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kimsan avatar image
kimsan asked

Multiplus II tripping Battery Protect on a separate circuit when connected to battery + on load spike

I have a Winston 300A 24V battery bank used for both 24V equipment (lights etc.) and 230V eqipment. The 24V part is protected by a 65A Smart Battery Protect. A MultiPlus 3000/24 is used to provide 230V.

The problem is that the BatteryProtect on the separate circuit is tripping when I connect the MultiPlus II to the battery bank (by the red switch, with rocker swith in 0 position). The BatteryProtect resets after 90s and returns to normal. There is no error messages from either the 123SmartBMS or the Battery Protect. I'm not on site now, but I will measure with an ocillioscope in the weekend to better quantify any voltage fluctations.

A (little) simplified sketch of the system is enclosed below.

Do anyone have a good explanation on why the BatteryProtect is tripping?


victron-multiplus-and-batteryprotect.jpg

Multiplus-II
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3 Answers
klim8skeptic avatar image
klim8skeptic answered ·
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snoobler avatar image snoobler commented ·
I agree on the need for a pre-charge circuit, but why would that cause the BP to trip?


Do you think the BMS is sending a cut-out signal to the BP due to short circuit protection? The inverter functioning with no BMS errors would suggest that's not happening.





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klim8skeptic avatar image klim8skeptic ♦ snoobler commented ·

Do you think the BMS is sending a cut-out signal to the BP due to short circuit protection?

A guess would be that the BMS has tripped the allow to discharge op due to current surge or brief cell undervoltage. BP could also trip due to battery undervoltage.

At least the OP will take a resistor on site.

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kimsan avatar image kimsan commented ·

Thank you, I'll add one resistor to the setup. As other people have to be able to connect it as well I think I have to add it over the switch permanently using a spring switch.

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nebulight avatar image
nebulight answered ·

Could the smart123 bms see the inrush current of the inverter and shut down all loads as an over current protection? I'm not totally familiar with the smart123 but if it has over current protection, that could be it.

That would explain why the smart battery protect would be shutting down (via remote to the BMS)

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kimsan avatar image kimsan commented ·

The 123smartBMS doesn't have any surge protection, and it doesn't log any issues (I think it have an delay on such event). However, it could be, as stated above, that the BP is tripping due to low voltage. I'll add the resistor to hopefully solve the issue.

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kimsan avatar image
kimsan answered ·

Precharging of the MultiPlus went well, thank you all for the help. However, I found a new problem while using the MultiPlus over the weekend.

I did some short and long time load test of the multi without any issues. However, when I connected a 65W HP charger (not connected to any load) it tripps the BatteryProtect (you can hear a little spark when the socket is plugged inn, and that's when the BP tripps).

I did measure over the battery with ocillioscope and couldn't detect any voltage fluctations at all. When I was measuring over the relays I wasn't able to get it to trip, and I ran out of time this time as it took quite some time before the charger was empty for re-testing.

Again, not any of the equimpent throw any error messages.

hp-65w-charger.jpg



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