Coach power problem

[Mike Collins]

Went to start the motorhome several days ago on a relatively cold morning using the dash switch to hook the two battery banks together. Cranked for about 5 seconds, no start. The control panel for the inverter went through a diagnostic and finished with one red blinking alarm. Everything else on inverter panel was dark. The CMP 20 rebooted, went through diagnostic, all green except DC battery light was red, with battery showing 9 volts.

We had no coach power at this time. Went to re-hook up shore power so that we could use the engine preheat. No power to the shore power cable reel motor. Used an extension cord to hook up shore power. As soon as ac power restored, all was well with the inverter panel and the CMP 20. DC battery showed 13.7 volts.  Ran the diesel burner and engine preheat for 30 minutes, and the Cat engine fired up after 1 second of cranking (not using the dash switch to hook the two battery banks together). We ran the engine preheat for the next 3 mornings and had no problem starting the Cat.

Several times we have since lost coach power, once by turning on one 12 volt light. Never had a problem if the generator was running, plugged into shore power, or with the Cat running.
 
Any suggestions as to what our problem is?

Mike Collins

[Steve Huber Co-Admin]

Mike,
Could be a number of things but I would start by having all your house batteries checked. I wouldn't be surprised if you find one or more that are bad.
Steve

[Joel Ashley]

Like Steve, I'd start with the battery banks - connection integrity, corrosion, chassis ground connection, and internal battery condition.  Since you say all is well apparently at the supply post (where I've oft discovered bad outlets), and things work when external power is supplied, I'd consider that perhaps the Echo charger or charger within your inverter, whichever your rig uses, might be out, although I'm not sure you'd be seeing the 13.7v if it was.  At 9v. though, the charge rate should be high and the panel should read at first well over 14 volts.

Joel

[Keith Moffett]

We had a similar problem.  The alt. Was good and the inverter was good when we left the rv park.  We drove all day thinking the batteries were charged.  Battery connections were also clean and tight.  We got to a dry camp and put the slides out and had dead batteries.  Even the chassis batteries were being drained.  We barely got the generator started.
We made it to a shop the next day and found out the battery temp sensor was shot.  The multi meeter read 12.4 volts but when we unplugged the phone connector for the  temp sensor the batteries jumped up to 13.2.
30 bucks for the temp sensor and we are good.

Keith

[Bill Sprague]

Mike,

We never had a problem like that with our Beaver.  But, a few weeks ago I was having fits with the new "motorcabin".  It had been delivered with a couple Interstates for house batteries.  Karl Welhart used a voltmeter and saw that house battery voltage dropped quickly as soon as the charge source was turned off.  He explained it should be steady.  Karl suggested that this indicated a bad cell.

There was an Interstate Battery Store near where we were in Utah (on the way to Branson).  Their tech stuck a hydrometer in each cell of both batteries and declared a dead cell in each.  The dealer we bought the "motorcabin" from bought us two new batteries and all the headaches disappeared. 

Get a hydrometer and check all the cells or call Karl and he can explain how to use a voltmeter to do it.

[Keith Moffett]

Good info. Bill
Were these 6V or 12V Interstates? 
I had intended to replace our House batteries this spring so now it will be a higher priority.

[Bill Sprague]

Good info. Bill
Were these 6V or 12V Interstates? 
I had intended to replace our House batteries this spring so now it will be a higher priority.

The motorcabin came with a pair of 12 volt "deep cycle"s.  6 volts are too tall for the small space provided in the motorcabin.   It is so small, that servicing them was a literal pain in the back.  To even see in a cell required battery removal.  To solve it I bought a cleaver thing called a "Flow-Rite MP2000 Qwik-Fill 2 Battery Kit".  You attach a squeeze bulb with a hose in a bottle of distilled water, squeeze a couple times and all the batteries are topped off.   I could have solved it with AGMs but those are too pricey for me. 

If your question about 12 or 6 volt has to do with the voltage measuring technique or hydrometer use, it doesn't matter.  A dead cell is a dead cell.  One dead cell means you have to replace that battery.  If you replace one battery in a set, the common recommendation is to replace all in the set.   By being careful to keep them clean,, serviced and never deeply discharged, I got away with replacing batteries a single time in the Beaver.  The Trojan T-105s were 8 or 9 years old and showed no sign of weakness when I sold it.   If it was not plugged in, I ran the Onan a lot!  Quartzsite style camping meant a minimum of 2 hours at wake up and 2 hours before going to bed at night.

[Keith Moffett]

The reason for the questio had more to do with the Interstate brand.  12V Interstate I am told is Johnson Controls as are many others but the 6V Interstate is made in Mexico.
I have been trying to learn more about quality of batteries and how much success folks have had or continue to have like the Trojans.  They were the best but when corporations changed values many of the key employees went to US Batteries which are now better and cheaper. Or so I am told.

[Bill Sprague]

The reason for the questio had more to do with the Interstate brand.  12V Interstate I am told is Johnson Controls as are many others but the 6V Interstate is made in Mexico.
I have been trying to learn more about quality of batteries and how much success folks have had or continue to have like the Trojans.  They were the best but when corporations changed values many of the key employees went to US Batteries which are now better and cheaper. Or so I am told.

It is a dilemma.  Wet cell batteries are a simple commodity of lead and sulfuric acid in a plastic case.   I'm not sure a consumer can tell what he or she is getting.  Interstates are at least a brand with a written warranty.