The refrigerator on my Class C MH (2020 Coachmen Freelander on Chevy 4500 chassis) runs on 12V DC only. Recently, the refrigerator controller started to put out error code indicating “the operating voltage out of range”. Since this specific error/problem happens only during driving, I was then able to correlate it to the chassis alternator; When the engine is running the alternator would also charge the house battery, from which the house refrigerator draws its power. So, when the engine is running, I measured the voltage at the house battery terminals to be 15.4V, which I was able to confirm to be the cause for the refrigerator “operating voltage out of range” and the consequent power cut-off error. The operating range is 10.4 – 14.2V.So, the question is: is the behavior of this alternator normal – operating in a typical range? Or is it showing signs of going defect? Not very knowledgeable about Alternators, somehow I feel it is not right. I could leave the alternator alone since I haven’t noticed anything else being wrong about the vehicle (yet), in the meantime, just to power down the refrigerator during the vehicle is moving and to turn it back on after set up camp to circumvent the problem. However it is not a solution really. Thanks in advance for any insight or suggestion.

Just a guess, but have the coach battery tested. It may have a problem, and the alternator is trying to compensate with outputting at a higher rate of charge.

I would check the Voltage regulator. Might be internal, not sure.thread on alternators

bobndot wrote:I would check the Voltage regulator. Might be internal, not sure.Exactly my thought.

Does the 2020 Chevy chassis have a warranty? I would take it in and have it checked. Yes 15+ volts is the high side of normal possibly indicating an issue to resolve.

The max voltage should be 14.7~14.8.15.4 is WAY beyond normal (and it has nothing to do with the battery). You are well into the danger zone and will be boiling your battery and frying electronics.

Is it normal for an Alternator to generate 15 V+ output?

Chum_lee
Explorer
Feb 07, 2022
Your vehicle should be under factory warranty. The more you (or others) fool around with it, the more reason(s) the factory has to blame you for the issue and deny warranty repair(s). IMO, ASAP, take your RV to an authorized factory repair facility and explain the issue just as you have done here. Do not try to repair what you do not understand. If you are having this issue with a relatively new production vehicle, most likely, others are too. Use the collective knowledge base of the entire industry (rather than ignoring it) to help solve your problem.

Chum lee
bobndot
Explorer II
Feb 05, 2022
Yes, new car warranty will cover the alternator.
MDKMDK
Explorer
Feb 05, 2022
fwiw, I had a 2002 Roadtrek upfitted into a 3500 Chevy Express Van. I got around 180,000 miles out of the original alternator before it finally gave up, and one of the symptoms was a battery indicator light on the dash. I spent about 1/2 hour in a rest area on I-90 in Montana checking the chassis battery connections and everything else I could test, until I finally decided it wasn't the battery, and took it to a GMC shop in Billings where they replaced the alternator. No problems after that, batteries and alternator lasted another 30,000 miles until I sold the van.
Good luck with it.
specware2020
Explorer
Feb 04, 2022
Thank you all for sharing your knowledge and providing suggestions.

Acting upon all your input, I went out to do more thorough measurements and tests. Regardless of whether the house battery is connected or not, 15v+ always presents at the chassis battery. To answer one of the follow-up questions, the MH does not have a solar charging system, and the built-in house converter/charger works properly as its charging voltages are below 14v pretty much all the time whether the AC source is shore power or the generator.

I don’t know how long I have been driving it under this condition – the batteries being "cooked" by the alternator… five to six hundred miles maybe? Not sure how much damages have already been done to them although I haven’t seen any noticeable symptom yet. Come to think of it, that the dash console infotainment center is acting strange lately may have something to do with it.

Packing with the knowledge you all provided and the data collected, I will bring my vehicle to the Chevrolet dealer for them to take a look at the alternator. The vehicle is under warranty and I hope they will get my problem fixed without much hassle as it sounds like what would be entailed is a straight alternator replacement…, or no?
BurbMan
Explorer II
Feb 04, 2022
Matt_Colie wrote:
At 15.4, it is outgassing like it left a Mexican restaurant....

Too bad there is no "like" button on these posts, that was awesome!
Matt_Colie
Explorer II
Feb 04, 2022
Spec,

Yes, that is way high for an alternator output. If you are seeing 15.4 at the battery, it is not going to be useful for very much longer either. At 15.4, it is outgassing like it left a Mexican restaurant and when the electrolyte (water/acid) in it gets low, the plates will start to flake and that will be all she wrote....

Matt
CA_Traveler
Explorer III
Feb 04, 2022
Check both battery banks at the posts (not the cables) with alternate only, shore power only and solar only if available and post. Have all batteries load tested and alternator tested which is usually free. I'd also make sure all battery connections are bright and clean. Note that the cable to lug connection can be corroded especially near flooded batteries.
Diamond_c
Nomad
Feb 04, 2022
Go to auto zone ,orielys, or the like and ask them to test your alternator. Hey will do it for free. I’m not a mechanic but I’d say that it’s bad. If he coach has a warranty then take it to the dealership.
bobndot
Explorer II
Feb 04, 2022
Specware2020 wrote:
Since this specific error/problem happens only during driving, I was then able to correlate it to the chassis alternator;

If … ‘Only during driving’ wouldn’t it be voltage from alt/reg. ?

As said a 2020 should be under warranty if not over the mileage cap.
BurbMan
Explorer II
Feb 04, 2022
No, that voltage is way high, you have a problem somewhere. On a GM chassis the voltage regulator is internal to the alternator, so it gets replaced not repaired.

Usually there is a circuit breaker in the charging circuit to the house batteries to prevent high current but not high voltage. usually if there is a problem with the battery you will see high current not high voltage.

I would measure voltage at the coach battery with the engine running and see if you get the same 15.4v, if so them my money's on a bad alternator. If you get a more normal 13.6 at the coach battery, then the alternator is OK and the problem is somewhere on the house side, potentially a bad battery.

Are there other charging sources like solar connected to the house battery? If so that charge controller may be causing the problem by not dialing back the power when the alternator comes online.

I would also house measure battery voltage when connected to shore power, it's possible the charging circuit in the converter is bad but that's unlikely.