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 > DC Power Issue

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SolanaJohn

San Diego

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Posted: 09/19/19 08:41pm Link  |  Quote  |  Print  |  Notify Moderator

Hi, I’m having a problem with DC power in my trailer. The short version is that when I turn on enough lights or appliances, the power goes off to everything. Everything works fine on shore power.

The long version: I have a 2018 little guy max trailer with a 100 watt solar panel. We bought it used early this year and the battery worked fine for the first trip (but we didn’t use much power at any one time, so it may have been a problem from the start). Here is what I have done so far to try and find the problem:

First, I replaced the battery, although it tested fine at the store. The new battery is a 100 amp-hr deep cycle wet lead acid type.

I covered the solar panels to try and isolate the problem, then:

With shore power disconnected: battery shows 12.9V. I can run most of the lights and as I turn each of them on sequentially, I can see the voltage drop at the DC fuse panel with each set of lights until the power shuts off entirely. It doesn’t matter which sequence I use to turn them off, once I have enough turned on, everything shuts off. I then turn every switch back off and plug into shore power briefly which resets everything. I can also cause the power to shut off by just using the water pump without any lights since the water pump has a higher current draw.

With shore power disconnected: battery shows 12.9V and DC fuse panel is 12.6 V.

With shore power connected: battery shows 14.6V and DC fuse panel is 13.6 V.

With shore power disconnected and solar panels uncovered in full light: battery shows 14.5V

So I conclude wiring from solar panels to battery is ok and wiring from battery to DC fuse panel is ok.

From another post, I read about a DC circuit breaker near the battery. I found it and it appears to be an automatically resetting type. Since it is between the battery and the fuse panel, I'm guessing it is ok but is there a way to test it?

Any ideas on what the problem might be or what I can check next?

Any help/advice is appreciated, I thought this would be simple but it has me stumped.

ScottG

Bothell Wa.

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Posted: 09/19/19 09:11pm Link  |  Quote  |  Print  |  Notify Moderator

When everything dies, check for voltage on both sides of the auto resetting breaker.
I suspect one side will be dead and the breaker is tripping prematurely.


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SolanaJohn

San Diego

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Posted: 09/19/19 09:51pm Link  |  Quote  |  Print  |  Notify Moderator

I connected positive voltmeter lead to battery positive and negative voltmeter lead to each side of the breaker. Both readings were zero, Does that mean the breaker is OK?

ScottG

Bothell Wa.

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Posted: 09/19/19 10:30pm Link  |  Quote  |  Print  |  Notify Moderator

No, you need to ground the neg side of the meter (battery negative or chassis ground) and connect the positive lead to both sides of the breaker in turn when everything dies. You should get +12v on both sides of the breaker.

CA Traveler

The Western States

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Posted: 09/19/19 10:58pm Link  |  Quote  |  Print  |  Notify Moderator

Quote:

With shore power connected: battery shows 14.6V and DC fuse panel is 13.6 V.
A 1.0V drop is suspicious since it appears this is with light loads. 1.0V drop is very high for a 12V system.

There have been posts about rigs disconnection from the battery when shore power is available. Perhaps yours. So lights are drawing from your charger.

Then w/o shore power you are drawing from the battery and exceeding the auto CB or it's defective, so lights out.


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time2roll

Southern California

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Posted: 09/19/19 11:01pm Link  |  Quote  |  Print  |  Notify Moderator

SolanaJohn wrote:

With shore power disconnected: battery shows 12.9V and DC fuse panel is 12.6 V.

So I conclude ....... wiring from battery to DC fuse panel is ok.
Actually
0.3 volt difference seems very high for no load. Start turning on some lights and check again.


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CA Traveler

The Western States

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Posted: 09/19/19 11:08pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

SolanaJohn wrote:

With shore power disconnected: battery shows 12.9V and DC fuse panel is 12.6 V.

So I conclude ....... wiring from battery to DC fuse panel is ok.
Actually
0.3 volt difference seems very high for no load. Start turning on some lights and check again.
X2 Was about to post the same.

Are you using different voltmeters? Could be wiring or the way you are measuring.

Need more info.

CA Traveler

The Western States

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Posted: 09/19/19 11:16pm Link  |  Quote  |  Print  |  Notify Moderator

Could be working as designed. To much draw and lights out to prevent to much battery drain. If so LEDs would help.

opnspaces

San Diego Ca

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Posted: 09/20/19 12:52am Link  |  Quote  |  Print  |  Notify Moderator

As ScottG said, test the circuit breaker poles one at a time with the meter positive on one of the threaded poles of the breaker and the negative lead on the negative terminal of the battery. Then take a reading of the battery positive to negative. You should get the same battery voltage when testing at all three places (battery positive and both poles of the breaker)

Once you have found all the voltages, have someone turn on enough loads to get the power to fail. Then go check the posts of the circuit breaker to the negative terminal of the battery. I'm betting you'll see battery voltage on the upstream (battery side) of the breaker and zero volts on the down stream side of the breaker indicating a tripped breaker.

If the breaker is tripping you can try a new breaker, they are available at most auto parts stores. But buy the same size as what is marked on the original circuit breaker, do not try to make it last longer by putting in a breaker of larger capacity.

One more thing, you'll want to disconnect or cover the solar panels so you don't get any false readings at the circuit breaker with the sun shining.


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Sam Spade

North Central Florida

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Posted: 09/20/19 06:20am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

Could be working as designed.


Sorry but that is a ridiculous answer.
He said that the water pump fails.....with EVERYTHING else turned off.
No way his symptoms are "normal".


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