Multiplus ii 5000 and pylontech

[Paul Oosthuizen]

So installing multiplus ii 5000 with 2 pylontech us3000b. Hoping to expand when budget allows to four.

Victron manual recommends 200amp fuse (sourced 3p mersen disconnect for this), and 70mm cabling. The pylons come with cabling that seems to be 32mm as far as I can establish. Inverter can run 9000w peak (which at 48v makes 190A if my maths calc is correct one). Hope I never draw that.

So some questions

Is there is any way to limit the Inverter draw say to 6000w (125a) using software

or anyone know about upgrading cabling with pylon connections to ensure they cope,.

Or will cables handle that draw which is for a limited time as it is a peak (though cannot find how long Inverter would handle that peak)

 

 

[Jaco De Jongh]

14 hours ago, Paul Oosthuizen said:

anyone know about upgrading cabling with pylon connections to ensure they cope,.

Or will cables handle that draw which is for a limited time as it is a peak (though cannot find how long Inverter would handle that peak)

No need to change the cables. 9000watt @ 48 volt will result in a 187 amp current draw. 48Volt 187 Amp on a 35mm cable over a 2 meter distance will have a volt drop of 0.496V or (1.03%).

That is way within the Recommended 3% and allowed 5% volt drop in the SANS standard. These figure means that that cable can handle that 187 amps as a constant load, so handling it as a peak or spike should be no problem at all. 

14 hours ago, Paul Oosthuizen said:

Is there is any way to limit the Inverter draw say to 6000w (125a) using software

If you run ESS on a CCGX device you are able to set the max discharge current from the battery's. Pylontech recommends 37Amp per US3000, so in your case a max dicharge current of 74amps for the 2. 

[Paul Oosthuizen]

Awesome thanks for the info

[___]

ESS will automatically limit the discharge to what the battery can handle, around 70 amps as I recall. Just turn on DVCC and the BMS will automatically limit the inverter (as long as the grid is on).

If the grid fails, then your loads determine the discharge rate. The Multi leaves the decision of whether to switch off to the BMS of the pylontech.

[deapsquatter]

8 hours ago, plonkster said:

ESS will automatically limit the discharge to what the battery can handle, around 70 amps as I recall. Just turn on DVCC and the BMS will automatically limit the inverter (as long as the grid is on).

If the grid fails, then your loads determine the discharge rate. The Multi leaves the decision of whether to switch off to the BMS of the pylontech.

This is something I still need to wrap my head around. I have the Multiplus II with ONE Pylontech US2000 Plus. I foresee a second one soon but would like to experiment a bit with one. Clearly it wont be enough for self consumption but for "keep batteries charged" mode and for use exclusively in load shedding for lights, TV it should work? I gather that with the grid off and trying to draw > 25 Amps the battery will just just down?

[___]

11 hours ago, deapsquatter said:

This is something I still need to wrap my head around. I have the Multiplus II with ONE Pylontech US2000 Plus. I foresee a second one soon but would like to experiment a bit with one. Clearly it wont be enough for self consumption but for "keep batteries charged" mode and for use exclusively in load shedding for lights, TV it should work? I gather that with the grid off and trying to draw > 25 Amps the battery will just just down?

You can always set it for self consumption with a really high MinSoC setting (90% or so). That is assuming you have PV modules and a Venus device.

The battery will allow you to go above 25A. You can go right up to 100A for about a minute or so, and 50A for several minutes, but eventually it will shut down, that's true. But the battery already tells the Venus device what the limit are, so as long as there is grid it already limits it to 25A for you.

[deapsquatter]

3 hours ago, plonkster said:

You can always set it for self consumption with a really high MinSoC setting (90% or so). That is assuming you have PV modules and a Venus device.

The battery will allow you to go above 25A. You can go right up to 100A for about a minute or so, and 50A for several minutes, but eventually it will shut down, that's true. But the battery already tells the Venus device what the limit are, so as long as there is grid it already limits it to 25A for you.

Ah I see! So while there is grid you can't overload the battery as the system will make up the difference from the grid? I'm running ESS.