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h8mecz avatar image
h8mecz asked

Would SmartShunt help to control CCL?

Hello, I am still thinking how to solve my issue regarding High charge current alarms when charging the battery. It happens mostly when DC feed in grid is ON. I know DVCC is not working in this case but there are some restrictions of currents from BMS. But sometimes also when DC feed in grid is off - it this case I have 90A charging current limit in DVCC.

My batteries L1 from Pylontech have 100A maximum charging current (reading from specs and also BMS in VRM and peak 110A@15s. If I would enlarge capacity of battery - the values remain the same according datasheet. It is not like in case of US batteries where this is fine. This was my first thinking how to solve my problems.

So I was thinking if SmartShunt will be installed in my system - would it really help to system to control current limits even when DC feed in grid is on? I am asking for this because I am not electrician and not so skilled in Victron ecosystem.


Spec: PV 2x4,8kWp (south-east + north-west), 2x MPPT 250/100, 3x MPII 48/3000/35, Pylontech Force L1 battery 10,65kWh, Cerbo GX, 2x Lynx distributors.


Thanks for help guys and have a nice day!

SmartShuntPylontechcharge current limitccl
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2 Answers
Alexandra avatar image
Alexandra answered ·

@H8meCZ

The MPPT produce max for feedback but controlling where the power goes now is down to where it flows the easiest.

Adding more batteries should add to the current sinking ability of the entire bank. Especially if you wire them to a bus bar and dont daisy chain them.

You could always try a few things, one is to limit feedback to the 100A of one MPPT. As an experiment. Adding a shunt helps stabilise some systems, i have only ever added them to systems that dont have compatible batteries though.

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kevgermany avatar image kevgermany ♦♦ commented ·
Doesn't the CCL come from the batteries? Adding a shunt isn't likely to be recognised by the batteries, or am I missing something?
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Alexandra avatar image Alexandra ♦ kevgermany ♦♦ commented ·
Yes and in the case of feedback as you know is ignored.

The CCL should double if another pack is added. (One of the ways during commissioning to see if all the packs are recognised it to check if the CCL and DCL have increased). Not sure why the datasheet would say different unless it is to do with daisy chaining.

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nickdb avatar image nickdb ♦♦ Alexandra ♦ commented ·
This isn't correct. CCL isn't ignored, the CCL overide set in DVCC is. The system will always try to honour what the battery wants, and this is how it works in the field, at least with tested batteries.

The problem is when someone decides that they want to manually lower the BMS limit and export, that will not work.

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h8mecz avatar image h8mecz Alexandra ♦ commented ·
But as I said - in the datasheet of batteries Pylontech Force L1 - there is no change in the charging values even I have 3 or more battery modules :(
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h8mecz avatar image
h8mecz answered ·

CCL is from BMS. But as I wrote, somethimes there is some problem that Victron overshoot charging current and BMS call High charge current alarm and then battery is disconnected and there is no charging/discharging at all :( I would like to control charging current limit manually as in DVCC but also with DC feed-in grid is on.

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Alexandra avatar image Alexandra ♦ commented ·

Only way is to limit feed in to what the battery can sink if there is overshoot.

And cap the charge voltage so there is overhead in the cells to take it.

I didn't realise the L1 has contactors(not that I i have used them), but usually contactors disconnecting is not what shuts a system down if there is grid and solar available. I have had plenty system whose batteries disconnect and they stay on.

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nickdb avatar image nickdb ♦♦ Alexandra ♦ commented ·

Overshoots wouldn't be limited by DVCC anyway, power must go somewhere.

This does not appear to be an issue that can be tuned out. On face value it sounds like a battery or spec issue, I would open a case with Pylon for support on this.

A supported battery, sized to requirements should not need intervention manually.

Dropping CVL slightly, as suggested, may be a reasonable work around.

You issue seems to be that those 3 inverters have a recommended minimum charge/discharge requirement of 150A - as per the doc. Your 3 module L1 provides 75A, half what is needed. This outcome is unfortunately to be expected.

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h8mecz avatar image h8mecz nickdb ♦♦ commented ·

I was thinking the same to switch CVL on in DVCC. CCL/DCL from BMS is 100A so I expect this like normal / maximum current. Nevertheless it will be controlled by BMS even I would have 3x 5000W multipluses. I suppose this is an issue of BMS.....

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