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john-duprey avatar image
john-duprey asked

(Solved) Smartsolar MPPT 100/50 output dropping off and on

The data sheet for this charge controller states:

1a) If more PV power is connected, the controller will limit input power.


What I am seeing is not limiting the power input, but instead turning off and then a few seconds later turning back on. With peak solar input it switches off and on often enough as to limit the charging time to about 60%, thus severely limiting the energy harvested. At lower solar inputs it still switches off and back on, but at lower frequency and yet still loses energy during the off cycles.


Is this normal operation for this charge controller or is it defective?



MPPT Controllers
screenshot-victron-100-50.jpg (381.6 KiB)
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3 Answers
Justin Cook avatar image
Justin Cook answered ·

@John Duprey, I would first go through all of your connections -including all your fuses and breakers on the system- to ensure that you don't have a loose connection or a bad/offbrand breaker that's overheating.

Every time I have seen this behavior in an MPPT, it's been caused by a bad connection/poor crimp/bad breaker or fuse that's overheating, which causes resistance in the circuit to shoot up, which makes the controller throttle itself, which lets the circuit cool off, which makes the controller start back up again, and then repeat.

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john-duprey avatar image john-duprey commented ·

@Justin Cook - Bay Marine Supply USA

Thank you, that solved the problem! There was an in-line circuit breaker as pictured. It was very warm indicating a high resistance. With that removed I'm now getting a steady 49.9A charge rate. I know I'm clipping the output of the solar modules during peak day light but that's ok.


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Justin Cook avatar image Justin Cook ♦♦ john-duprey commented ·

@John Duprey, those breakers are known far and wide for causing problems; I highly recommend that you purchase a name-brand circuit breaker that has known performance. This pretty much means either a Bussman, Littelfuse, or MidNite Solar breaker. I know these Amazon specials like you have are cheap, but in practice they offer very little protection and in fact often -as you now see- cause far more system problems than they solve.

Cheers!

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itsnotlevel avatar image itsnotlevel Justin Cook ♦♦ commented ·

Brother you just made my day. I have been dealing with this issue for a year! Thank you thank you thank you! The picture you posted could have been the exact same picture that I had in my van victron MPPT with my breaker right next to it. I took it out of service and everything is perfect, my MPPT no longer drops out and cycles power. I was a military generator mechanic / electrician, and I pride myself on being very thorough and I did save a couple of dollars by buying that particular breaker which of course I regret and have left a terrible review on Amazon for it. Again thank you thank you thank you for posting your information or else I might have been looking for a solution a lot longer.

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Rob Fijn avatar image
Rob Fijn answered ·

@John Duprey, hello. Is this MPPT connected to a smart Volt/Temp sensor via Bluetooth?
And is this MPPT part of an ESS setup ?

If so, I have see this before. I am not sure why this is, but I an think of that the MPPT is remotely controlled by the assistant in the Multi/Quattro.

Curious to hear from you.

Regards,

Rob

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wombats-rest avatar image
wombats-rest answered ·

Hi John

Was this CB connected between panel and MPPT? or between MPPT and battery? im having the same problem and have run everything direct but still having issues>

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