Error code: #38 - Input shutdown due to battery over-voltage, How to deactivate this feature?

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matthias-roetzer asked Jun 20, '21

Error code: #38 - Input shutdown due to battery over-voltage, How to deactivate this feature?

Hi,

I'd like to deactivate the feature "Error code: #38 - Input shutdown due to battery over-voltage" on one of my MPPT. In my application the MPPT must not short circuit the input becaus it can be dangerous in my system and could eventually hurt the MPPT. So how can I disable this feature?

Here comes a little explanation why this is important to me:

I have 4 MPPT in my 48V (lead-gel) system and are controlled by ESS. The 5th MPPT is controlled by ESS as well but has not to charge higher than 52V if ESS is off for some reason - eg GX device not working. Then the other chargers go higher than 52V and the 5th MPPT tells me Error code #38.

I came to know because I did a firmware update. usually I was doing the update at night, so there was no issue because the battery voltage was lower than 52V when ESS was not working for a minute. But last time, I did during the day, when battery voltage was higher than the fallback setting of 52V inside MPPT and boom, error #38, all fuses blown, etc. not nice....

For the time beeing I have raised the fallback setting of this MPPT to the value of the other MPPTs, in order to prevent this behaviour.

I suppose this is not yet possible. In this case please see it as a feature request. Thanks!

Best regards,

Matthias

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Answer 1 · 2021-06-20T18:49:26Z

Mike Dorsett answered · Jun 20, 2021 at 06:49 PM

Try setting the MPPT Absorption voltage to the high limit, the Float value to <=52V and the minimum Absorption time to its minimum setting. Whilst this won't prevent the error occurring, it should remove the condition that causes the short. Alternatively, you could modify the MPPT to remove this 'protection'.

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matthias-roetzer commented · Jun 21, 2021 at 12:52 PM

@MikeD Thanks for the hint. I'll try to find an acceptable setting by taking absorbtion time into account. Tampering inside the MPPT would probably mean voiding warranty. So not quite what I want to do. However cutting of the shorting circuit would be easy task, I suppose.

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Mike Dorsett matthias-roetzer commented · Jun 21, 2021 at 07:17 PM

Not so easy - and would definitely void warranty. The lids of the MPPT's tend to be stuck on with an elastomer and tend to get damaged in the removal. Alternative is to put a relay in the PV positive to isolate this MPPT when the voltage goes too high. you would need some device to drive the relay then.

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Answer 2 · 2021-07-09T03:11:24Z

Guy Stewart (Victron Community Manager) answered · Jul 09, 2021 at 03:11 AM

Hi @Matthias,

Indeed it is not possible to disable this error code, and sorry to say it is not ever likely to be made a feature to disable it.

In an ESS system if the GX device is missing, none of the connected chargers (in External Control Mode) will charge until they get the message from the GX again.

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Answer 3 · 2021-07-09T08:17:15Z

Guy Stewart (Victron Community Manager) answered · Jul 09, 2021 at 08:17 AM

@Matthias Roetzer - UPDATE

There is a built in work around to this protection if necessary.

In the case you are not using (auto) equalization you set this voltage level a bit higher, so this level will be used by the detection mechanism instead.

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