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rickwald avatar image
rickwald asked

150/70 MPPT Trips Battery Breaker and Effectively Stops Charging (Rings)

I have had nearly the same solar configuration for three years. 900W PV into a 150/70 TR MPPT into 600 Ah of LiFePO4 in a 5th wheel RV trailer powering a Magnum 2812 Inverter. I have a second independent PV/Controller/LiFePO4 Battery Bank for all of my house 12 VDC loads. I leave the RV plugged in when it is parked at home, but I do spend at least one weekend a month and all of Summer boondocking without any shore power. My system has worked flawlessly for 3 years.

Over the past 3 months or so, I have noticed the 80A DC breaker trips on the output of the 150/70 MPPT. It is set to limit the charge to no more than 50A into the battery bank. (Though I have never seen my solar output exceed 50A even given the setting.) There are no faults displayed. It gets stuck in this mode and does not recover.

When I recycle the PV array breaker, it does begin to charge again but quickly rings between charging and shut off. See the image. When it shuts off it goes into Absorption mode but with nearly zero output. I was inside of the 5th Wheel "basement" yesterday when the 80A breaker tripped again so I was there to see the behavior. It appears to me that the MPPT is faulty. Note also that the Victron Connect App records a very low (false) Battery voltage for three separate resets I made after the 80 ADC breaker trips.

I bought all of my system components from Amazon so there is no dealer or installer to go back to.

I'm looking for confirmation that this is faulty operation as soon as possible as I need to reposition my RV for a Summer of boondocking.

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MPPT Controllers
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Alexandra avatar image
Alexandra answered ·

@rickwald

It is likely the breaker needs to be replaced. Probably some bad contact in there And all amazon sellers have a distributor that supports the product.

See here.

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rickwald avatar image rickwald commented ·

My view is that the breaker tripping is a symptom and not the cause. The ringing still takes place after both the PV and Batt breakers are reset. The breaker is not tripped when the CC output reaches a steady 48A. It must be an instantaneous output from the CC where the current output is >80A and the voltage is 2.94-4.58VDC.

I will remove the breaker and see whether the anomalous operation will continue.

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Alexandra avatar image Alexandra ♦ rickwald commented ·

All breakers have a trip curve. And can break because of thermal reasons and because of amperage reasons.

So an 80A breaker will not trip immediately at 80A.

It is likely because of running near max for so long the breaker is/has becoming faulty as it is slightly underrated as well. Since there is is usually about a 1.25 x current rating applied as well. So you should have a larger breaker there about 90A

Ringing is a harmonic possibly introduced by bad contact. Could be in the breaker contacts or connections in the screw terminals. This can also introduce heat and then thermal tripping.


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rickwald avatar image rickwald Alexandra ♦ commented ·
You are entirely correct. I replaced the 80A breaker with a 100A and have no more issues. Thank you very much.
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