question

ripper avatar image
ripper asked

Venus throttling albeit DVCC off?

I have a raspberry pi running venus for logging. I have 2x 100/20 mppts and one Bmv 700 connected to that. My batteries are 24V 180Ah.

Today was the first time it could have gone past 20A charging current. It however stuck fast at 18.2A which is lower than one mppt stan alone without venus. I m thinking it uses the BMV capacity to reduce to 10% charge rate. I thought that was a DVCC feature which I have turned off however to be able to use the smart bluetooth network with a battery sense as the pi may fail or be turned off at any time due to low battery voltage.

Can I turn this functionality off?

What happens if one Mppt is throttled down and the pi fails. Will it be stuck throttled or will it go wide open right away?


MPPT Controllers
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2 Answers
JohnC avatar image
JohnC answered ·

Hi @ripper

Why do you think it's being throttled externally? That 28.65V seems a fairly healthy Absorb V, and given the mppts may be detecting a slightly different V, and temp comp too, perhaps that's what they're targetting. So they'll throttle themselves.

You could test this (and answer your final question) by pulling the cable on the 'lazy' second mppt. The BMV should show any changes. The disconnected mppt will be independent, and work to it's own targets (with help from the Batt Sense if linked).


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ripper avatar image
ripper answered ·

Hey JohnC,

It was 6 degrees Celsius so it should have been aiming for 29.x V which it did later with less W across both. The lazy system is actually the stronger array so could have been giving an extra 15A plus. I wouldnt have thought anything about it if it wouldnt have been pretty much exactly the 10% of the capacity across both. But you are right. Shall try another day whether I can get that slacker to work. I mean the 10% would be great really, I just want to be sure I understand whats happening.

Cheers mate

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