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Old 20-08-2017, 11:47   #1
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High voltage, Alternator

I've tried two alternators ,both internally regulated. Both have been checked in the shop and are to spec. My voltage keeps climbing to over 14v. The current side seems ok as the amps start at about 40 and drop pretty quickly. The batteries have all been load tested and are fine. I've been told a poor ground can cause this. Can you electrical gurus confirm this? Or do I have other issues .
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Old 20-08-2017, 11:54   #2
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Re: High voltage, Alternator

Over 14v is normal.
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Old 20-08-2017, 11:58   #3
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Re: High voltage, Alternator

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Originally Posted by Cheechako View Post
Over 14v is normal.
Correct.
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Old 20-08-2017, 12:02   #4
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Re: High voltage, Alternator

I thought it should be about13.8
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Old 20-08-2017, 12:06   #5
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Re: High voltage, Alternator

Look at the charging specs published by the mfg of your battery bank.

LiFePO4 and Gel are lower than FLA and AGM.

Ideal is an external regulator that lets you set custom setpoints, like Balmar MC-614.

But yes 14-14.4V is normal and healthy for most flooded and AGM.
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Old 20-08-2017, 12:07   #6
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Re: High voltage, Alternator

The voltage just keeps going up. I know with an external smart regulator the v goes to 14.4 on FLA and then drops but I thought with the internally regulated alternators it only should go to 13.8v.
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Old 20-08-2017, 12:08   #7
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Re: High voltage, Alternator

The voltage went to 14.4 so I stopped the engine.
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Old 20-08-2017, 12:16   #8
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Re: High voltage, Alternator

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The voltage just keeps going up. I know with an external smart regulator the v goes to 14.4 on FLA and then drops but I thought with the internally regulated alternators it only should go to 13.8v.
Rick, 13.8V will take forever to charge. "Normal" charging voltages range from the 14.2V to even as high as 14.6V recommended by Trojan for some of its batteries. This is for wet cells, gels are lower.

The Ample Power Primer http://www.amplepower.com/primer/primer.pdf

I suggest you go to Balmar | Marine Charging Systems | Battery Monitors | Multi-Stage Voltage Regulators | High Power Alternators | Serpentine Pulley Conversions and download ANY of their alternator regulator manuals, in PDF form (so I can't give you a direct link), the latest MC-614 would be a good example. Balmar's manuals have very good tables of charging voltages for different battery chemistries.

They also include very good "How charging works" sections.

That single download would answer tons of your questions.

Good luck.
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Old 20-08-2017, 12:23   #9
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Re: High voltage, Alternator

Quote:
Originally Posted by Vasco View Post
The voltage went to 14.4 so I stopped the engine.
No need

Quote:
Originally Posted by Vasco View Post
The voltage just keeps going up.
unless you saw it go past 14.6, 15, 15.5, then yes get it checked.

What is the max Absorb voltage recommended by the mfg of your bank?


Quote:
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I know with an external smart regulator the v goes to 14.4 on FLA and then drops but I thought with the internally regulated alternators it only should go to 13.8v.
No, all charge sources on a given bank should have a similar profile.

Smarter regulation gives more adjustability, customization of the profile, not a different range completely.
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Old 20-08-2017, 13:11   #10
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Re: High voltage, Alternator

Over 14 volts for shorter periods of time will cause no harm.
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Old 20-08-2017, 13:32   #11
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Re: High voltage, Alternator

My solar panels at high noon push my batteries to about 14.5, which is higher than the cut-in on the engine internally regulated unit. Sometimes when I start the engine I get no tach, but pegged over oil or temp until I " blip " the throttle to stabilize the harness. then everything goes to normal. May factor into your concern.
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Old 20-08-2017, 14:45   #12
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Re: High voltage, Alternator

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Over 14 volts for shorter periods of time will cause no harm.
For as long as it takes to get to full, will cause no harm, even over 12 hours.

Very few chemistries do you ever want **less** than 14V as long as it is actually charging.

After full, on Float voltage, yes, 13.4 to maybe 13.8V, again depends on the bank.

See mfg specs for that model batt.
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Old 20-08-2017, 15:03   #13
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Re: High voltage, Alternator

I am motoring along as I type this showing 14.3 volts. Batteries need water only once per year.

All good

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Old 20-08-2017, 15:18   #14
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Re: High voltage, Alternator

Yeah, 14.2-14.6 is pretty normal. If you are worried you can also check battery temps or look out for gassing if they are wet cells.

I did once have a battery sense wire with high resistance cause the regulator to overcharge to 15.5v. That was a big issue.
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Old 21-08-2017, 15:11   #15
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Re: High voltage, Alternator

What alternator? I went through this with a Korean brand. The shop which sold it 'checked it out as ok, but the truth was
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