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MPP inverter - fault code F51 - Over current or surge - help

Steve Fractals

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Sep 6, 2022
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MPP PIP6048MT inverter

Yesterday I installed a bank of 4 x 12 130ah flooded lead acid leisure batteries in series to give me the 48V I need. My inverter seemed to run normally and in fact I was running on battery only for most of the night without issues. It switched back to Grid ACin this morning and all seemed well. However since then I've had it shutdown with fault F51 a few times as in the title. Now I've been running the inverter battery-less for a good few months and never had a shutdown fault so clearly something to do with adding the battery bank but god knows what as like I've said it ran all yesterday and last night without issue but shutdown twice so far today and really annoyingly it isn't auto restarting even though I've put the settings in to auto restart.

Any ideas even with my limited info?
 
I don't know anything about the F51 fault code. It might be related to the fact that not only are you powering loads, but now you have to charge the battery, so the two functions combined may have drawn too much current. Given the size of your battery, charging should be limited to 20A. Recommend you set utility charging current to 20A.

However, something that is often overlooked is proper wiring of 12V in series:

Did you fully charge all 4 12V individually as 12V and again in parallel as 12V before putting them in series?

This likely has nothing to do with the F51 issue, but it has everything to do with battery health and longevity.
 
I don't know anything about the F51 fault code. It might be related to the fact that not only are you powering loads, but now you have to charge the battery, so the two functions combined may have drawn too much current. Given the size of your battery, charging should be limited to 20A. Recommend you set utility charging current to 20A.

However, something that is often overlooked is proper wiring of 12V in series:

Did you fully charge all 4 12V individually as 12V and again in parallel as 12V before putting them in series?

This likely has nothing to do with the F51 issue, but it has everything to do with battery health and longevity.
Thanks for your response. Yes I balanced the pack by charging all individually first and had set it to 20A as somewhere in the range of 10-26A was recommended by someone in the lead acid battery group with 15 as probs the best option but don't have that option and so did 20A. I've now just changed it to 10A to see if that helps although that would be a very slow charge lol. I've also got it set to Solar charging only so no AC charging.

When both times the fault occurred my house loads were less than 400w and my inverter should manage 25A (30 max) loads but the solar and AC charger and AC charger can do over 100A (120A max) but were set to 20A due to these being lead acid.

Will see how it goes at 10A charging for now and see if the fault re-occurs. To be honest I more pissed at the fact that the inverter is set to auto restart and it didn't. The 2nd shutdown happened whilst at work and so my power was out for hours until I got home so really need to get that sorted as well.
 
It definitely seems something to do with when battery starts to charge from solar at day break as the system runs fine all day but starts tripping first thing in the morning as the sun rises.

This only seems to happen if I have charge from Solar only set. If I have Solar First or Solar and Utility charging set this doesn't seem to occur but needs more testing to confirm.

For me it kind of defeats the object to have my grid charging my batteries along with solar and want to use the option of solar charge only but like I said needs more testing to confirm bid it's just that setting etc.

Been in contact with MPP but they want my life and I'm struggling to get th m as well. Manual states to plug in an OTG USB and hold ESC for 3 seconds to get into log export menu but holding ESC doesn't do anything and can't see any other way of getting the logs.
 
Page 26
Fault code 51 - Overcurrent or surge
I wonder if the fault has nothing to do with the battery being added.
What loads were on when the faults occured?
 

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  • LV6048 split phase manual-20201120.pdf
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