Community Forums

Ddonyes · 11-18-2021, 08:09 PM

I have a Class A Coachman Aurora 35 ft motorhome. Recently we are experiencing issues with the coach batteries servicing the RV. We usually boondock with no electrical support.
We can drive for several hours and the panel inside will show low levels. The solar panel will show charging but inside panel still says low. When running the generator we don’t get full battery power on the panel either. We had the batteries checked and they said they were good, no need to replace at this time.
Please give me some ideas.
Thanks Dixie

RV Driver · 11-18-2021, 08:13 PM

What do you mean by “…the panel…”?

Ddonyes · 11-18-2021, 09:04 PM

Quote:

Originally Posted by RV Driver

What do you mean by “…the panel…”?

The panel inside the rv that give you battery, water, tank levels. And the panel appears to be accurate as we run out of battery quickly and the lights are dim.

OldWEB · 11-18-2021, 10:37 PM

I installed one of these connected to the house batteries.

I use one of these in the dash lighter socket which monitors the chassis battery when the disconnect is closed.

Both are within 0.1V accurate with my meter.

You need to know what the values are, not just four "idiot" lights... You can also ensure all battery connections are cleaned to ensure they take a charge.

HarryStone · 11-18-2021, 10:50 PM

Sounds like the alternator isn’t charging the coach battery. You should have the solenoid checked that allows that.

Ddonyes · 11-19-2021, 03:59 PM

Quote:

Originally Posted by HarryStone

Sounds like the alternator isn’t charging the coach battery. You should have the solenoid checked that allows that.

I’m confused, it sounds like your talking about the chassis battery that starts the engine of the motorhome? I’m needing help with the coach batteries that provide power to the living quarters. Thanks for your help.

Jthigh · 11-19-2021, 04:33 PM

Quote:

Originally Posted by Ddonyes

I’m confused, it sounds like your talking about the chassis battery that starts the engine of the motorhome? I’m needing help with the coach batteries that provide power to the living quarters. Thanks for your help.

The alternator also charges the house batteries once the chassis batteries are charged. Once the chassis batteries reach a predetermined charge voltage a voltage monitor circuit cuts in a relay to charge the house batteries while driving.

Could be low alternator output or the relay circuit that engages to charge the house batteries may not be working.

wolfe10 · 11-19-2021, 04:38 PM

Correct-- the alternator should charge BOTH battery banks.

And, if you want help, please post exact voltages using a digital voltmeter (start under $25) for:

Chassis and house battery banks with no shore power and engine OFF.

Chassis and house battery banks while on shore power OR generator on.

Chassis and house battery banks with engine on and over 1,000 RPM.

This will eliminate the GUESSING/SPECULATING.

MN_Traveler · 11-19-2021, 04:53 PM

The alternator really does not supply much power compared to genny or being plugged in. Driving “several hours” starting with depleted batteries will not charge them fully. You need to think in terms of running the genny 6 hours or more to charge the batteries.

I know you had the batteries checked… but your symptoms just sound like batteries at end of life. If you are not consistently fully charging them every day, that EOL will come quickly

CharlesinGA · 11-19-2021, 09:26 PM

Quote:

Originally Posted by MN_Traveler

The alternator really does not supply much power compared to genny or being plugged in. Driving “several hours” starting with depleted batteries will not charge them fully. You need to think in terms of running the genny 6 hours or more to charge the batteries.

I know you had the batteries checked… but your symptoms just sound like batteries at end of life. If you are not consistently fully charging them every day, that EOL will come quickly

You have this backwards, the generator or the shore power will only provide the charge to the battery bank that the converter puts out, usually 45 to 70 amps. Not too many converters larger than that. Modern alternators can put out a 100 amps or more to the coach batteries.

The thing to do is (disconnect solar if you can) take a good voltmeter and check the voltage of the chassis and coach batteries with no shore power, no generator and engine off. Then with the engine running, measure the voltage of the chassis (engine) battery, then measure the voltage of the house (coach) batteries. Do this with no shore power and no generator. Your alternator will be charging the chassis battery with over 14 volts, the coach batteries should be VERY close to this. If you do not see a rise in voltage at the house batteries with the engine running, then whatever device is used to connect the two systems with the engine running is failed. Some use a BIRD system, others use a simple relay/solenoid activated by the ignition.

Being a Coachman (and a Ford F53 chassis?), I'm willing to bet its a simple relay, and the contacts have burned up. RV manufacturers tend to cheap out and not use good relays in these systems.

Charles

Ddonyes · 11-20-2021, 09:27 AM

We just had to replace the windshield wiper relay because the manufacture used to big of fuse. Where would this charging relay be located?

wolfe10 · 11-20-2021, 09:33 AM

Quote:

Originally Posted by Ddonyes

We just had to replace the windshield wiper relay because the manufacture used to big of fuse. Where would this charging relay be located?

Sorry, please explain.

A fuse (or even just a straight wire with no fuse) will not cause damage to anything it is running.

What does the "windshield wiper relay" have to do with a "Charging relay".

Again, details please.

Persistent · 11-20-2021, 03:01 PM

“Class A Coachman Aurora 35 ft motor-home. Recently we are experiencing issues with the coach batteries servicing the RV. We usually boondock with no electrical support.
We can drive for several hours and the panel inside will show low levels. The solar panel will show charging but inside panel still says low. When running the generator we don’t get full battery power on the panel either. We had the batteries checked and they said they were good, no need to replace at this time.

The panel inside the rv that give you battery, water, tank levels. And the panel appears to be accurate as we run out of battery quickly and the lights are dim.”

Good advice above, but motor coaches are complicated machines. They are configured in many different ways. Controls and settings can be confusing. Malfunctions in these systems become major mysteries.

I include a link below that spells out the basic concepts of house or coach 12 volt systems.

Facts:
Coach or House batteries were tested and found OK.
Solar charging works. Built in charger using generator or shore power does not seem to work.

System design:
Generator provides 120 volts AC to built-in converter/charger or inverter/converter/charger.
Charger provides 12 volts to battery.

Failure points can be:

120 volt circuit breaker to charger. Turn breaker fully “off”, then back “on”
12 volt fuse or circuit breaker in 12 volt wire. It may be on a fuse panel with other fuses or alone in the electric bay.
Loose or corroded wires. Look for burned insulation or corrosion around connectors. Tighten screw connectors. Wiggle wires to look for weak points.
Defective charger. A converter charger runs 12 volt lights. Start the generator and disconnect the battery. If lights stay “on” generator and converter are working. If lights go “off”, either generator output is not working or converter output is not working.
Battery disconnect relay. Many motor coaches have a 12 volt house disconnect switch near the entry door. This switch operates a relay in the electric bay that connects or disconnects much of the 12 volt system. The relay sometime develop a fault and leaves the converter charger disconnected from the battery.

Solar may bypass all of the above possible points of failure.

12 volt Side of Life part 1
The 12volt Side of Life (Part 1)