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bassman asked

Multi 2 Overvoltage on Float

Hello,

My system has developed a problem that I hope someone can provide a solution. I have Multi 2/5k/48v system with 3x genz 3kw modules (174ah). Just recently when the float voltage is reached (55.4vdc) it keeps rising (if I let it) to 62vdc when the Multi will switch off (or the battery BMS switches off??) I normally go and switch the solar off which causes the system to invert. (The GENZ LIFEPO batteries are designed as a drop in replacement for AGM etc and has no external BMS only its built in management)


The system has been fine up until recently. I tried updating CCGX and multi but to no avail. The BMV is set as recommended - Abs = 57.6, Float = 55.4.

System: Multiplus 2 5000 48vdc (An early model, Colour CCGX, VE Bus Smart Dongle and Enphase S270 (3kw) Solar on AC1 Out.

Has anybody come across this before?

Cheers - Paul


overvoltage
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Alexandra avatar image Alexandra ♦ commented ·

@Bassman

The enphase is sending power back not dialing back its production and multi has no way of controlling them or stopping them. Usually it uses a frequancy shift for AC PV (in off grid) or comms if on grid.

Do you have ESS/pv inverter assistant installed?

Move them to ac out 2 and let it switch that on and off based on needs. Or use relays and contactors to disconnect them with SOC/voltage control.

More information on how your system is programmed and set up is needed.

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bassman answered ·

Hi Alexander,

Thanks for your reply. Yes I have ESS and PV assistant. To not rely on frequency shift I have an assistant that when grid is off and batteries at 100% then the PV is switched off, then another assistant to turn them back on. This system has been working fine for a few years. This overvoltage seems to happen when batteries go to float and plenty of solar available and exporting. When the voltage rises there doesn't appear to be any charging happening or not enough to register.

Another issue I've just discovered is the VEBus Smart dongle was reporting 55vdc on absorption but the BMV (and manual measurement of batteries was 57.6vdc at absorption. The batteries were reported at 32deg C - It's been a bit warm here so that temperature charging adjustment may have confused the charger? I've disconnected the Smart Dongle to see if that makes a difference. I've read that Temperature adjusted charging for LIFEPO4 batteries is not required? Any thoughts?

Cheers - Paul

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Alexandra avatar image Alexandra ♦ commented ·
@Bassman

Do you have SVS on in DVCC?

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bassman avatar image bassman Alexandra ♦ commented ·
Hi, Yes SVS and SVT are active. Do you know what does Limit Managed Battery Charge Voltage do? SCS is also enabled.

Cheers


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