question

tosh avatar image
tosh asked

MPPT shut down due to a high voltage at the battery - Why?

...I'm not sure in which language I can ask my questions, so I try in English. Please excuse my English.


My question:


I installed in my mobile-home the follow:


1. Solarpanels 640 Wp, 12V

2. MPPT 70/150 Smart

3. Inverter Phoenix Smart 3000/12

4. BMV 712 Smart

5. LiFePo4 172 Ah, 12V, 14,6 V full charged


I do have the normal Schaudt EBL 102, which charges the battery with 14,7 V final full charge via power-grid or alternator.


Yesterday I set up the whole system the first time it it went well....until late afternoon. Then occures the ERR 038 at the MPPT, which means "shut down the intake, due to a high voltage at the battery".


The battery has had 13,7 V (the float voltage).

I disconnected the solar panels and the battery and after 3 minutes I reconnected all - good result. the system runs.


BUT


I cant understand the reason, why the system were gone into shutdown.

Could it be, that the charging through the EBL, which ends at 14,7 V made the system shut down, due to the parameter in the BMV of 14,6 V as Voltage of full charged?


Should I synchronise any parameters in the different equipment (BMV, MPPT)?

Does anybody has an idea, what went wrong?


Thank you in advance.


BR


Tosh

MPPT ControllersMPPT SmartSolar
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Tosh

Probably the battery disconnected due to high voltage, creating a voltage spike on the system.

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tosh avatar image tosh commented ·

Hi Daniel,

as I wrote to Spirou: the full charge voltage of the EBL is 14,7. For the battery 14,6. I cant judge, if the difference of 0,1 V could be a problem - could it?


I can change the EBL-charge characteristic to 14,4 V full charged. That would mean, that I can charge the battery with the alternator up to 14,4 and finally with the MPPT up to 14,6 V. But I have any idea, if an over-charging about 0,1 V (14,7 EBL) is worse than the under-charging about 0,2 V (EBL 14,4).


Do you have any experience in this case?


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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ tosh commented ·

I would charge even lower, like the lowest charge voltage the battery manufacturer advises

(in case of Victron LiFePO4: 14.2 volt)

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tosh avatar image tosh Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

...I got an answer from the Akku-manufatuser and he recommended to charge with 14,7, due to the fact that - different to the manual - the battery could be charged between 14,3 up to 14,7 V. With 14,3 the battery will be charged up to 90% and only with 14,7 V, the battery will be charged 100%.

So I guess, that the BMS didn’t shut down of gave a peak, that shuts down the MPPT..

I’m experimenting now charging without the power-grid and it works without any problems. Today I will add the power-grid and check, if there will be a new error.


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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ tosh commented ·

Hi @Tosh

that is very strange, I know of no other LiFePO4 batteries that charge that high, it really is fully charged at 14.2 volts (even sooner). or these have to be a chemistry that I don't know about.

But anyway, a new battery usually has to be balanced before use, and charging to max voltage will have one of the cells reaching maximum voltage before the others, and the bms has to disconnect to protect these cells.

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tosh avatar image tosh Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

...but the standard full charge voltage of the BMV 712 in the LiFePo-Profile is 14,6 V


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spirou avatar image
spirou answered ·
https://www.schaudt.gmbh/de/service-support/downloads.php
I would first take a good look at Schaudt manuals of what the correct charge setting would be as 14.7 seems excessive for LiFePO. I'm not familiar with the EBL102 so don't know what options you have.


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tosh avatar image tosh commented ·

Hi Spirou,

the EBL102 charges with IUoU, 4h. Full Charge Voltage 14,7.

There could be a problem: the battery full charge voltage is 14,6 and the EBL charges until 14,7. Could this be a problem? Do you think 0,1 V over-charging is bad for the battery?


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