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Topic: No DC power (Read 1018 times) previous topic - next topic

No DC power

This may be an old topic but what I read left me still with questions. One question is , where do I start?
The situation is; full-timer, on shore power (50 amps) for several months, I ran the engine the other day (initially would not start, even with using the Boost switch. But, with a day on the battery charger, all was good), I have two Magnetek Charge Controllers (why two, I do not know, but this is the way it was when we bought this beast two years ago). New chassis batteries last May and new house batteries last September. (When I could not start the engine a couple of days ago, I tried the Boost switch but heard no difference in cranking speed).
My understanding is that the 'Inverter' converts 12VDC to 120 when needed when not connected to shore power, and the charge converters change 120AC to 12VDC - 14VDC to charge the 'house' batteries.
The plugs that provide 120VAC are working fine.  The things like lights (low voltage 12VDC) do not work.  All low voltage fuses are fine.  Both charge 'converters' have their usual warmth (signifying that they are working). One had stuff shoved on top to MAY have become too hot, but that is now rectified.
My step now is to check the charge in the house battery bank, as I may have a converter problem or an isolator problem, but I need to start somewhere in this problem-solving.

Ideas?
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: No DC power

Reply #1 –
Have you checked the "salesman switch" (at your door)to see if it has been kicked or bumped to off?  That may be a start to get your 12vdc lights back up. Next check the 12vdc reset breaker, some are hid on the top of the left hand wall in your service bay. I have a pic. of what you are looking for somewhere that I will hunt you if you can't find yours.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: No DC power

Reply #2 –
Quote from: Mike_Sandra_Lloyd –
My understanding is that the 'Inverter' converts 12VDC to 120 when needed when not connected to shore power, and the charge converters change 120AC to 12VDC - 14VDC to charge the 'house' batteries.
Yes, your understanding is correct - at least that is what is supposed to happen.  First thing to note: the charge controllers will only keep the "house" batteries charged.  The "start" batteries will not be charged unless someone has added a means of maintaining them while plugged in.  The usual (simplest) solution is to use a small stand-alone AC powered battery charger/maintainer connected to the start batteries.  Or, you can use a thief type maintainer that steals a little power from the "house" batteries to maintain the "start" batteries.  Search for "Trik-L-Start" on this Forum for lots of info on this and similar devices.

When your "start" batteries are extremely low, they may not supply enough voltage to activate the BOOST solenoid.  In this case, the engine may not start even if the "house" batteries are fully charged and you have the boost switch on.

It sounds to me like your "house" batteries are not being properly charged while you are on shore power, and the converters are also not providing 12volt power to operate the 12volt devices in the coach. 

You could check the voltage at the "house" battery bank with the shore power unplugged, and then check again with the shore power connected.  IF the converter chargers are functioning the voltage at the batteries should increase when shore power is connected.

If you find the "house" batteries are not being charged, then the converter chargers are suspect.  Trouble shoot as required.

If you find the "house" batteries are being correctly charged, then you just need to add some way of maintaining the "start" batteries.

The battery isolator does not enter into this discussion.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: No DC power

Reply #3 –
One other idea: check the GFCI outlet in the bathroom - see if the button is popped out.  If so, push it in and then try your interior lights.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: No DC power

Reply #4 –
The newer technology is to use a "combiner" 

If you manually connect both your battery banks they run down at the same time.

The "combiner" auto connects if either battery bank is charging if so set on its small control panel(versus full connect and full disconnect) and auto disconnects if the charging device quits charging.

Fixes the issue.

My small Solar panel (14 Watts) set puts enough power into the house side when the sun is shining to trigger the auto connect feature.


"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: No DC power

Reply #5 –
In Reply #1, Mike mentions a "12vdc reset breaker".  I think he is referring to the 90 amp breaker on the main 12V panel located under a white fiberglass cover in your middle bay (driver side).  See photo below of that panel with the cover removed.  At the top of the panel, there are 3 big round black 90 amp breakers.  The middle one is a "manual reset" breaker - the other two are "auto reset".  To reset the middle breaker, look in your utility bay for a hole drilled in the left wall near the top of the bay.  Shine a light in the hole, and you should see a reset button.  Push to reset.  (If it isn't popped out, pushing on it won't hurt anything).  See if that restores your 12V power in the coach.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: No DC power

Reply #6 –
Quote from: Chuck & Jeannie –
To reset the middle breaker, look in your utility bay for a hole drilled in the left wall near the top of the bay.  Shine a light in the hole, and you should see a reset button.  Push to reset.  (If it isn't popped out, pushing on it won't hurt anything). 

Yes that is what I was refering to. Thanks for a better explination. Here is what you are looking for on the other side.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: No DC power

Reply #7 –
Good ideas all, and the search begins! Chuck - I checked the GFI reset button first thing, so that is not the issue.  This morning I will check 'house' battery voltage and will push the manual reset button on the relay panel. (Learning something new every day!) . I will report on progress.
This issue reminds me of an old saying - "Oh, good! Another learning experience".
Thanks Team!
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: No DC power

Reply #8 –
Problem solved the easiest way! The 'salesman's switch' had been accidentally moved to the 'off' position when a bag had been pulled out from near there yesterday. DW is very happy! Thanks Pamela & Mike,  in particular.
The batteries are fully charged, so the converters are working as they should. Under the fiberglass panel I found two breakers but nothing that seemed to be a reset button. (The center did not move when pushed.
This episode has prompted me to learn more about the mysteries hidden behind the panel and I will work on that when things get a bit warmer here. (Projected minus 10C or 22F tonight).
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: No DC power

Reply #9 –
To prevent accidental turning off salesman switch, which happens often, we have a short length of flat aluminum with a bend to prevent turning switch.  Metal is pivoted out of the way to turn switch off.  Easy fix for a big  problem.

Re: No DC power

Reply #10 –
If it still has the magnetic converter might consider changing out for the newer converter that has better control of how much charge the batteries are getting. You should not need to have 2 converters, as each one charges 75 amps. Those old converters caused many a battery to be ruined by overcharging them.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No DC power

Reply #11 –
I'm surprised the chassis batteries are fully charged.  Not charging them for several months is enough to ruin them through phantom DC loads.  Maybe your salesman's switch saved them.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: No DC power

Reply #12 –
I
This coach has two chargers. One for each battery bank would make sense.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer