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Old 03-22-2021, 10:12 AM   #1
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Heavy Load Appliances Flipping Breakers Despite Capable Solar Setup

Hi friends, I am running into an electrical issue with my recently-purchased converted short bus.

We have 500W of solar on the roof, a couple of huge batteries (don’t know the specs off-hand, can look this info up if it ends up being super important) and a 3000W renogy inverter.

Most of the bus runs off 12V (water pump, lights, etc) but we do have 6 120 outlets in the bus. Everything that I can find indicates that our system should be plenty capable of occasionally running heavier load appliances like a hair dryer, electric kettle, space heater, instant pot etc but every time we have tested one of those appliances it flips a breaker.

Any ideas as to what could be going wrong here? Or things to check?

Disclaimer: I did not put this solar setup together, the previous owner did, and so I am not super familiar with it, but everything appears to be set up correctly and the outlets work just fine for things like laptop chargers.

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Old 03-22-2021, 10:31 AM   #2
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Where’s the breaker?

What size and type of wire was used to wire to the outlets?

If you plug a low demand device, like a lamp with a. 60W bulb, does it trip?
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Old 03-22-2021, 10:53 AM   #3
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What size cables are used from the battery to the inverter? Are your batteries charged fully? What is the distance in feet from the batteries to the inverter? Which breaker is tripping? Is it the output 110 vac one on the inverter? If you have 110 volts present and no breaker tripping when you plug in a small electric load say a 100 watt light and then experience a breaker tripping when you plug in a high amperage load my guess is you have DC power that is inadequate.
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Old 03-22-2021, 11:08 AM   #4
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Yeah, to echo Danjo it would help to know what breaker flipped, what it was rated for, and where it is wired into the system.

Just as an observation, a 1200W (hair dryer, kettle, space heater on mid-low) load would be around 100A out of the battery. A "couple of huge batteries" doesn't really say much, if they aren't a chemistry or make favorable to solar you'll see a severe voltage drop + amperage increase chasing the demands, with ideal runtimes in the tens of minutes for something like a space heater. Even if they are, only a couple batteries still doesn't bode well for your use case even if they are in top shape, which I doubt.

Additionally, 500W will not keep up with many of the appliances you mentioned. That 500W figure is full sun, too- expecting 200W, 300W, 400-ishW much of the time... it will only take a tiny bite out of the loads you mentioned.

Finally, where are you located? Its a good idea to fill out your profile to include the make/model of your bus, engine, location, etc. You may be able to enlist a local forum member for help if needed.

Good luck!
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Old 03-22-2021, 11:10 AM   #5
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All of the appliances listed are high drain devices that probably need a 15amp breaker.

Look at the number on the breaker to see what the amperage rating is when the breaker flips, but in addition see what else turns off when it happens.

My guess is that you may have something else that’s on the breaker, like the converter/charger if you’re plugged in that’s eating some of your capacity.

If you’re plugged in to shore power try unplugging and see if it still happens.

Post a picture of the panel too.
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Old 03-22-2021, 11:21 AM   #6
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All of the appliances listed are high drain devices that probably need a 15amp breaker.
OP didn't mention anything about the breaker being AC/120V.
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Old 03-22-2021, 11:27 AM   #7
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Quote:
Originally Posted by littlebunnyhead View Post
Hi friends, I am running into an electrical issue with my recently-purchased converted short bus.

We have 500W of solar on the roof, a couple of huge batteries (don’t know the specs off-hand, can look this info up if it ends up being super important) and a 3000W renogy inverter.

Most of the bus runs off 12V (water pump, lights, etc) but we do have 6 120 outlets in the bus. Everything that I can find indicates that our system should be plenty capable of occasionally running heavier load appliances like a hair dryer, electric kettle, space heater, instant pot etc but every time we have tested one of those appliances it flips a breaker.

Any ideas as to what could be going wrong here? Or things to check?

Disclaimer: I did not put this solar setup together, the previous owner did, and so I am not super familiar with it, but everything appears to be set up correctly and the outlets work just fine for things like laptop chargers.
Sorry you're having issues. Ain't electrical fun! This is where you get to know the system, which is a good thing.

My suggestion is as you trace out your system, you diagram it for future reference.

If you can't visually inspect your wiring to assure what goes where, here are a couple of tracing tools that can really make your job easier.

AC / 120v
https://www.lowes.com/pd/Gardner-Ben...Kit/5001503345

DC / 12v
https://www.amazon.com/Fluke-Network.../dp/B000FTADX0.

These types of tracers have made my electrical work on existing systems, both house and automotive, much easier.

Per the actual problem, there's not a lot of details of how your system is set up, including specifications.

Do you have an AC Panel with breakers in it?
What breaker(s) are tripping?
What is the amperage rating of the breaker(s) that are tripping?
Is it the same breaker every time?
What other appliances are drawing from the breaker that is tripping when you plug in a large load appliance?

I'm assuming this is how it goes:

120v Outlet connected to 14 gauge wire to AC panel and breaker(s).

Breaker(s) is/are 15a or 20a
Breaker can't handle how much amperage is being asked from it, so it trips.

15a x 120v = 1800w
20a x 120v = 2400w

Your inverter is 3000w, yet there is some loss of the amount of wattage it can provide from the inversion process, so, it's maybe more like 2700w.

IF, your outlets are on one (1) breaker, and you have several loads on it, then you plug in a large load, you very easily could be overloading the circuit.

What happens if you unplug everything that uses AC and plug in the large load appliance?

Hoping this will give you some better understanding of your systems and what may or may not be causing your issues.

Best of luck.
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Old 03-22-2021, 11:57 AM   #8
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Quote:
Originally Posted by kazetsukai View Post
OP didn't mention anything about the breaker being AC/120V.

Good point, if it’s on the DC side that’s a whole nother story.
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Old 03-22-2021, 01:16 PM   #9
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The OP didn't say a lot of things.

Yet, ruling out complete stupidity on whomever installed the electrical outlets, I'm assuming there is an ac panel and breakers.

At least, I really hope there's an ac panel and breakers.
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Old 03-22-2021, 01:36 PM   #10
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Quote:
Originally Posted by rffffffff View Post
Good point, if it’s on the DC side that’s a whole nother story.
I do not know if it was tripping a 3 to 400 amp breaker on the DC side or the breaker being referenced was the low voltage shutdown on the inverter or an output breaker . Also, guessing again, if there is only 6 receps, 3 plug into one plug on the inverter and 3 more into the other one. So no sub panel. Finally , those "big batteries" are probably old 8D and not watered or fully charged. Also, that inverter requires 4/0 and a short run at best. Even at 50% say 1500 watts.

Come on OP, inquiring minds yada yada
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Old 03-22-2021, 01:50 PM   #11
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The nature of the problem, and the description of the system given by the OP makes me think it is either a DC breaker somewhere in the system or a breaker built into the inverter.

The odds of a single pole AC breaker being less than 15A are fairly low as such breakers are not really in standard use.

  • If an AC breaker 10A or less is tripping, it (and possibly the wiring off it) is undersized for the load and needs replacement.
  • If a 15A+ AC breaker is tripping, either it is faulty or the voltage on the AC side would be dropping, which is either an inverter failure or fire in the making with undersized wire.
  • Keep in mind its possible the OP is saying "a breaker trips" but that isn't actually what is happening, the inverter could be going beeeeeeeeepdead or they are interpreting some other failure as breaker tripping

My bets are, in order:
  1. DC Battery voltage is dropping well below acceptable levels for this load, upping current and tripping an appropriately sized DC breaker (Would need to be 100A at minimum, 150A ideal for the loads we are talking about)
  2. DC breaker is undersized (Less than 100A) which as said cannot support these loads.
  3. DC wiring is grossly undersized, a fire hazard.
My bet is #1 because the OP said they have "a couple of huge batteries", (so doubt on lithium) most common could be 6V in series or 12V in parallel. Case of the former: each 6V battery is getting slammed by 100A+ of draw, Latter, each 12V battery is seeing a hefty 50A draw. One of the best case scenarios is that the batteries are AGM 12V 200Ah, would put the draw at 1/4C. Worst case scenario the batteries are 6V and the draw could be well over 1C...

Overall I have little confidence the batteries are up to the task the OP is seeking.
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Old 03-22-2021, 02:00 PM   #12
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Quote:
Originally Posted by kazetsukai View Post
The nature of the problem, and the description of the system given by the OP makes me think it is either a DC breaker somewhere in the system or a breaker built into the inverter.

The odds of a single pole AC breaker being less than 15A are fairly low as such breakers are not really in standard use.

  • If an AC breaker 10A or less is tripping, it (and possibly the wiring off it) is undersized for the load and needs replacement.
  • If a 15A+ AC breaker is tripping, either it is faulty or the voltage on the AC side would be dropping, which is either an inverter failure or fire in the making with undersized wire.
  • Keep in mind its possible the OP is saying "a breaker trips" but that isn't actually what is happening, the inverter could be going beeeeeeeeepdead or they are interpreting some other failure as breaker tripping

My bets are, in order:
  1. DC Battery voltage is dropping well below acceptable levels for this load, upping current and tripping an appropriately sized DC breaker (Would need to be 100A at minimum, 150A ideal for the loads we are talking about)
  2. DC breaker is undersized (Less than 100A) which as said cannot support these loads.
  3. DC wiring is grossly undersized, a fire hazard.
My bet is #1 because the OP said they have "a couple of huge batteries", (so doubt on lithium) most common could be 6V in series or 12V in parallel. Case of the former: each 6V battery is getting slammed by 100A+ of draw, Latter, each 12V battery is seeing a hefty 50A draw. One of the best case scenarios is that the batteries are AGM 12V 200Ah, would put the draw at 1/4C. Worst case scenario the batteries are 6V and the draw could be well over 1C...

Overall I have little confidence the batteries are up to the task the OP is seeking.

I think you’re likely right, I was focused on the ac side. My other theory is that they’re plugged in and drawing load on the charger then turning on an appliance and tripping a 15a ac breaker but I think it’s more likely on the DC side. Hopefully we find out!
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Old 03-22-2021, 02:49 PM   #13
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Hi folks,

Thanks to everyone who replied! I am not at the bus at the moment, but the original owner did create a complete wiring diagram (which is in the bus), and so I will reference that and try to provide more detailed info soon.

I don't want to guess and accidentally provide false or confusing information.
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Old 03-22-2021, 03:01 PM   #14
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Littlebunnyhead, one thing you can test when you get to the bus: measure the voltage of the batteries with most if not everything off. Then try running your load that trips the breaker while measuring the voltage in the same place, look for the lowest number you read. Let us know both numbers.


Don't repeat this too often, its possible the breakers are protecting you from a more catastrophic failure.


P.S: pictures help, particularly of the breaker you are mentioning.
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Old 03-22-2021, 03:15 PM   #15
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Originally Posted by Rivetboy View Post
What size cables are used from the battery to the inverter? Are your batteries charged fully? What is the distance in feet from the batteries to the inverter? Which breaker is tripping? Is it the output 110 vac one on the inverter? If you have 110 volts present and no breaker tripping when you plug in a small electric load say a 100 watt light and then experience a breaker tripping when you plug in a high amperage load my guess is you have DC power that is inadequate.
Wow, who knew? You can quote yourself...
Good luck LBH
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Old 03-22-2021, 05:50 PM   #16
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Okay! I’m at the bus. I am attaching a photo of the wiring diagram I have, and so now y’all have all the same basic information I do. Except that I am pretty sure the previous owner said that he actually ended up using a better (thicker?) gauge of wire than is indicated on the diagram.

The second photo is of the breaker that is flipping. It has been this one and only this one both times it has happened.

The breaker that is tripping is a 250A breaker in between the inverter and the + “bus bar”. The bus bars are grounded to the chassis of the bus.

The batteries are two 12V 200 AH gel batteries by Renogy.

The inverter and the batteries are literally just a few inches from each other.

The breaker does not flip under smaller loads, and the times I have tried to run heavier load appliances (hair dryer, electric kettle) it has been the only thing that’s plugged in except for maybe a phone charger.

I can’t remember what other details y’all asked for so I’m going to go back and read over everyone’s responses and may leave a second reply.

If this info sparks further questions, just let me know. I appreciate the help!
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CAED9724-8919-4056-8DB0-C8762939CFAD.jpg   56655316-B5A6-4A74-A82D-E0CE03224CA6.jpg  
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Old 03-22-2021, 05:59 PM   #17
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tripped breakers

go directly to the inverter and see if the inverter will support the load right at the inverter.

1200 watt appliance should not trip a 15 amp breaker. amps time volts = watts

william
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Old 03-22-2021, 06:09 PM   #18
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Originally Posted by magnakansas View Post
go directly to the inverter and see if the inverter will support the load right at the inverter.

1200 watt appliance should not trip a 15 amp breaker. amps time volts = watts

william
My blow dryer says it’s 125V AC 60Hz 2000W and is running just fine, even on high, when plugged directly into the inverter.

The kettle that flipped it this morning says it’s 1200W. I haven’t tried that plugged directly into the inverter but I have to assume if it can handle the blow dryer, it can handle the kettle?
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Old 03-22-2021, 06:18 PM   #19
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Oh, looks like a couple of people asked if the bus is plugged into shore power when this is happening.

No. I have not yet plugged the bus into shore power at all, and doubt that I will have to plug it in very often as the batteries rarely dip below 90%
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Old 03-22-2021, 06:21 PM   #20
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You are feeding your 3000 watt inverter with 2/0 cable . 2/0 is adequate for a 1000 watt inverter. How far to the batteries with those undersized feeders? 4/0 feeders for a 1500 watt to 3000 watt inverter. The inverter protection breaker is 250 amps. This is way to small for a 3000 watt inverter. Put a meter on the batteries and start the inverter. How far below 12.xx volts did it sag to? My opinion is you have inadeqaute power supplied to the inverter to feed the load you are attempting to run..
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