Charging Batteries

[MrJackSprat]

Quick question that may be an easy answer. Does engine alternator also charge coach battery when traveling? On the flip side does shore power/gen also keep engine battery charged when parked?

[Wertles]

Running the motor does charge the coach batteries however, running the generator or being plugged in does not charge the chassis batteries. At least this is true for a 2012 Greyhawk but seems to be pretty standard across class C’s.

[pconroy]

Originally Posted by Wertles

Running the motor does charge the coach batteries however, running the generator or being plugged in does not charge the chassis batteries. At least this is true for a 2012 Greyhawk but seems to be pretty standard across class C’s.

also true for my 2016 Greyhawk.

found this out when I went out to our Plugged In RV and the chassis battery was dead.

Dead Coach battery - start the Ford engine and it'll recharge.
Dead Chassis battery - push the emergency start button to start the engine

[Robbbyr]

There are devices that can be installed to rectify that situation, allowing the converter to also charge the chassis battery or batteries. I am lucky, my Seneca does charge my chassis batteries when I have 110-volts available.

One aftermarket example: https://www.rvupgradestore.com/Ultra...-p/tls-oem.htm

[Mark S]

Originally Posted by Robbbyr

There are devices that can be installed to rectify that situation, allowing the converter to also charge the chassis battery or batteries. I am lucky, my Seneca does charge my chassis batteries when I have 110-volts available.

One aftermarket example: https://www.rvupgradestore.com/Ultra...-p/tls-oem.htm

How do you know that you are charging the chassis battery on 110? Is there a way for me to verify if mine is doing the same?

Thanks

[Robbbyr]

Originally Posted by Mark S

How do you know that you are charging the chassis battery on 110? Is there a way for me to verify if mine is doing the same?

Thanks

You can put a voltmeter on the chassis batteries, but in our Senecas they are not that easy to access. You may not see an immediate increase in voltage when you hook up to AC power, but over time the voltage should be maintained. The device that is installed in mine to provide this functionality is described here: http://www.precisioncircuitsinc.com/...nager-RevF.pdf

I can easily see both my coach and chassis battery's voltage in my Onan Energy Command 30 control panel by cycling through its readings, but my understanding is they don't use the same generator control panel on newer Senecas.

A work-around might be a cigarette lighter plug-in voltmeter like below, plugged into a cab dash outlet: https://www.amazon.com/Battery-Elect.../dp/B00AQAQIGO

[RVermont]

Would the scan gauge show this if the key is in the auxiliary position? I have a scan gauge but really haven't done much with it. I know it show voltage when the engine is on....


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[Cunning193]

Every one seems to agree on the fact that the alternator charges the coach battery. How does the alternator do this and how do you troubleshoot the circuit when it fails?

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[tom35758]

Don't know if my Granite Ridge is special or what..... But have the coach power hooked up to 110 whenever we are not travelling(more often than I like)
The coach and E450 batteries are always at 12.9V, which definitely tells me it charges both 12V systems

[Mark S]

Originally Posted by RVermont

Would the scan gauge show this if the key is in the auxiliary position? I have a scan gauge but really haven't done much with it. I know it show voltage when the engine is on....


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I am plugged in to 50 amps and just checked my ScanGauge with the engine off. The voltage on the Scan Gauge reads 12.7 volts. The inverter panel is showing 13.5 volts.

This indicates to me that the house batteries are being charged while the chassis batteries are not.

[pconroy]

Originally Posted by Cunning193

Every one seems to agree on the fact that the alternator charges the coach battery. How does the alternator do this and how do you troubleshoot the circuit when it fails?

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Not sure how much detail you want on the how. I certainly can't give much. But the coach and chassis electric are obviously connected -- pressing the "Emergency Start" button started my engine using Coach Battery power.

Why it's one-way these days, who know. Maybe Ford laid down the law and worried about interconnecting the systems.

[ALJO]

The chassis batteries never get charged by the converter.

[JFlightRisk]

The systems are probably much different today, than when we had an '85 class A on a Chevy P30 chassis, but our MH had two batteries under the hood. Both batteries charged when the engine was running. The chassis battery was connected to an isolator that prevented the coach from draining it. It also had the "emergency " rocker switch for times there was a no-start situation.

[Cunning193]

Converter charges fine as well as the generator, but the alternator does not. Not sure if it's supposed to. If jayco included an isolator I can not locate it.

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[Robbbyr]

Just got back to our unit in Maine after storing it here for 2 weeks while we were back home. Plugged back in at campsite and it is showing 13.3 volts on both my chassis and coach batteries on my Onan panel where I can scroll between them. Obviously mine does charge both as it was supposed to on a 2014.

Perhaps a call to Jayco is in order to find out if your unit is supposed to charge them like older ones do. If not, maybe ask why not too!

[Cunning193]

I had them send the schematics. I did not see anythin going to the alternator. I'll have to post them and see what the group thinks.

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[ALJO]

Why should a manufacturer of MH RV's want to change something what is already in place. The alternator always charges the chassis battery and the converter charges the house batteries (on shore power). What their add on can be is the alternator through an isolator to charge the house batteries while the engine is running. This last modification anyone can do if he's capable of. The logic is to keep the two battery systems isolated. It is the same for Trucks and pull type trailers. When MH's have a generator on board the logic is to charge the house batteries not the chassis battery.

[Robbbyr]

Originally Posted by ALJO

Why should a manufacturer of MH RV's want to change something what is already in place. The alternator always charges the chassis battery and the converter charges the house batteries (on shore power). What their add on can be is the alternator through an isolator to charge the house batteries while the engine is running. This last modification anyone can do if he's capable of. The logic is to keep the two battery systems isolated. It is the same for Trucks and pull type trailers. When MH's have a generator on board the logic is to charge the house batteries not the chassis battery.

One issue that my stock Seneca electrical system addresses is the fact that any MH chassis battery or batteries will have parasitic drains and self-discharge as any lead/acid battery will over time. Set up at a campsite for several weeks (or longer) and you may find that the starting batteries won't start it! Yes, I can hit my Emergency Start switch and draw off the house batteries to get it going but excessive discharges kill any battery's life expectancy. Likewise, if you have been dry camping somewhere and your house batteries are somewhat depleted, having them charged by the MH's alternator as you drive to the next adventure is sure handy.

I agree the two systems need to be isolated, and they basically are in my unit. Discharging one set (house or chassis) will not deplete the opposite set. The place the two banks of batteries interface is the Battery Isolation Manager in my Seneca. When on shore power it keeps both banks of my batteries fully charged via the converter/battery charger. And when driving, the Freightliner alternator does the same. My opinion - the best of both world without thinking about it or adding anything else to the system.

Now if the newer Senecas or other Jayco motorhomes don't have that capability anymore, I have to wonder "why not"?

[ALJO]

If the chassis battery get drained by the house electrical system then the electrical design is wrong. Unless your chassis battery has to much parasitic drain. It would be the same leaving your TT plugged in to a TV without isolator (or solenoid with switch).
Jayco can change the design anytime they like if it is customer friendly or not. Hope their electrical designers can think through their schematics and see if things will work. If this was my unit I would want the chassis battery isolated totally from the house batteries. Ram has always power on the 12+ connector (I changed it to solenoid and switch) so if leaving plugged in during an overnight stay and heavy use of house power it could drain the chassis battery enough to not able to start the engine. When travelling the chassis battery gets topped and also the house batteries, why on earth would Jayco their electrical design want to drain the chassis battery? In my opinion that is totally wrong. Even if their is an emergency switch to fall back on the house batteries. What if they are drained..........that leaves you stuck in the middle of Nowhere.

[Robbbyr]

Originally Posted by ALJO

If the chassis battery get drained by the house electrical system then the electrical design is wrong. Unless your chassis battery has to much parasitic drain. It would be the same leaving your TT plugged in to a TV without isolator (or solenoid with switch).
Jayco can change the design anytime they like if it is customer friendly or not. Hope their electrical designers can think through their schematics and see if things will work. If this was my unit I would want the chassis battery isolated totally from the house batteries. Ram has always power on the 12+ connector (I changed it to solenoid and switch) so if leaving plugged in during an overnight stay and heavy use of house power it could drain the chassis battery enough to not able to start the engine. When travelling the chassis battery gets topped and also the house batteries, why on earth would Jayco their electrical design want to drain the chassis battery? In my opinion that is totally wrong. Even if their is an emergency switch to fall back on the house batteries. What if they are drained..........that leaves you stuck in the middle of Nowhere.

I think you misunderstood me. My chassis batteries (I have two Group 31 units in parallel) cannot be drained by my house loads. If I completely discharged my house batteries, I still would be able to start the Cummins provided things are "normal".

But there are parasitic drains in my chassis system unrelated to any coach loads, just as there are in all newer cars and trucks today. A Freightliner M2 chassis has a complex multiplexed electrical system and power is "on" to many of its modules all the time. Plus certain electrical devices work off of the chassis batteries, not the coach batteries. My power steps are one example. I can have the coach batteries disconnected and the power steps still work. Freightliner doesn't recommend regularly disconnecting the chassis batteries as a matter of routine. Many cars and trucks today have to "re-learn" certain operating parameters if the batteries are disconnected from the system for a time.

If I did something forgetful like leave the truck headlights on and completely drain my chassis batteries, it will not deplete the coach (house) batteries. They are isolated from each other EXCEPT WHEN CHARGING. Or when I hit my "Emergency Start" switch which ties the house batteries in momentarily to get the Cummins started.

Charging either set of batteries off of either 110-volts (from the converter) or the alternator (when driving) requires no intervention on my part, and it is the way Jayco built my unit utilizing the Battery Isolation Manager installed in my unit. I just keep my flooded lead/acid house batteries topped off and don't have to worry about it. I load test my chassis batteries once a year and when they show deterioration I will replace them to keep everything reliable.

I hope that makes better sense, I am protected from unexpected "no starts" so long as everything works as it should.