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puplot · 09-08-2017, 05:17 PM

I just bought a 93 Winnebago elante a couple weeks ago. I am parked in an rv park and hooked up to shore power. Over the last few days i noticed the automotive battery has been dying. When it does the power step and radio stop working. After reading my manual. I am under the impression that the step is powered by the house battery. The radio is as well when i select aux power For the radio power switch. However even in this mode it is loosing power along with the automotive battery. My question is, could i have a switch or setting wrong or should i be looking for a misswire in the system. Thanks

BFlinn181 · 09-08-2017, 05:58 PM

I'd first unplug from shore power. Then take volt readings of all batteries. Then start the engine. After about 5 minutes of idling, take volt readings again. Then shut off engine, connect shore cord, repeat volt readings again. You now will know if your house and chassis systems connect when a charging voltage (+13.2v) is present. If not, either the battery isolator relay is not working or you don't have one. A battery isolator solenoid connects both battery groups together for charging. When charging stops, the two groups are again isolated from each other.

Do you have a 'boost' switch on the dashboard to connect both groups together to start the engine? If you do, you most likely have a BIS.

vsheetz · 09-08-2017, 06:19 PM

To check if charging is occurring, use a voltmeter on the batteries without charging active. Then activate charging - you should see about 1 volt increase. No change = no charging.

puplot · 09-08-2017, 06:44 PM

I checked the house batteries, and they are charging and holding just fine. My battery switch has a dual / momentary (boost) switch. I use the momentary to jump the battery, and start the engine. The manual says that the dual is used to charge the house batteries from the alternator while driving, but makes no mention of going the other way, (charging the auto batery off the house charger).

puplot · 09-08-2017, 07:05 PM

Battery switches

BFlinn181 · 09-08-2017, 07:16 PM

Quote:

Originally Posted by puplot

I checked the house batteries, and they are charging and holding just fine. My battery switch has a dual / momentary (boost) switch. I use the momentary to jump the battery, and start the engine. The manual says that the dual is used to charge the house batteries from the alternator while driving, but makes no mention of going the other way, (charging the auto batery off the house charger).

Check to see if there's a voltage increase when the converter/charger is plugged in and the switch is turned to 'dual.' The only caution, if you don't remember to switch it the other way when parked with no shore power, you'll have all batteries go dead.

puplot · 09-08-2017, 07:29 PM

No change in voltage

BurienTimmer · 09-09-2017, 01:45 AM

The house charger typically does not charge the vehicle battery. The vehicle battery is charged by your alternator when the engine is running. If there are coach accessories wired to your vehicle battery, in my opinion that is incorrect. Most mh's have a relay or isolator that allows the vehicle alternator to charge both batteries when the engine is running and then when the engine is stopped there is no draw on the vehicle battery (except for parasitic draw fir radio settings, etc.).

Winemaker2 · 09-09-2017, 06:47 AM

If flooded lead acid FLA check cells w a hygrometer...you may have a bad cell.
Parasitic draw is present but should be minimal.
Other option is to have the batty load tested at a shop that sells battys...most auto parts...W World...etc

BFlinn181 · 09-09-2017, 09:36 AM

Quote:

Originally Posted by BurienTimmer

The house charger typically does not charge the vehicle battery. The vehicle battery is charged by your alternator when the engine is running. If there are coach accessories wired to your vehicle battery, in my opinion that is incorrect. Most mh's have a relay or isolator that allows the vehicle alternator to charge both batteries when the engine is running and then when the engine is stopped there is no draw on the vehicle battery (except for parasitic draw fir radio settings, etc.).

In most newer RVs with a battery isolator solenoid, it DOES work in both directions. They connect when a charging voltage is detected, whether from alternator or converter/charger on shore power or generator. In older RVs they were only found in higher end units. They aren't that expensive and I wouldn't have an RV without one because it keeps batteries charged under most conditions without owner intervention.

twinboat · 09-09-2017, 09:49 AM

In your vintage MH the engine charging source may be directed to a diode isolator that splits the charging to both battery banks.

Diode isolators are not bi-directional, meaning the house charging system will not charge the chassis battery.

If that's the case, you can install a tric-L- charge device to handle that.

Some boost solenoids are not built to be on full time. Switching on the boost solenoid, full time, could burn it out.

Google " Battery Isolator " to see what they look like and see if you have one. It's a finned box with 3 medium size cables going to it.

Winemaker2 · 09-09-2017, 10:15 AM

Diode based isolators are older technology and impose a V drop of nearly 1V which means batty will not be fully charged.
Consistent under charging not the best practice for longevity and you are not getting the most of the batty capacity.
Look at batty combiners for a better alternative.
A search for Battery Isolator vs Combiner will provide lots more detail.

twinboat · 09-09-2017, 10:58 AM

Quote:

Originally Posted by Winemaker2

Diode based isolators are older technology and impose a V drop of nearly 1V which means batty will not be fully charged.
Consistent under charging not the best practice for longevity and you are not getting the most of the batty capacity.
Look at batty combiners for a better alternative.
A search for Battery Isolator vs Combiner will provide lots more detail.

What you said is correct, except the MH builders work around the voltage drop by running a sense wire from the alternators regulator, directly to the chassis battery.

With that, the alternator compensates for the voltage drop by outputting the difference. So you do get the correct voltage to both banks but the house will charge at the rate of the charged chassis battery.

Google " Duvac alternators ".

Dutch Star Don · 09-09-2017, 12:39 PM

Many coaches don't charge the starting batteries when connected to shore power. Often this isn't a problem if your RV doesn't use a lot of starter battery power when parked. If your coach does, there are several products (all do the same thing, but various price range) that will charge your starter battery when connected to shore power. They are very easy to install. Usually three wires, one to ground, one to house batteries and one to starting batteries.

This can also be done by simply connecting the two battery banks together with a single wire (positive to positive) , but is not really a safe method. Some do this and then remove the wire when they break camp, again, not recommended.