Conservation of energy

[Keith Moffett]

We started out today after a full night of 50 amp shore power.  We drove about 60 miles with the inverter on.  The water heater was on as was the icemaker though that was full so just keeping cold.  The refer was on gas but could have switched to electric with the inverter coming on.
When we arrived, the aqua hot would not fire and the generator would turn over slowly but not start. 
I tested the batteries.  The Magnum equalizer disconnect light was on instead of the green light and the house batteries said about 7V over two batteries.  The chassis batteries said 13V.  By combining batteries I got the gen. started and am now getting about 14.5V to all batteries and the aqua hot started up fine, smoky but fine.
Question is, what did I do wrong?  The house batteries are just now 4 years old and the connections fairly clean. 
The alternator runs at 14.4V though I admit to not watching it closely the last two days.

Did we over use the inverter?

Thanks
Keith

[Mike Groves]

From my experience the answer is no.  We've run all of that while travelling.  Of course I've already mentioned that our alternative is losing 1V and I only read 12.8 to 13.2 while running down the road.

There have been times when I allow the fridge to run on AC also assuming its already cold when we started out.  Not sure about the ice maker but the fridge and instant hot would cycle on and off and haven't created an issue for us.  Lately though we've always had the fridge on gas (when not using the generator) since we're only going weekends or short trips after the coach has been sitting, and since our customary trip is from Portland to Newport, we just turn on the generator to exercise it for the 2-3 hour trip down there.

Sounds like the charging issue is coming from the alternator to the whichamacallit that controls the charging of the chassis/coach banks from the alternator.  Maybe there is a fuse inline to the coach batteries that went out. But you didn't do anything wrong as far as energy management.

Mike

[Steve Huber Co-Admin]

Keith,
The Uline Ice maker will draw up to 20A so we shut ours  unless we are on generator or shore power. We fill a container with ice and put it in the reefer freezer. The Uline is insulated well enough that you  get minimal melting when off.  Not clear to me which water heater you are referring to. The coach water heater and reefer are not wired to run off the inverter alone so they should not be adding to the battery load (unless your coach is wired differently.
Steve

[Keith Moffett]

Thanks Mike and Steve
Something ran  down the house batteries but also ran down the chassis batteries pretty good.  Tomorrow I will start it up and check the alternator.
The alternator charges the chassis batteries but will kick over to house batteries when chassis are full right?

[Edward Buker]

Steve,

The alternator can reliably put out about 100amps continuously, it is rated at 165 amps but it is self monitoring and will limit its own output as it heats up. So if your inverter has a 10 amp AC load you will consume about 110 amps DC given inverter efficiency is less than 100%. That means that there is little current left to run the coach and recharge the batteries.

If this continues and you know that the AC loads have been minor then check that the heat sink on the backside of the alternator is clean, that the fan belt tension is correct and not slipping, the batteries do not have a shorted cell, both the battery banks see 13.8V on the posts at start up with the alternator charging with the batteries charged from an overnight stay. While driving you should continue to see 13V plus on the Silverleaf/Alladin.

If your batteries and charging system check out OK then the only explanation is what you suspected, that you had too high of an AC load which is usually heating elements like mini water heater or motors like the compressor in the icemaker. I would have both those items off while traveling with the inverter on.  Any electronic type loads are light.

Later Ed

[Dick Simonis]

Kieth., it sounds like one problem may have been the Magnum echo charger.  The red light probably indicates that you may have blown the fuse so there was no charging current to the house batteries.  A few hours of heavy load may have depleted the house batteries.  On mine, the water heater isn't on the inverter circuit but the ice maker, insta-hot and all the AV stuff is constantly on.

I've seen my coach pulling over 100 amps of DC when I lost shore power but I've never checked the battery voltage after a trip before hooking up shore power.

Once the echo charger is back up and running you may be just fine but something to keep an eye on.

[Jerry Carr]

Keith, be sure to run the APU before you pull out or for an hour while driving to get the load off the Alternator  you don't want to burn up the Alternator.

I have also run with the APU running for 5-6 hours when we lost the alternator it's not a problem doing this and you may want to try it to keep your batteries charged.

I would also check the fuses  to the echo charger to see if this is a problem.       

[Al Lewis]

As hard as I try I have never got more than four years out of house batteries. If I have the coach stored and forget to turn the inverter off the batteries will be down in a day or two. This is true even if I turn the switch to disable house dc. Batteries being completely discharged for several days will severely degrade good batteries. When my inverter is on and all a.c. loads are off it still draws six amps dc. I have determined that this is all standby power of tv's and electronics.  Satellite receivers are probably the biggest power hog even turned off.

[Keith Moffett]

A few questions
1) Jerry - What the heck is an APU?  Do I have one and is it curable?
2) should the generator be chargong all the batteries at once?  Chassis and house are getting 14.6V with it running.
3) CMP says I am drawing 70 - 90 amps off the generator.  Isnt that high?
4) After running the gen. For a couple hours last night the batteries read about 13.8V.  They were still hot so may have setteled some but 3hours later they read 12.9V and at bedtime 12.6V.  We used the water pump just a little and no lights or AV at all.  Flashlights only.   No power at all.  Upon rising the batteries were 12.8 chassis and 12.6 house.  We barely got the gen running all batteries combined.
The echo charger comes on green as soon as the generater runs.   Is there perhaps a drain through the BIRD system?

Thanks 
Keith

[David T. Richelderfer]

1.  A= additional or alternative or anal... or something.  So an APU is some sort of "power unit."  Most of us call it simply a generator.  That's my guess...

2.  If you have a BIRD system like I do, then there have been numerous threads/messages here on the Forum explaining how they work.  Since it has been awhile, I will guess that the generator first charges your coach batteries, then once those are charged, the BIRD system allows charging of the chassis batteries.  Doesn't it work just the opposite from the alternator?  I don't know...

3.  I have not a guess.

4.  My coach is a power hog.  If it's not plugged in or with generator running, then the coach batteries will deplete very quickly.  Many times I will get parked and before I can get the slides out and leveled, it's generator has auto-started.  The slides and hydraulic jacks seem to draw a lot of power.  I suppose that is also with a few other things drawing power, like TVs, DISH receivers, insta-hot, fridge w/ice maker, computers, cell phones charging, etc., plus the regular stuff that always draws power like the engine and transmission computers, etc.

I purchased a Northern Power 3000w portable generator that I keep in the pickup.  It has a 75' remote start so I can start and stop it from anywhere inside the coach.  Most of the time now if we don't have shore power, then I go start the portable generator before I put out the slides and level.  It's just a routine I have grown accustomed to - power first, then slides out and level.

[Edward Buker]

Keith,

If you have an Echo Charger you do not have a Bird unit. Both of these combine the battery banks for charging purposes when the house batteries are being charged but the Echo Charger is current limiting to about 15amps so it will charge the chassis bank slower, more for maintenance of charge scenario. When you stop charging the batteries will slowly drop in voltage until they actually reach the voltage level of the charged state, maybe 30 minutes after you stop charging. The voltage level of 12.6V and 12.8V after overnight are levels that indicate that the batteries still have plenty of charge which you would expect from your limited use of current that you described. See this chart...

http://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/

I think you may have some poor contacts in the cable lugs, lead oxide or corrosion at the battery post, or a ground cable to chassis corrosion/rust issue causing voltage drop while starting the coach or generator. There are some exposed bolts on the right side of the generator, if yours is like mine, where you could measure with a voltmeter prior to cranking and while cranking to see if the generator is getting at least 10.5V while cranking. There are cases where the batteries can be charged but due to sulfation just have very limited active plate area to provide current.(batteries act like much smaller lower capacity batteries) If your batteries are old or have been deeply depleted a lot that could be contributing to your starting issue. Seems like one or the other of these issues has to be involved if your voltages are as high as they are.

Later Ed

[Jerry Carr]

Sorry Keith old habits are hard to break Gen Set =APU Auxiliary Power Unit a small jet engine or fuel driven generator that will supply ground power while on the ground.
 

 

[Keith Moffett]

Sorry Keith old habits are hard to break Gen Set =APU Auxiliary Power Unit a small jet engine or fuel driven generator that will supply ground power while on the ground.

Had that figured but a little humor at times like these is a good thing!  Thanks for the chuckles!

[Keith Moffett]

Thanks everyone for the input.
We were attempting our first drycamp in this MH.  We were out on the coast of Wa. Where anything electrical decides to go bad for us.  The last coach did this too so its a tradition.
Back at the shop a quick look over showed the battery temp sensor was bad.  We had driven two hours and the alternator was putting out 14.4 V.  Half hour after arriving the chassis batteries said 13.2V even with shore power and with turning lights on all batteries read 12.9 and dropping.  When the temp sensor was unplugged the meter jumped up to 13.2.
This still doesnt explain why the house and chassis batteries seem to be locked together.  They charge and test the same.
Ed!!
I clean the connections 2-3 times a year but they do have a little blue on them.  Looking at the other connections is sure a good Idea!  Must be part of the issue because no way will the generator or engine start when batteries read under 12.9 but at 13.2 the gen set fires right off!
Keith

[Keith Moffett]

David
Sounds like what I find to be wrong here may help you in the long run.  I will update here as we find more though I know new cables and perhaps batteries are in the works just to narrow the possibilities.  I have parked this MH on its home pad but not plugged it in for several days.  The batteries were still over 13V.
More in the next couple days.
Keith