Xantrex wontcharge

[Tom and Pat Fudale]

My Xantrex RS2000 inverter quit charging. Have run through all of the tests with Xantrex tech. I would like to know if I can hook up a charger to my house batteries without disconnecting the inverter. This would be just until the new inverter arrives.

[Edward Buker]

An educated guess would be yes that should be fine as long as the Xantrex did not fail due to a shorted device that is now pulling a lot of current. What would be evident, if that was the case, is that the house batteries would be rapidly discharging and the charger that you connect to your house batteries would not be able to get the bank charged and deliver enough current to do the job.

Hitch up the charger and just monitor how it is doing current output wise and if that current at some point diminishes as the battery bank charges as it normally would. Hope this helps.

Later Ed

[Tom and Pat Fudale]

Thanks ED, Hooked up the charger and the gauge on the charger is slowly going and battery volt is slowly going up.

[Bill Sprague]

I was parked in a friends driveway for a few days where the best I could get was a 15 amp outlet in the garage with a 50 foot cord.  Plugging the motorhome into the small cord and setting the Xantrex control panel to 10 amps would have worked until one of us tried to turn something on.  Genset use would have been too rude in that neighborhood.  

Instead I hooked up an automatic Sears battery charger to the house batteries and "dry camped".  Everything worked except air-conditioning and HydroHot electric heat.  The battery gauge on the Xantrex control panel would drop during evening hours with the lights on, TV on and HydroHot running.  By morning the gauge would read almost full.  My charger label says it draws up to about 8 amps so my friends cord and outlet were not challenged.  

It seemed to me that where you are severely limited in amps, or are in a place where the campground power is not trusted, that putting a relatively cheap charger between your motorhome and the power grid might be the best way to plug in.  I asked a few people (including one Monaco engineer) and posted the question on line.  The answer was always "It does not seem to be a good idea, but I can't tell you why."  

Yet it seems to me that the motorhome electrical system would see the batteries with a charger on them at about 13 volts the same as with the alternator providing about 13 volts.  

[Tom and Pat Fudale]

It seems like this 12 volt, 10 amp charger can only bring the batteries up to 12 volts. am I correct?

[Bill Sprague]

Not exactly.

If you charge a new battery, disconnect everything from it and  let it rest an hour it should read 12.66 on a voltmeter.  Run something with that same battery for a while and let it rest.  At 12.45 it is 25% discharged.  At  12.25 it is half gone.  Not until 11.9 is it considered dead.

The trouble with using volts to measure your battery is that any load at all changes everything.  Our cars and motorhomes always have a small load on them from the refrigerator, smoke alarm, inverter, engine, transmission, radio, clock and other things that are always hooked up.  Everything has a circuit board.

I parked my car a couple of hours ago and just checked the battery.  Out of curiosity I checked and the volmeter said 12.5.  Then I hooked up a charger and it went up to 13.9.

The way I understand it is that you must feed a battery about 14 volts to charge it and it will never get above 12.6.  While you have it hooked up to your motorhome it can be fully charged but a voltmeter will read around 12 volts because of the constant parasitic load.  

So it might be that after you have run the charger for long enough to fully charge your batteries a voltmeter might read 12.0.  Or, depending on the load, it might read 11.9 or 12.2.

The real mystery comes when you program automatic generator start that most of us have.  The idea is to have the generator respond when the batteries are "low" but not so low that you have shortened the service life.  On mine there are two steps.  First you program the gauge and then you program the point on the gauge you want the generator to start.  Because of the always present load, my gauge is set conservatively to have a reading of 11.5 as "empty".  Then when the gauge gets to 40%, the genset starts.  It is only an estimate because of the ever present load, but I'm guessing I operate off the top third of the battery capacity which ensures long life.