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Author Topic: intermittent converter problems  (Read 462 times)

Chet

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intermittent converter problems
« on: June 23, 2018, 10:17:52 AM »
Good morning,
I have an electrical gremlin in my 2008 Winnebago 26p class A motor home.  It has the workhorse 8.1L motor and chassis. The problem has come about several times while camping. I'll be on shore power, and sometimes it appears the batteries are dead.  The lights dim, sometimes the gas detector alarm goes red and beeps, and the levels indicator shows no charge in the batteries. Then after awhile, everything is back to normal... I've considered an accidental switching off of the battery disconnect, but whether on or off this makes no difference.  I'm presuming there is some problem with the inverter/converter?  I don't think it is an inverter -  I think this MH has a converter that converts 110 to 12v, and maybe its not working, (nor is it recharging the batteries) so once the batteries die, I get the dead battery indications.  For example, on the last two night camping trips, on the first night, by bedtime the batteries were dead, the alarm was red and blipping, then by morning all was back to normal, and batteries levels indicated full charge.  On the second trip, first night was fine, then second night the lights dimmed, batteries indicated dead, and this time they did not recover overnight.  Trip was over so I drove an hour home, and batteries were charged, but I presume via the motors alternator.  I've not heard the cooling fan come on since being home, so the converter may now be done.

My mystery is that I can have no problems, sometimes for days while on shore power, (and I never had an issue while full timing as a Florida snowbird this winter) then the batteries go dead.  Then suddenly, the batteries will be fully charged and it's as if there was never a problem.  There is a cooling fan that when running, indicates to me the converter is working or charging.

So... is this as simple as some loose connection, or does it mean I need to replace the converter that may be working intermittently, or is there a relay or some switch that turns on the converter when the batteries reach a point of low charge?  Also, it there any way I can test any of these?  I have a multimeter, but just need more intel on how this thing works and what troubleshooting I could do here at home?

I'm hoping the collective wisdom of this group may have suggestions or experience with this issue.  I'm also hoping it is a resolvable issue for me at home and I can avoid $110/hour labor fees from the  "rv professionals."  TIA for patience with the long post and for any thoughts on my issue. - Clem
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

AStravelers

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Re: intermittent converter problems
« Reply #1 on: June 23, 2018, 10:45:00 AM »
Your RV has a converter, unless someone installed an inverter with a built in charger and disconnected the converter.

Have you checked the water level in the batteries?  The water must be above the plates.  If the plates are exposed your battery(s) are toast.

Any corrosion on the battery cables?   

If the above checks out you need to put your multi meter on the DC and 20V scale and measure the voltage at the batteries.  It should be at about 13.4V when plugged into shore power or generator is running.  Disconnect from shore power and see what the voltage is.  If you have been on shore power for 12 hours or more the battery voltage should be from about 12.8V to 13.4V as soon as you disconnect from shore power.  After a few hours of sitting, with no lights or other things on in the RV the voltage should drop to about 12.6V for good fully charged batteries.   I would hook up the meter and just monitor the battery voltage every 1/2 hour or hour and watch to see what is happening.

Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

Gary RV_Wizard

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Re: intermittent converter problems
« Reply #2 on: June 23, 2018, 11:01:11 AM »
You should never have a problem when on shore or genset power because the converter/charger should be supplying all 12v needs. The battery is essentially dormant, receiving charging if needed but otherwise not a player.  If becomes an active player if the converter stops converting, but only then.

So, it could be an intermittently failing converter, but it could also be intermittent shore power. If the 120v power to the converter  goes away, the converter no longer converts and the battery takes over. And eventually goes dead after using its stored power.

One possibility is that the converter/charger is overheating and shuts down for awhile.  Blocked air flow, for example.  Another is a look connection, either the incoming 120v to the converter or the output 12v wiring.  A third is simply an intermittent internal failure in the converter - not likely but possible.
« Last Edit: June 23, 2018, 11:11:31 AM by Gary RV_Wizard »
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darsben

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Re: intermittent converter problems
« Reply #3 on: June 23, 2018, 11:13:23 AM »
I had the same problem and it was a bad battery disconnect in the ground line.
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John Canfield

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Re: intermittent converter problems
« Reply #4 on: June 23, 2018, 04:31:01 PM »
How old are your house batteries?
--John
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Chet

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Re: intermittent converter problems
« Reply #5 on: June 23, 2018, 10:09:06 PM »
Thanks for the replies and the information on how this system works!  The house batteries are just a year old.  I will check the fluid in the cells tho, and put the meter on the batteries as has been suggested.  I don't think it's failing shore power as it has happened at several different places, and once I plugged into the neighbors shore power yet the problem remained.  I haven't checked the connections but will tomorrow. The disconnect ground line issue is also something I'll check. That makes sense as when it returns to normal the batteries are charged.  Finally, I'll check for the blocked air flow too.  stay tuned! - C
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

Gary RV_Wizard

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Re: intermittent converter problems
« Reply #6 on: June 24, 2018, 10:08:33 AM »
Don't rule out shore power because of that.  Your shore power can fail due to a faulty shore cord,  flaky auto transfer switch, or bad wire connections at the load center (breaker box). Could be as simple as a loose wire on the branch circuit that feeds power to the converter/charger.

Next time the problem occurs, immediately check around to see what still has 120v power, e.g. outlets, appliances, etc. If the fridge has shifted over to LP gas instead of electric, that's a sure sign of at least partial 120v (shore) power loss.  You might plug a lamp into a wall outlet and leave it on 24/7 as a quick way to detect general loss of 120v power, but the problem could still be on the converter 120v power circuit only.
Gary
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Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Chet

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Re: intermittent converter problems
« Reply #7 on: June 25, 2018, 07:46:07 AM »
I checked connections, all are intact, batteries in good shape w no corrosion. How do I find or test the switch that activates the converter? Or, is it possible my power cord is faulty resulting in partial power loss, assuming there is such a thing?  Would I test that w a multimeter at an outlet? Thanks for your ideas, electric issues confound me!
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

AStravelers

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Re: intermittent converter problems
« Reply #8 on: June 25, 2018, 10:55:18 AM »
I checked connections, all are intact, batteries in good shape w no corrosion. How do I find or test the switch that activates the converter? Or, is it possible my power cord is faulty resulting in partial power loss, assuming there is such a thing?  Would I test that w a multimeter at an outlet? Thanks for your ideas, electric issues confound me!
Water level in the batteries?

Quote from your original posting:  " For example, on the last two night camping trips, on the first night, by bedtime the batteries were dead, the alarm was red and blipping, then by morning all was back to normal, and batteries levels indicated full charge.  On the second trip, first night was fine, then second night the lights dimmed, batteries indicated dead, and this time they did not recover overnight.  Trip was over so I drove an hour home, and batteries were charged, but I presume via the motors alternator.  I've not heard the cooling fan come on since being home, so the converter may now be done.. "

I really doubt your batteries were dead.  More likely a bad connection somewhere.  Batteries usually don't go from completely dead to full charge in a few hours or a 1 hour drive with charging from the alternator. 

I believe you are depending on the idiot lights to indicate if the battery if full or half full or dead.  These lights are not very accurate.  This is where you need the meter attached to the battery to see the actual voltage. 

Here is a link to good info about batteries and as you scroll down there is a battery voltage to state of charge (SOC) chart.  Note that this chart is for when there is no load on the battery, i.e. all the RV lights turned off, etc.  http://www.marxrv.com/12volt/12volt.htm

If you batteries are truly going dead, you will normally see a slow decrease in voltage from full charge at 12.6V to around 11V.  If the converter is working you will see a pretty constant 13.4V to 13.6V.  If it is a newer 3 stage converter/charger you could see up around 14V for a while.

About the fan in the converter.  It should only run when working pretty hard at charging the batteries or supplying a pretty heavy 12V load.  If it is putting out about 13.4V it is working.

Again you need to volt meter to measure the voltage at the batteries when everything is working and again when the things are not working.  Otherwise we are kind of guessing as to the problem.
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

Gary RV_Wizard

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Re: intermittent converter problems
« Reply #9 on: June 25, 2018, 11:12:15 AM »
There probably is no switch to activate the converter - it is always on and starts working whenever 120vac power is present.

It would help if we knew what brand & model the converter/charger is - most of us aren't familiar with your model of coach.  We are struggling here because there is little info about the actual set-up in your coach - they are not all the same. Also, does the coach have 30A or 50A shore power?  It's possible to have partial power loss with 50A, but not 30A.

If the converter/charger is integrated with the main power panel (120v as well as 12v), it receives its power internally from the 120v side. If it's a separate converter box, it probably plugs to an outlet or is wired to a circuit breaker. In either case, you verify 120v power to it at the source with a voltmeter.   You can verify if the converter/charger is working by checking the DC output voltage to the battery - it should be 13.3-14.3 whenever the converter has power.  If you aren't getting that, start checking for the converter input power as mentioned earlier.

This type of problem requires a careful and rigorous diagnostic procedure.  Measure voltage at various points and report actual results here, so we can share what you are seeing.  Sorry, but "I checked and it's ok" doesn't much help the experts who are trying to apply their experience.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

John Canfield

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Re: intermittent converter problems
« Reply #10 on: June 25, 2018, 12:37:52 PM »
He's 30 amp shore power and a 45 amp converter/charger. Typically the converter/charger is a stand-alone box that can be hidden almost anywhere depending on the particular coach model.

It appears you have an issue somewhere on the 12V side of your house batteries. There should be a house 12V power disconnect solenoid that is operated when you switch on house power. If that's intermittent then symptoms like you describe can happen. Like others have suggested, the converter/charger seems an unlikely candidate for the cause of the problem.

You should have a "Battery Boost" switch somewhere on your dash that bridges the house and chassis batteries together. Next time you have these same symptoms, operate that switch and see if power is restored. Let us know if that solves your problem.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
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Chet

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Re: intermittent converter problems
« Reply #11 on: June 25, 2018, 07:46:27 PM »
John's right, 30 amp shore power, 45 amp integrated converter charger.  Its a Parallax series 7300.  I monitored the voltage at both the house batteries and at what I think is the output from the converter to the batteries for a of couple hours this afternoon.  During this time, the condition I've seen camping occurred and I was able to get readings in that condition as well. 

I hit the battery boost switch, but it resulted in no change.

I don't know how to access the point at which the 120 volt power comes to the converter...

Figures on the voltmeter with three overhead lights on in the coach:

At the batteries         at the converter to the batteries
at 1800 (in mil time)
             11.98v                        11.36v
1830  lights dim, "bad" condition
            11.9v                          7.4v
hit "Aux Batt" switch, (that I was informed is the battery disconnect switch, located near the door) seemed to fix the condition...
readings went to
            11.9v                           11.6v
1900     11.3v                           10.8v
1920      7.5v                              7.9v
1925 converter fan came on
              12.2v                           12.7v
2005 converter fan still on
                12.5                           12.9

Thoughts?

Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

Chet

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Re: intermittent converter problems
« Reply #12 on: June 25, 2018, 08:00:27 PM »
Oh! The first time the power dropped, hitting the "on" battery disconnect fixed the problem. The next time, at 1920, neither the battery disconnect, nor the battery boost on the dash had any effect. Sorry for that confusion.
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

John Hilley

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Re: intermittent converter problems
« Reply #13 on: June 25, 2018, 11:51:46 PM »
The converter voltage should be at least 13.3 volts. There isn't a switch for the converter, only the 120 vac breaker for that circuit.
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John Canfield

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Re: intermittent converter problems
« Reply #14 on: June 26, 2018, 07:28:47 AM »
Find the converter/charger and check its output voltage - should be what John said.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
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Gary RV_Wizard

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Re: intermittent converter problems
« Reply #15 on: June 26, 2018, 08:17:11 AM »
Those are all unacceptable voltages if the shore power is on.   Should be north of 13v.

I can't make much sense out of those batteries readings, especially the occasional and sudden drops to the 7v range.

I also note that when the converter fan is running, the voltage comes up, but still not where it should be.

I am suspicious of the batteries - a shorted cell in one of them could have this sort of strange effect on both the converter/charger and battery voltage. A battery load test (any local auto parts or battery store can do it free) would be a good idea.

In the Parallax 7300, the converter/charger is a module inside the panel, so checking its source voltage must be done with the covers off. There should be only two wires to the battery from the 7300, i.e. a positive (hot) and a negative (ground). You can measure at the battery terminals, but check for a fuse or circuit breaker between the 7300 and the battery plus terminal.  If resent, make sure power is getting across that.
Here is the 7300 wiring guide:http://d163axztg8am2h.cloudfront.net/static/doc/d1/c4/3e9324fcdfc13a52dcbea329205a.pdf
« Last Edit: June 26, 2018, 08:22:30 AM by Gary RV_Wizard »
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Chet

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Re: intermittent converter problems
« Reply #16 on: June 26, 2018, 02:45:37 PM »
Thanks for the continued assistance... I think I measured the voltages at the places listed.  Voltages came from both measuring directly at the battery, and from inside the cover at the hot and ground wires. Glad to hear this could be as simple as a battery issue, I'll get them tested this afternoon. I replaced them last year in May, but maybe I got a bum one?
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

AStravelers

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Re: intermittent converter problems
« Reply #17 on: June 26, 2018, 02:57:08 PM »
Added a couple of comments inside the quote in red.

John's right, 30 amp shore power, 45 amp integrated converter charger.  Its a Parallax series 7300.  I monitored the voltage at both the house batteries and at what I think is the output from the converter to the batteries for a of couple hours this afternoon.  During this time, the condition I've seen camping occurred and I was able to get readings in that condition as well. 

I hit the battery boost switch, but it resulted in no change.

I don't know how to access the point at which the 120 volt power comes to the converter...

Figures on the voltmeter with three overhead lights on in the coach:

Are all these readings while you are connected to shore power?

At the batteries        at the converter to the batteries are you measuring this voltage inside the covers of the converter?
at 1800 (in mil time)
             11.98v                        11.36v
1830  lights dim, "bad" condition
            11.9v                          7.4v
hit "Aux Batt" switch, (that I was informed is the battery disconnect switch, located near the door) seemed to fix the condition...
readings went to
            11.9v                           11.6v
Yes that is the battery disconnect switch you hit.  That removed all load from the batteries.  Interesting and strange that the voltage at the converter went from 7.4v to 11.6v. 

Are these readings at 1900 and later with the battery disconnect switch turned back to normal operation?  If not you probably have a bad battery causing the problem, since all loads are disconnected from the battery, including any charge voltage from the converter.
1900     11.3v                           10.8v
1920      7.5v                              7.9v
1925 converter fan came on
              12.2v                           12.7v
2005 converter fan still on
                12.5                           12.9
Perhaps the reason the converter voltage is only 12.9v is that the converter is trying to put out near the max current it can produce, so the voltage is 12.9v instead of 13.4 because of the heavy load.  A converter seeing battery voltage at 11.3 or 7.5 should try to put out max charge current.

Thoughts?
I added some thoughts inside the quote, and here are additional thoughts.
--  It was suggested you turn on the boost switch. This switch would be very near the drivers seat. It is a momentary switch, you will have to have someone hold it on while you do your voltage tests.  It is used to tie the engine start battery to the house battery to start the engine if/when the engine battery is low.  The idea for this test is to see if the voltage comes up to 12.xx volts which would be supplied by the engine battery.
--  Get the batteries charged up, disconnect from shore power, turn on 4 incandescent light blubs (some light fixtures have 2 bulbs).  This will put a 5-6 amp load on the battery.  Now monitor the battery voltage.  If the batteries are in good condition it should take several to a number of hours hours to slowly watch the battery voltage go from 12.6v to 12.5 to 12.4v, etc.
--  Give us the size and number of batteries you have and the number of hours it takes for the voltage readings to go down and we can guesstimate how good your batteries are.

Bottom line you have unusual and very strange conditions going on.  Adding to that, they are a little intermittent.

 
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

John Hilley

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Re: intermittent converter problems
« Reply #18 on: June 26, 2018, 04:51:06 PM »
You should be able to test the converter output by disconnecting the hot lead. This will isolate the converter from the batteries and any loads. Reading should be 13.8 or higher.
2003 Winnebago Adventurer 38G
1999 Jeep Cherokee Sport
1999 Winnebago Brave 35C
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Chet

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Re: intermittent converter problems
« Reply #19 on: June 27, 2018, 12:17:47 PM »
Ok, Occam's Razor fans... tested all three batteries, (2 coach, one chassis) and found the chassis battery had a dead cell. It would test ok intermittently, but Chad who knew his batteries, determined it had a bad cell. I replaced the bad one, took out the coach batteries, cleaned them up, repainted the battery box, and replaced two cables to match the top post having gone from a side post chassis battery, then restored shore power, and find the converter/charger is now putting out 13.14 volts.  I think that's the highest reading I've seen, which hopefully indicates we found the problem! 

I'll watch it the next few days, but based on your comments of assistance... and insistence I look harder at simple fixes, I hope we got to the bottom of this challenge!  Thanks a million, I'll be in touch if the problem continues; I appreciate the collective wisdom and your patience working through this from all of you!
- C
Chet T. Motors
Shenandoah Valley, VA
2008 Winnebago Sightseer 26P

John Canfield

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Re: intermittent converter problems
« Reply #20 on: June 27, 2018, 12:42:37 PM »
Very good, I always like to go for the low hanging fruit myself when troubleshooting. Let us know in a few days if your problem has disappeared for good.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
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John Hilley

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Re: intermittent converter problems
« Reply #21 on: June 27, 2018, 04:19:40 PM »
When the batteries were tested were they given a full charge first? The chassis battery shouldn't have affected the converter/charger output unless you had a Trik-L-Start or equivalent connecting the batteries together.

Did you do a no load test of  the converter/charger with the batteries disconnected?

The change in voltage may just be a combination of fully charged batteries and cleaned connections. That converteer/charger output is still low.
2003 Winnebago Adventurer 38G
1999 Jeep Cherokee Sport
1999 Winnebago Brave 35C
  Handicap Lift & Hospital Bed