question

cms avatar image
cms asked

MPPT Failure mode?

AnMPPT controller (Furrion) failed on an RV and sent array voltage (96V straight to the LFP battery bank. the /BMS could not protect against 96V so the cells swelled, blew the metal battery case open and started smoking.

Question:


In a failure of the controller is there any way a Victron MPPT could ever allow this to happen?


From what I understand the input/output of aVictro MPPT is fully isolated ?

MPPT Controllers
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4 Answers
Alexandra avatar image
Alexandra answered ·

@CMS

Never seen it happen with Victron. The mppt sacrifices itself. And I have seen some pretty big mistakes happen. Victron treat the battery as the heart of the system.

Look through the error codes. You will see almost all of them occur because the mppt is protecting the battery. Error 40 is just one as a specific of an occurrence where it will self sacrifice to prevent battery damage.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Many years ago I had this with a Victron PWM controller but never with a MPPT.

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Mike Dorsett avatar image
Mike Dorsett answered ·

No, the MPPT is not fully isolated. This is a switch mode converter, using a synchronous rectified buck topography.

From my look inside an MPPT 100/50, it is possible that a single component failure - the high side Fet switch, would conduct the PV to the battery through the inductor and some current monitoring circuit.

However, having said that, I know of no "fully isolated" mppt chargers - they would be considerably more expensive to produce.

A properly designed system should have a PV disconnect relay in the INPUT (PV) side of the MPPT, controlled by the BMS. Thus in the unlikely event of a switcher failure, the BMS would be capable of disconnecting the PV from the system.

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mondeoman avatar image mondeoman commented ·
Victron's SmartSolar MPPT RS 450V is fully isolated.
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anthony-daube avatar image
anthony-daube answered ·

That is interesting as we have a 2 solar panel with a 100-30 Victron MPPT, the MPPT failed and allowed the voltage of the PV to go to the Lithium batt, which the BMS shut the battery off. The 24vdc house load (boat) received 51 vdc destroying all equipment attached. Has anyone seen that before?

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Alexandra avatar image Alexandra ♦ commented ·
Likely scenario is the battery shut down suddenly the production over voltage spike had to dissipate into other consumers.

Use dc spd for loads next time.

Is the MPPT actually returned for an RMA?

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