[Shop-talk] electrical problem with truck

Mon Aug 9 14:10:29 MDT 2021

Pat, while the battery was out I checked resistance on all battery, starter and 
ground cables... all read from .003 to .004 ohm resistance end to end

 also rechecked the charging voltage again with engine at 1200 rpm  14.6 
volts... as I increased the rpm the voltage flickered down to 14.3 - 14.4 to  
then
back up to 14.6 as rpm decreased back to 1200

did this both with VOM leads on battery terminals AND alternator terminals

j

----- Original Message -----
From: Pat Horne <patintexas at icloud.com>
To: john niolon <jniolon at att.net>
Cc: shop-talk <shop-talk at autox.team.net>
Sent: 8/9/2021 1:30:34 PM
Subject: Re: [Shop-talk] electrical problem with truck

John,
Check charging voltage @ alternator post, alternator terminal, terminal on 
other end of 1/0 cable, post that terminal connects to. If you can get to the 
conductor in the 1/0 cable, get that too. That should be enough to find the 
problem. 

Peace,
Pat

Pat Horne 
We support Habitat for Humanity

On Aug 9, 2021, at 1:02 PM, john niolon <jniolon at att.net> wrote:

sorry for slow response... helping daughter and sil move...priorities!!!

Monday a.m. report

fresh charge on battery 40 amp for 30 minutes on saturday trickle charger since 
then .. battery voltage 13.4 this a.m. checked with two different meters

hooked up H.F. 500 amp load tester, voltage reading same as VOM at 13.4
voltage at frame rail terminal also 13.4

battery has 800 CCA capacity
started test... over 15 second test the battery slowly dropped to 320 amps and 
voltage read 10.8 (still in the green scale)
stopped test at 15 seconds and two minutes later battery was back up to 12.7

next step will be check alternator output at battery and terminal point

ok... started truck... engine at 1200 rpm
meter on alternator o/p- voltage is 14.6
meter on battery voltage is 13.5

hmmm...1.1 volt drop in 4' of 1/0 cable....that don't sound right
need to measure resistance of cable I guess...

as an aside... checked voltaged between frame ground and the case of the 
alternator... 0.0001 volts

I also took battery back to Wal mart and Quintella checked it...  battery is 
good based on her years of
battery experience

----- Original Message -----
From: john niolon <jniolon at att.net>
To: shop-talk <shop-talk at autox.team.net>
Sent: 8/6/2021 8:58:12 AM
Subject: [Shop-talk] electrical problem with truck

jeff….     regular led acid battery ??     Everstart Maxx27 800 CCA  regular 
Walmart battery

When it died, did any of the electrical items still work?  Lights, etc.?  when 
it first occurred ,, when I tried to restart, .. starter just clicked and I 
remember the a/c fan still blowing

Donald...  How large is the cable from the alternator to the battery?   feed 
from battery to alternator is #4 wire

Dave... I was thinking a dirty battery clamp.    battery clamps are new this 
year and clean, no corrosion on connections

John...   How is the volt meter in your truck grounded, to the frame or to the 
motor?    voltmeter in dash is grounded to dash frame  voltmeter used to check 
under hood is grounded to frame not engine.  
I'll go back and check ground connections. Alternator has a ground terminal of it's 
own... 
it's #10 wire grounded to the frame and of course the alternator is grounded through it's 
mount.

Pat...  what is the relationship between the frame terminal & the rest of the 
electrical system?  Terminal on the frame rail is fed by a 
4' piece of  #4 wire from the i/p solenoid lug where the cable from the battery is connected to the solenoid.

Jimmie..    What's 
the voltage at the terminal with those accessories 'on' but the engine 'off'    
hmmm ?? don't remember checking that, …  I'll do that

 How big is the alternator?    100 amp single wire from CVF racing

ya'll have given me lots to check and recheck and some I haven't thought of...  
 going back through my diagnostics and check connections too.  I bought a 500 
amp load tester yesterday and will put sufficient load on the battery.  Battery 
is under the cab and I have to lower it to check it out and with the low truck, 
I have to raise truck on jackstands.. silly me, I thought battery would be a 
low maintenance item ...duh.   so checking at a shop somewhere is a very large 
pain.

points I'm considering.... larger ground wires from frame to engine.... alternator to frame and check resistance from solenoid lug to the terminal on the frame...   the saga continues

thanks for all the replies and points to check..   you guys are the best

john

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