[Shop-talk] electrical problems with truck

[john niolon]

Took the truck (53 ford f-100) out for a drive yesterday…first time since the 
Grand Nationals (I’ve been busy) Ran great for about 30 minutes with a couple 
of stops during the ride… each time it started right and showed no problems. 
Electric fan and a/c running the whole time As I pulled out of one business and 
headed home the truck stumbled and died..almost like it was out of gas… ( had 
over a half a tank) I pulled into a business and tried to start it and all I 
got was a ‘click”. Dash Volt meter read about 11 volts with switch on and 
dropped to zero when hitting the starter. Waited about 10 minutes and it 
started right up… got it home, shut it off and same thing “click”.

Battery has been on a battery tender full time since May and showed 13.7 volts 
on VOM connected to the battery before the ride.

Battery is 2 years old Everstart Maxx27 800 CCA …  

Davis DUI ignition (which could have quit when battery voltage got low)

All cables are new with 1/0 welding cable for starting circuit and battery 
ground to frame
engine to frame, frame to cab and frame to bed are all #4 wire to bare metal 
connection points with dialectic grease.

At first glance...when running,  the volt meter on dash shows over 13 volts so 
I think alternator is good 

did a load test with a H.F. (100 amp) load tester showed battery dropping to 10 
volts during 10 second load... recovered to 12. 

Put truck up on stands and dropped battery (under cab)  checked all cables and 
connections from battery to starter including solenoid and ground connections.
all tight, no corrosion on terminals and  cells full.  this truck finished last 
year and everything is new.  Starter solenoid is a Cole-Hersee 200 amp 
continuous draw solenoid.

Starter is new last year and 6-7 inches away and below headers so heat soak 
isn't causing the problem

Set it back down and charged it for 30 minutes at 10 amps... battery showed 12.9 volts..  started ok and put meter on alternator
terminals... alternator putting out 14.5 - 14.8 volts...  varies a little with engine speed.... so alternator is good I think.

 I did a load test again.,.. idle voltage reading 12.9 volts on two different fluke meters... and during the load test it dropped to 12.3 then recovered to 12.7...so I'm 
assuming the battery is good, it was just low before the first load test.

here's an odd thing.. I have a 12 volt terminal on the right frame rail that powers the elec radiator fan, tilt hood motors and trinary switch

with the a/c on, headlights on and elec radiator fan running (as much load as I can put on it)... the alternator o/p at 14.5 volts, the voltage at the terminal on rail reads 11.5 volts.  The terminal is 4' 
from battery and fed with #4 stranded wire.

that's about all the detail I can give you... any ideas why it stalled and quit..???   and why the terminal point only reads 11.5 versus the 14.5 at the alternator.

I'm 
at the wall

thanks
john
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