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Why is my circuit breaker tripping?

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DannyW

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Mar 10, 2020
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I have installed an off grid solar setup in my van. Everything works very nicely until I run any device 1200w+ on the inverter. This causes a 300amp circuit breaker between the battery bank and the 2000w inverter to trip.

I have tried removing everything else from the system entirely so that it is simply the battery bank (4 x 6v flooded in series parrallel) and the inverter (Victron Phoenix Inverter Smart 12/2000).

I have checked all of the cables and they appear cleanly crimped and connected at the terminals.

I have a 1000w heater that can run for a long period without tripping the circuit breaker, but if I add another 200w it will trip. Or if I run my 2000w water heater it trips after about 30-60 seconds.

I've tried 2 300 amp circuit breakers and a 300 amp fuse but all have tripped.

Any help is greatly appreciated as I don't know what else to try. I thought the 2000w water heater would only be drawing 160ish amps at 12v.
 
SolarRat said:
I was going to say a bad breaker but I guess you ruled that out. Maybe a bad inverter? Do you have a clamp on amp meter you can verify the amps before it trips?
Click to expand...

I hope it's not the inverter but I was having the same thought. I don't have one of those meters. This would be suitable right?
 
SolarRat said:
Yes, I have that exact one and it's decent for the price. Just make sure to zero it right before checking DC amps.
Click to expand...

Great, I've ordered that and will finally figure out if the current is actually too high or not. I'll report back in a couple of days.
 
2000W @ 12V will draw 166A and that is not severe by any means. 2nd Solar Rats comment, dump the crappy breaker and get a good busman one. I've read complaints on those more than once.

Bussman / cooper make "similar" looking type breakers which are knocked off by others. You will note they don't offer 300A ones, they top out @ 150A. LINK 1 below

BlueSea also offers a similar format surface mount breaker, the 187 Series goes up to 200A and anything BlueSea is top quality from my experience.
See LINK 2 below.

www.cooperindustries.com

High Amp Circuit Breakers

<p>Typically used in auxiliary and accessory circuits for trucks, buses, RVs and marine applications. Have applications in battery charging systems that use battery isolators to manage and protect batteries in multi-battery installations.</p>
www.cooperindustries.com www.cooperindustries.com

187-Series - Blue Sea Systems

Thermal circuit breakers provide heavy duty circuit protection for 25 to 200 Amp loads when switching and circuit protection are both required.
www.bluesea.com www.bluesea.com
 
Ok I've just tried running the 2000w water heater and the positive cable going from battery to circuit breaker started at 215 amps and was steadily rising up to 230 before I turned it off (could smell the fuse).

With the water heater off the cable is reading 0.8 amps.

I've tested a couple of tools 55w sander and 500w jigsaw and they are reading around 70-80% of the max rated current and not steadily rising.

Does this info give any more clues?
 
For clarity.
2000W water heater at 120 volts going to (Victron Phoenix Inverter 12/2000) which is wired Inverter <-> breaker <-> battery bank ?
 
DannyW said:
Ok I've just tried running the 2000w water heater and the positive cable going from battery to circuit breaker started at 215 amps and was steadily rising up to 230 before I turned it off (could smell the fuse).

With the water heater off the cable is reading 0.8 amps.

I've tested a couple of tools 55w sander and 500w jigsaw and they are reading around 70-80% of the max rated current and not steadily rising.

Does this info give any more clues?
Click to expand...
You have a 2000W 12V element? Or is it a 120v element running off the inverter?
 
Wow ok it appears as though there as an extra level of complication that I was not aware of.

Thanks for your help in understanding the problem. Now I suppose I look for a gas water heater (n)
 
Do you have any information in what is happening to the voltage of your battery(ies) while the amps are rising to 215+?
 
If the battery is close to the heater maybe you could use a dc heating element?
 
DannyW said:
The voltage is steadily dropping according to the inverter's app.
Click to expand...
So that might be part of your answer about why the breakers are tripping - your heater wants 2000W, your inverter needs 2000W input (plus 10%+ for inverter conversion/inefficiency maybe). Your batteries cannot provide 2200/12 = 184 amps at 12V, so the voltage drops off and the amps rise to try to meet the demand. Soon you're over the breaker limit. Just my thinking, always happy to be corrected by those smarter than me ;-)
 
Do you guys think the inverter could run this?

I'm not completely understanding the table showing cont output at different temperatures.
 
DannyW said:
Do you guys think the inverter could run this?

I'm not completely understanding the table showing cont output at different temperatures.
Click to expand...
The table shows your inverter max output drops from 1600W at 25C to 1000W at 65C
Sadly the "2000" number is more of a marketing/classification number than a number of Watts you can actually expect to see. Specs are like that, hence important to read fully.
Good luck to ya! ;-) You'll get it all figured out
 
DannyW said:
Do you guys think the inverter could run this?

I'm not completely understanding the table showing cont output at different temperatures.
Click to expand...
Nope. It needs 1500W. As you've discovered the hard way you have power for 1000W with your current set up
 
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