May 03, 2011, 10:08:29 PM »
Hi All,
since i installed the thermo fan and electric pump I had a problem of alternator not keeping up with these and other electricals  and charging the 470amp battery, so it ran a bit warmer than usual since fan was not pumping fully ( 1968) , and eventually it cut off the fuel pump and stalled... I got a 85amp alternator rebuilt ( the other one was 30-40 amp), got a 680amp battery, went for drive, this time it lasted about an hour, so i thought all is ok, and then, sure enough, it died again, so tow truck it home... not happy... battery was flat, again. I might need check all wiring if i can get my hands on a wiring diagram... and, has anyone had any similar issues? maybe i can sort this out soon and turn up at the bankstown show on may 15...
Thanks Guys.
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Offline Scott

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Battery gone flat AGAIN
« Reply #1 on: May 04, 2011, 08:21:23 AM »
Grab a multimeter and check the voltage at the battery and alternator to see if it's charging when the engine is running.  If the voltage at the alternator is different from the battery by much, something is wrong. The voltage at the battery should also be higher when the engine is running, compared to when the engine is off.

It sounds like it's not charging, which could mean a bad connection somewhere.
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Offline bfit

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Battery gone flat AGAIN
« Reply #2 on: May 04, 2011, 09:58:14 AM »
Voltage at the battery should be 12.7 minimum
with the engine running
Take  engine from idle   to about 3500/4000 voltage should vary  up  a little but not to high 13v  to 13.2v approx
 
 then turn the lights on  high beam, thermos  on as well
 and check again  you can get an  idea how  the  alternator is  working under load

 look for hot joint   this indicates  a bad connection
and extra Resistance will reduce alternator efficiency

 hot  joint can result in a fire and that is real worry


I would suggest a battery isolation switch  I think every vehicle should have one

It is a good Idea to check all your earth straps
Bfit





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Offline 77CVT

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Battery gone flat AGAIN
« Reply #3 on: May 04, 2011, 02:36:19 PM »
:agree:  Hot joints = bad news!

Easy test is to start it, put all the lights\accessories on and disconnect the positive battery cable.  If it dies, coughs, lights dim etc the alternator isn't up to it.
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Offline sirfixalot

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Battery gone flat AGAIN
« Reply #4 on: May 04, 2011, 10:17:52 PM »
As the load current is increased battery voltage will decrease if alternator is not charging. What year wiring diagram?
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