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d-ferdi avatar image
d-ferdi asked

night/sunrise detection problem mppt 75/50 with firmware 1.59

hello,

i have a problem with one of my mppt 75/50 and this is the only with the newest firmware 1.59 all other have version 1.17 and one 1.19.

to get date in the night, i install a little circuit to get power to the mppt und this works fine with all mppt 75/50 only this with the newest firmware makes problem to detect the new day. i reduce the supply voltage to less then 15v in my 24V system, but this don't help, next i will try to reduce it to less then 10V.

why does the mppt don't detect a new day, if the pv-voltage is over 5v under the battery-voltage over more then 12 hours ?

i don't like it, if i must insert a circuit, which set the voltage for a short time to 0 V.

goodby

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klim8skeptic avatar image
klim8skeptic answered ·

why does the mppt don't detect a new day, if the pv-voltage is over 5v under the battery-voltage over more then 12 hours ?

It would seem that externally powering the PV input, even with a low voltage keeps the mppt awake and unable to detect a new day.

The 75-50 mppt appears to start operating at PV voltages of about 7v, YMMV.

75-50-start-up.png


75-50-start-up.png (42.7 KiB)
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d-ferdi avatar image d-ferdi commented ·
hello,

i have 7 mppt 75/50 installed and only on don't detect a new day. all other detect a new day and the pv-voltage is between 20 V and 25 V in my 24-volt-system and the mppt which doesn't detect a new day have a pv-voltage of 14V and it is the only mppt with firmware newer as 1.19 all other have 1.17 or 1.19 as firmware.

i will try to reduce the pv-input-voltage to the minimum which is needed, to get the mppt online.

i have the problem, that i lost the connection to cerbo-gx if the mppt have no power, so i install a diode and a resistor between the battery and the pv plus pole. and it works find, only the mppt with the newest firmware makes problems.

i try to sync the mppts with my software, but this mppt don't support that.

goodby

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JohnC avatar image JohnC ♦ d-ferdi commented ·

Hi @d_ferdi

I'm fascinated. Please tell us more about what you want to achieve here. You say "to get date in the night", but why, what do you mean?

Without going back through fw changelogs, it's also possible that the 1.59 is already 'alive', and fiddling with it's Vpv is preventing it doing what you actually want.



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d-ferdi avatar image d-ferdi JohnC ♦ commented ·
hello,

i have problems with the sunrise/night detection of a mppt 75/50 since i install something to prevent the device from going offline in the night because there is no more power at the pv-input. and this works fine excluded the mppt with the new firmware.

i have connected all the mppts from my 24V system over the network to a cerbo-gx and i hate it, if i see, the the device is not connected in the gx. this are old devices which are only powered by pv.

one of the mppt 75/50 is powered by streetlight in the night and have 24-25V at the pv-input and this device detect a new day without problems. only the new firmware don't detect a new day and this 75/50 is the oldest which i have.

goodby

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JohnC avatar image JohnC ♦ d-ferdi commented ·
@d_ferdi

Ahh, you mean to get 'data' in the night, not 'date'. Sorry for my slowness.

Yet you have Cerbo and maybe VRM. But I guess you have good reasons for wanting do this.

Why apply the false Vpv to the 1.59 at all? It should have separate panels to the others, and should stay alive and do what you want in standard form.

Sorry, doing this is foreign to me and probably many others, ingenious though. I work more on the style of 'update the fw and see what happens'. If you did this you can't go back. There were lots of hardware revisions on these mppts, with fw features added later too. These may/may not help, and may even hinder what you're doing.

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