Voltalogical Oddities: Normal or WTF?
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Joined: Jul 2009
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From: North Carolina
Voltalogical Oddities: Normal or WTF?
To ignore or not to ignore, that is the question. Because when my battery dies, it's ALWAYS when I have a horse in the trailer and a ride time to meet. Hence, I am proactive.
Starting battery is about 6 mos old, other battery is maybe 1.5 years. Both are good batteries from AutoZone with the most CCA I could get.
This morning, I get in truck and turn key to cold start it. It makes a weak cranking attempt, pulling dash battery meter down to almost 8, and dies. I try a second time and it starts after maybe 5 wheezes, but shows 11 V. As I put it in gear and drive off, voltage jumps immediately back to about 14 (I have a ScanGaugeII).
Putting voltmeter on both batteries shows about 12.5 V. Yet when I turn the key to put on glow plugs, SG still shows 11 V. Went and had both load-tested at AutoZone, machine said they were fine. Nothing was left on overnight.
ETA -- Yes, it's been cold (for us) overnight here for about a week but that has had no effect prior)
Starting battery is about 6 mos old, other battery is maybe 1.5 years. Both are good batteries from AutoZone with the most CCA I could get.
This morning, I get in truck and turn key to cold start it. It makes a weak cranking attempt, pulling dash battery meter down to almost 8, and dies. I try a second time and it starts after maybe 5 wheezes, but shows 11 V. As I put it in gear and drive off, voltage jumps immediately back to about 14 (I have a ScanGaugeII).
Putting voltmeter on both batteries shows about 12.5 V. Yet when I turn the key to put on glow plugs, SG still shows 11 V. Went and had both load-tested at AutoZone, machine said they were fine. Nothing was left on overnight.
ETA -- Yes, it's been cold (for us) overnight here for about a week but that has had no effect prior)
Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Check your cable connections and grounds to make sure nothing is loose. Having the batteries draw down to 11v or so when you first start isn't unheard of. Let it idle for a couple of minutes and see if the voltage goes back up to 14 when the glow plugs cycle off.
Keep an eye on the voltage while driving and make sure the alternator isn't starting to act up. I finally gave up on autozoo junk alternators when they quit replacing my batteries for free. Watch to make sure voltage isn't getting too low or too high occasionally while you're driving around.
Keep an eye on the voltage while driving and make sure the alternator isn't starting to act up. I finally gave up on autozoo junk alternators when they quit replacing my batteries for free. Watch to make sure voltage isn't getting too low or too high occasionally while you're driving around.
Logistics Pro
Joined: Jun 2005
Posts: 4,243
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From: AZ
Also, if you find a battery bad, replace them as sets (I noticed that you didn't the last time). Hooking one new battery to one old battery equals two old batteries quickly. Both your batteries are tied together parallel (pos to pos, neg to neg), they are both starting batteries.
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From: North Carolina
The alternator is original as far as I know, it appears to be doing well. Good point about batteries of different age, I had not considered that they were wired together. Self --> 
I am definitely keeping voltage on the gauge for a while so I can watch it. *sigh* Thank you -- I hope they will not do what I fear they will do. Batteries are expensive - although I suppose if they die, they'll have to give me two new ones at once.
I hate learning from experience!
I am definitely keeping voltage on the gauge for a while so I can watch it. *sigh* Thank you -- I hope they will not do what I fear they will do. Batteries are expensive - although I suppose if they die, they'll have to give me two new ones at once.
I hate learning from experience!
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