Can my mppt controller drain my batteries when not in use?

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mvelden asked Feb 14, '22

Can my mppt controller drain my batteries when not in use?

Last fall I installed the bluesolar victron mppt 75/10 controller with bluetooth, using removable solar panels, all working fine. Recently after a few weeks onshore boatstorage with solar panels removed and no other charging, I found out the system batteries ( total 420 ah) were dead while there were fully charged a few weeks earlier . I wonder, could that have something to do with the power usage ( incl bluetooth signal) of the controller itself? And should I also disconnect the output connection tot the batteries when the controller not in use for a longer period? Many thanks for advise, regards Michael

MPPT Controllers

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Answer 1 · 2022-02-14T11:21:08Z

Stefanie (Victron Energy Staff) answered · Feb 14, 2022 at 11:21 AM

Hi @mvelden,

self consumption of the Blue Solar MPPT 75/10 is 25mA. That's 0.6Ah per day or 6Ah in 10 days or 60Ah in 100 days. So most likely not the reason why your batteries are depleted - unless you have a load connected to the load output of the MPPT.

If you have a Smart Solar MPPT 75/10 then it's 10mA vs 19mA (load off vs load on) per hour.

In my opinion you don't need to disconnect the MPPT from your batteries, unless you leave them uncharged for a very long time.

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marekp commented · Feb 14, 2022 at 11:49 AM

@Stefanie

0.6Ah per day

6Ah in 10 days

60Ah in 100 days

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Stefanie (Victron Energy Staff) ♦♦ marekp commented · Feb 14, 2022 at 11:50 AM

+1

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Answer 2 · 2022-02-14T11:45:00Z

mvelden answered · Feb 14, 2022 at 11:45 AM

Thanks Stefanie!! Just to check, do you know if that power usage is with or without the constant bluetooth signal turned-on, It seems to me - but not being an expert - that in the first case is it suspicously low… regards, Michael

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Stefanie (Victron Energy Staff) ♦♦ commented · Feb 14, 2022 at 11:51 AM

For the Smart MPPT that's with bluetooth. The Blue Solar MPPT does not have bluetooth.

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Answer 3 · 2022-02-14T13:20:05Z

kevgermany answered · Feb 14, 2022 at 01:20 PM

If the batteries are AGM, some could be from self discharge. But not 100% in a few weeks, unless they were pretty tired to start with.

Guess it's going to be charge, then see what the current is and disconnect circuits until you find the culprit

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Answer 4 · 2022-02-14T18:17:54Z

Alexandra answered · Feb 14, 2022 at 06:17 PM

@mvelden

Can confirm from my MPPT (75/15) using a BMV the tech specs are correct with Bluetooth running all the time.

The lead based batteries self discharge is higher than mppt consumption. I am with Kevgermany and Stefanie on this there is something wrong with the batteries. Old or sulphated or something like that, maybe not actually fully charged?

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