Charging Chassis Batteries

[Bruce Sevier]

Currently it appears that the chassis batteries are not being charged when plugged in to shore power.  This is a 1999 Marquis.  Has been plugged in for over 24 hours and voltage at batteries is 12.55 V when it used to be around 13 v when plugged in.

Prior to this it sat for about 2 weeks with inverter off and the power switches on. Then turned the switches off and it sat for another week.  I then turned the power back on and tried to start the engine.  The starter solenoid engaged but the motor did not turn over.  I tried again using the battery booster switch and still no success.  Plugged it into shore power for 24 hours and tried again.  Turned the key on and to start and no lights on the dash and no headlights.  Checked voltage at chassis batteries 1.9V.  Used a portable battery charger overnight and with batteries at 12.6 V the engine started and everything worked.

I am concerned that something has failed to allow the coach batteries to be charged while plugged into shore power. I wonder if using the battery boost switch has something to do with this.  Batteries are 3 yrs old and have been trouble free since new.

Any help in solving this would be greatly appreciated.

Thanks

Bruce Sevier

[David T. Richelderfer]

When plugged in or running the generator, the house batteries ARE being charged but it appears the chassis batteries are NOT being charged?  If the house batteries ARE being charged by the inverter/charger, then 1> the inverter/charger is likely working properly but 2> the battery combiner (BIRD/Big Boy, ECHO, etc.) may not be passing the charging voltage through to the chassis batteries.

12.55v on a stand-alone 12v battery is nearly fully charged...   12.65v to 12.7v is fully charged.  When the inverter/charger is charging the batteries, then you should be seeing the higher charging voltage coming from the inverter/charger (not the batteries' voltage) that is 13.3v or higher.  When the batteries become fully charged, then the charging voltage will settle down to 13.4v to 13.7v and maintain that 13v+ level.

On the other hand, if your coach engine is running and the alternator is charging batteries, then you should be seeing a charging voltage of about 14.1v+.  Again, you would be seeing the alternator's charging voltage, not the batteries' voltage.

If your answer to my first question above is YES, then I am guessing your battery combiner (BIRD/Big Boy, ECHO, etc.) is the first place to look.

[Fred Brooks]

   Bruce,
I am not sure but I believe your coach has an "echo charger". It is a device that trickle charges the chassis battery. It is located on the left bulkhead of the battery compartment. It has 2 yellow glass fuse holders. One goes to the isolator chassis terminal and the other goes to the house battery terminal of the isolator. Another way to identify is the solid red wire is the house batteries and the red wire with the yellow tracer line is the chassis battery. It is common to have the fuse fail on the house battery wire. The way it works is as follows: When the Echo charger senses more than 13 volts coming from the house batteries, it starts to charge the chassis batteries. When the coach is plugged into shore power, the inverter/charger will charge the house batteries and eventually trigger the echo charger. To check the glass fuses inside the yellow fuse holders, you just pull them apart. I think they are "SFE-20" fuses. Fred

[Bruce Sevier]

Thanks David and Fred for your help.

The chassis batteries are charged by the alternator when the engine is running. They are not being charged when plugged in.

It does have a Echo Charger with the yellow fuse holders as you described Fred. In my rush to check the fuses one end of the fuse broke off in the holder. Sadly I failed to check the light on the Echo Charger first. So tomorrow I plan to correct my error and check for a light in the charger.

If the light on the charger does not come on, where do I check next? Or is it common for the Echo Charger to fail and should I just buy a new one?

Bruce

[Fred Brooks]

    Bruce,
    The most common failure of the Echo charger is the fuse. If the coach sits for a long time, the parasitic amperage draw will eventually drain the chassis battery. When the coach is plugged into shore power, the house batteries start to charge and eventually reach the 13volt threshold that activates the Echo charger. Sometimes the dead chassis batteries will blow the 20amp fuse. Before you repair the broken fuse, charge the chassis batteries first. If they won't take a charge, replace them. Please read the Echo charger manual. Go to "Coach assist" then scroll down to "Battery charging systems" then click on "Echo charger" The earlier system may not have the Green LED to indicate it is working, only a red LED if there is a failure. Merry Christmas and Blessings to you! Fred

[David T. Richelderfer]

And DO NOT run the coach engine to charge both the chassis and coach battery banks from a discharged condition.  If necessary, attach two battery chargers, one to each battery bank, with both chargers plugged into shore power until the batteries are mostly charged up.  Running the coach engine to charge up well-discharged batteries is hard on the alternator and may overheat its components and cause a diode to burn out.  Then, guess what, you will be replacing the alternator...  been there, done that!

[Bruce Sevier]

Thanks again to both of you. Mine has the green light. I'll be trying to get the broken fuse out today. Will let you know my results.

I did charge the dead chassis batteries with a separate charger before starting the engine.

Merry Christmas and Happy New Year to you and your's.

Bruce

[Bill Borden]

David,

The example you give with discharged Chassis batteries is right on.

A few years ago, I picked up our Coach at an indoor storage facility, we keep her indoors during the winter.

This time the electrical connection was not available, so to counter the discharge gremlins I have installed Battery Disconnects switches on both the House and Chassis battery banks.  My guess is they forgot to turn off the batteries.

It started Ok, with no hiccups.  They had pulled it out before we arrived, so I wasn't aware of a low battery condition.

Well by the time I arrived home the batteries were dead and so was the Alternator.

I have an Alternator, Generator, and Starter repair company nearby that I have used before.

The only problem was a bad diode.  The repair cost, $50.00.

So a hard lesson was learned.  Hopefully, my money won't run out before I receive my full education.

[Bruce Sevier]

Thanks Fred and David for your help and insight. After making a connection to the broken fuse on the red w yellow stripe wire the green LED light on the Echo Charger was not on.

The Heart Interface echo-charger is no longer available so I bought a Xantrex Digital echo-charger 82-0123-01 from Amazon. It's the same size and shape of the old unit and comes with all wiring and fuse holders like the original unit. The only difference is the fuse holders are inverted so you can't connect to the old fuse holder connected to the battery cables. Also besides unplugging from AC power and turning off the power switches I disconnected the battery cables.
Once the new echo-charger was installed I turned on the master switches and plugged into AC power. The green LED light came on as soon as I reconnected the battery cables.

As the house and chassis batteries were being charged voltage to the house batteries was slightly over 14V and the chassis batteries slowly climbed to 14V. Once all the batteries were charged as shown on the inverter panel in the coach. The voltage at house batteries is high 13V and the chassis batteries are lower 13V. 

Once again this forum has helped me learn about, solve and repair a problem without great expense.

Happy New Year

Bruce

[Fred Brooks]

    Bruce,
 I am glad you experienced the JOY. It sure is fun when you solve a problem. From your description of the operation, it is working as engineered. Incidentally, Xantrex bought Heart interface about 20 years ago and the replacement Echo charger is a dependable replacement. Happy New Year! Fred