Chassis battery charging

[LEAH DRAPER]

Gerald
As always thank you for your response.
When I am plugged into shore power my house batteries stay charged, therefore I am assuming that the charge part is working fine, but  the inverter part is off, if I am understanding what I think I know!  
But the chassis batteries have NEVER stayed charged.  I have added a small charger just attached to the chassis batteries so that when I am connect to shore power they  are trickle charged.  I did that because they kept going dead.  Either I have not understood things well ( very possible) or the
Big Boy isn't working.  
I have an appointment at BCS in Bend Sept 10 and it is on my list you better believe.  I want to get to the "bottom" of this once and for all.

I hope some day I have the opportunity to meet you as you always seem to look out for me.  I'll give you a big HUG (assuming it's ok with your wife of course).

Thanks again
Leah

[Bill Sprague]

Well Bill
If I am plugged into shore power, I don't need it and if the generator is running, I don't need it.  
Therefore, most of the time it is off.  Don't see any need to have it on so just haven't.  When I need it I do turn it on.  Hope that answers your  question.
Leah

Leah,

That makes sense.  

I leave mine on.  Four primary lights, the ice maker, my Verizon MyFi, two computer chargers and two phone chargers all circuits that come through the inverter.   If I leave it on, it is one less thing I have to remember to turn on on driving days when I want those things to work.  

The other reason I leave it on is for winter storage.  If the 30amp power source goes out in a storm the dehumidifier that I leave plugged in will draw down the batteries in about 30 minutes.  That will trigger the genset to start.  In turn, the genset will provide power to the hydrohot to keep it from freezing.  

My inverter  has not been off for 8+ years!  Perhaps its a bad habit!

Bill

[Keith Oliver]

Bill:
Every inverter I have seen draws power if turned on, and does so even when no loads are drawing from the inverter.  Some may be more efficient than others, but the ones I have measured (not on my Beaver yet) draw lots of power unloaded.  My Xantres MS2000 on my boat for example, draws ~8 amps before any loads are added.  Leave that on overnight and the battery voltage drops so far that one needs to run the genset for a while.  Use AC accessories as well and more generator time is required.  Forget it for a day or two and you get dead batteries.
That is why I keep my inverter set to off most of the time.
Not an issue if you are always either plugged in or running the engine.

[Bill Sprague]

Keith,

I look for opportunities to run the generator, so I don't mind the inverter draw.

We were dry camping for several days last week.  Our Xantrex controller has a gauge.  If I go to bed with it at 100% full, leave the inverter on and run ceiling fan all night, it will be at about 90% in the morning.  My batteries are 5 years old.  The controller's "Fuel Gauge Cutout" is set so that 11.4 volts, under load,  is assumed to be dead.  I program the generator to autostart at 60%, if I forget so start it myself.    So, in reality I think I've never had the house batteries below about a 30% discharge.  

When our motorhome was new I got to go to some factory sponsored rallies where Onan and others put on seminars.  A key message from Onan was that we are using a commercial duty genset that is built to run often and hard.  The leading cause of failure and repair in motorhomes comes from lack of frequent use.   As hard as I try to use it frequently, I only have about 400 hours on ours.

In a forum elsewhere on the net about generators there was a thread about genset failures.  One guy had 20,000 hours of Onan use without repair.  The people that rarely used theirs, had  the most failures.  

Bill

[Jeff Watt]

This is interesting especially when one reads the other current thread about generator failing to start where Gerald posted:

"On the '06 Patriot, Monaco used the house batteries to start the generator.  So if the house batteries are discharged to about 11.5V or less with normal usage, the generator will not start unless you start the engine to charge them back up or hold the boost switch down while starting it.  The solution is to rewire the generator starter to the chassis batteries, or never run the house batteries below 11.9 to 12 volts."

I have been operating somewhat as Bill mentioned:

 " The controller's "Fuel Gauge Cutout" is set so that 11.4 volts, under load,  is assumed to be dead.  I program the generator to autostart at 60%, if I forget so start it myself.    So, in reality I think I've never had the house batteries below about a 30% discharge."  

by assuming that deep-cycle batteries can be taken down to 11.5 or so. I too have my genset set to start at 60%.

I am reading the two statements by Gerald and Bill and I don't think they are contradictory, however will the genset in the 06 not start if it was programmed to do so? Also, Gerald, doesn't the boost switch use the house batteries to assist the chassis batteries?

I gather that in pre-'06 units the genset is started by the chassis batteries?  So if chassis batteries are weak then use the boost to assist starting of the engine and I assume the genset?  But in '06+ units if the house batteries are weak, then the genset can't start unless the coach engine is started to charge them up (which is hard on the alternator), assuming the engine starts.

Maybe I making it more confusing that it really is.

Jeff

[Gerald Farris]

Jeff,
If you are operating your house batteries in the same manner that Bill outlined, your batteries will not be discharged below 11.9V. This will help you receive longer battery life, as well as no problems in starting the generator if it starts with the house batteries instead of the chassis batteries.

You said that you thought that the boost switch used the house batteries to help the chassis batteries. Since the boost switch is used to tie both battery banks together, the starting help can go either direction. If the chassis batteries are discharged and the house batteries are not, the boost switch will assist the chassis batteries, however if the house batteries are discharged and the chassis batteries are not, the boost switch will assist the house batteries.

Gerald

[Jeff Watt]

Thanks Gerald for your insight.

I didn't realize the boost feature worked both ways - good to know.

Jeff

[Robert Mathis]

The "boost" switch is really just a parallel switch that ties both batteries together.