What is normal alternator voltage

terra26 · 11-04-2010, 03:56 PM

I have a 2005 P series and the voltage has been 14.1 volts for years. The other day the alternator failed and was replaced. Now my voltage is 14.6 - 14.7. is this too high.

tncruiser · 11-04-2010, 03:58 PM

that should be in the acceptable range
brianj

dieselclacker · 11-04-2010, 04:14 PM

14.7 is a little too high for my tastes. 13.8 to 14.2 measured at the battery terminals is ideal. Higher than that particularly on a long trip can cause some water useage and excessive off gassing atthe battery. Not much you can do about it. The built in voltage regulator is replaceable, and there is a lower charge rate regulator available for genuine alternators. Do a search here, I recall someone on this forum did the research and came up with the lower voltage regulator and part number.

Dieselclacker

Clay L · 11-05-2010, 07:07 AM

Mine jumps from 14.2 to 14.8 volts and all points in between. I called Workhorse and they said that was normal. The average is probably about 14.4 volts or so.

hamguy · 11-05-2010, 07:30 AM

Quote:

Originally Posted by terra26

I have a 2005 P series and the voltage has been 14.1 volts for years. The other day the alternator failed and was replaced. Now my voltage is 14.6 - 14.7. is this too high.

Last year I finally got tired of replacing batteries after 2 years of service. My alternator was regulated to 15.0 +/-. I had talked to a number of X-spirts who all said that was high but ok. I took the rig (2002 WH) to a local alternator shop and he said it was too high. He then pointed out that the regulator came in 2 sizes. 15.2 and 14.4. The difference being the 15.2 was made for solid state isolator and the 14.4 was for relay type isolators. He ordered and installed a 14.4 and my problems disappeared.

BTW, the regulators are adjustable.

DriVer · 11-05-2010, 08:01 AM

Quote:

Originally Posted by Clay L

Mine jumps from 14.2 to 14.8 volts and all points in between. I called Workhorse and they said that was normal. The average is probably about 14.4 volts or so.

That's what I have and I expect it to stay in that range. Typically will see ~14.4 volts.

Mahlon · 11-05-2010, 11:54 AM

Quote:

Originally Posted by hamguy

<snip>I took the rig (2002 WH) to a local alternator shop and he said it was too high. He then pointed out that the regulator came in 2 sizes. 15.2 and 14.4. The difference being the 15.2 was made for solid state isolator and the 14.4 was for relay type isolators. He ordered and installed a 14.4 and my problems disappeared.

Correct, the alternator is actually made with a variety of different regulators, all intended for different applications. Some voltages are appropriate for starting batteries only; 14.4V constant voltage is correct for deep-cycle batteries through the relay isolators (winds up being something like 14.1 or 14.2 back at the batteries after all the voltage drops) but that's still a bit high, but then again that's not a long-term condition. The long-term condition is when the batteries are being charged by the AC charger; there, more sophisticated charging schemes take over.

Quote:

Originally Posted by hamguy

BTW, the regulators are adjustable.

Eh? How do you do that?

UFO Pilot · 11-05-2010, 01:03 PM

Why does the Solar Expert cited on this site say to charge the batteries to 14.8 volts?

rogueii · 11-05-2010, 01:26 PM

Mine is fairly constant, @ ~14.3 volts.

terra26 · 11-05-2010, 04:11 PM

I found a web site selling the 14.2 volt reg. for the DR244 alternator.Do a google search for SPRING HILL AUTO ELECT part # d202xhd. Around $30 and I think I will try one.

Mahlon · 11-05-2010, 07:42 PM

Quote:

Originally Posted by wthomas1

Why does the Solar Expert cited on this site say to charge the batteries to 14.8 volts?

There's more to the story: charge the batteries to 14.8 volts, then drop the voltage down to the float charge value (something like 13.8 volts) which is what a multi-stage charger would do. For a constant voltage charger (which is what an engine-driven alternator is) you have to choose a compromise between charged capacity and water loss; that compromise is somewhere around 14.2 volts.

Mahlon · 11-05-2010, 07:44 PM

Quote:

Originally Posted by terra26

I found a web site selling the 14.2 volt reg. for the DR244 alternator.Do a google search for SPRING HILL AUTO ELECT part # d202xhd. Around $30 and I think I will try one.

You'll need an external Torx bit to get the alternator apart, also.

DriVer · 11-05-2010, 09:24 PM

We were having a discussion about AC voltage and amps. Has anyone considered that when an alternator makes more volts, for instance in a 120V circuit when you see something like 124V, that works really great. Why is that? Because a load that consumes watts and doesn't care where it gets its power from whether its volts or amps. If you provide more volts you need to produce fewer amps. Therefore when you have a 140 amp alternator you can run a lot of stuff and still have a lot of reserve capacity. 14.4 VDC is looking better all the time and I would prefer it over 13.8 if that's all it was cranking out.