Battery idiot light and high charge voltage - Ford Powerstroke Diesel Forum
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post #1 of 5 Old 07-20-2019, 03:39 AM Thread Starter Rookie
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Battery idiot light and high charge voltage

OK, I have a 2005 E350 Superduty Van with a 6.0. Single alternator.

Few days ago in hot weather, a battery shaped idiot light in the dash lit and the scan gauge showed charging almost a volt higher than normal. Now the charge fluctuates from 13.5-14.4v, (it normally fluctuates between 12.4-13.3). When it was cool the next morning I started the van and same thing, battery light and high charge voltage. The alternator was replaced last summer, and has been fine, till this.
Any one experience anything like this before? Any suggestions?
Thanks in advance for the valuable advice always provided on these forums.
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post #2 of 5 Old 07-20-2019, 04:00 AM
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I'm going to head straight for the alternators voltage regulators got a little problem. But I also would be sure to clean all your battery cable connections and apply some grease on terminals too.

Take alt back and install a new one.

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post #3 of 5 Old 07-20-2019, 04:11 AM Fanatic
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The place you bought the alt from should also be able to test it once you get it off.

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post #4 of 5 Old 07-20-2019, 01:30 PM
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Before you get rid of your alternator, what type of batteries do you have? Odyssey (AGM)? From what I understand reading the “Odyssey Technical Manual” a charging voltage of 14.4V-14.7V is optimal and a maintenance trickle charge voltage of 13.5V-13.8V is recommenced for maximum battery life. My Voltage on my scan gauge 2 varies from a low of 13.9 to a high of 14.7. That is not including before, during or after starting. I have never seen a battery idiot light indicator on my dash.

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Last edited by BTL; 07-20-2019 at 01:56 PM.
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post #5 of 5 Old 07-20-2019, 01:54 PM
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The typical regulator at battery will start off with a goal of 14.4, but has a thermistor in the regulator to bring that down to 13.6 to 13.8 to prevent damage to the standard batteries at high underhood temps. It hasn’t been until recently that Ford is adopting AGM and altering the regulator for that battery style.

While the cluster battery light is normally on for a low voltage alternator output, it will also come on if a diode in the alternator is bad and outputs a wider range of A/C current. Meters Switched on DC are dampened enough to not show that, but switching over to A/C can. Some have seen a voltage on OBD2 monitors over 15 with a bad diode.

This guys not too bad.

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