question

Hi i think you dont have enough battery power, minimal advice from victron is 18x us2000 so in your case minimal 12x us 3000

See: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

Part of your problem is that is way less battery than those inverters should have. With a mismatched config you are more likely to run into these issues when 24kVA of inverter (not including the peaks it is capable of) needs to pre-charge off 18kW of battery. The 3000's are light in the pants from a charge/discharge performance so this is to be expected. If you have solar chargers, turn them on first before powering the battery, it is another technique to pre-charge.

Alternatively, make sure your batteries are all online, and then connect one inverter at a time, that may be less likely to cause the BMS to wobble. Each should be isolated anyway for safety.

@kevin88252

A big precharge resistor will help.

But does not fix the ultimate problem of undersized bank and the inrush it needs. And then complicated by the low voltage of Pylons (which collapse under load as well making higher amp draws). If this is their first start and they are on the out of the box soc even worse.

In your settings don't allow the system to drian the battery bank down under 15/20% (so system shut down before the bank) to prevent future problems of having to precharge on a depleted bank. And dont start the system with large loads.

BYD have the best precharge and bank start up on the market.

Thank you guys for your replies...

About not having enough batteries:

I am almost sure that somewhere in the victron Pylontech manual i have found that 6 batteries are sufficient and i have 8?

And i can have even 20 batteries as long as they are starting up one by one, the capacitors are always charged only from the first battery and the other batteries won't help at all...

Yes, currently we start up the system either with providing AC or PV and then turning on the batteries. That works fine but is not really a good solution as it can happen that there is no auxiliary power available...

Hi @kevin88252

Can you start up the inverters one by one? It may solve your problem...

Alex

PS:

This is the joy of having low frequency inverters with big transformers inside... Inrush current.

Not the case of high frequency inverters like Multi RS. Some HF inverters even having DC-bus soft-start, but that is another discussion in itself.

You could try either of these methods. I use the 48v light bulb method with a single Quattro 48/8000 with 3 x US 3000C and 3 x US3000 to get around this exact problem

https://youtu.be/DOrJ5AH9yjM?si=h_yTjlX8l6rmVTu1

https://youtu.be/T1T1PwaTXKk?si=Ll50_wSHPOnoc5u6

Okay, thank you guys for your answers. I made a mistake overseeing that it is 6 batteries per inverter, not 6 in total.

The problem with starting one by one is i need to break the DC line and a contact that can handle that big inrush current (switching DC is always a pain, isn't it?)

I will give the system a try next week to see how it behaves under load.

The idea is to use it off grid with some PV (<1kw) and a generator. I can always start the generator if SOC is lower than 30% or load gets above 18kw...

Most of the time the load will be less than 5kw anyway.

Thanks again for explaining.

Good afternoon,

Well, the DC busbar inside the inverter has capacitor arrays, straight between the plus and minus.

When you switch off the inverter, after some time these are empty, e.g. rest voltage 4-5 volt only.

That's the inrush current you witness, with or without the inverter being switched on, nothing else.

This, LICAP SM0165-054-ATH (among other similar ones) should solve your startup problem as it can boost 2500 amp.

It also acts as just 1 extra battery and delivers between 80 and 131 amp way faster than the lithium ones at normal use.

It will therefore "protect" your lithium against these spikes and in/outrush amps as well.

Keep the cabling as short as possible to the DC busbars when mounting.

Use a 100-200W resistor to charge it, then connect to the busbars, otherwise "boom", 9000 amps.

It stores about 60Wh, yes, not much, but it will overcome a power-out, for the inverter off for about 4-5 hours, and for the inverter on at zero load for about 1-1.5 hours.

I have same and similar ones on many 24/48VDC systems, and these work just fine, a little less DC ripple and way less voltage loss/drop at high load starts, and so less overload warnings and blackouts.

At least it's cheaper than to buy 6 extra pylons for now, AND when you buy later more pylons, which you have to do, you have the LICAP as the "protector" for your system.

With regards, Jeroen.

Check me out at; https://vrm.victronenergy.com/installation/48664