question

kaarthik avatar image
kaarthik asked

pylontech not reach to 100%

Dear all,

sensed voltage of battery and battery BMS voltage is not same so it doesnot charge the battery to 100%.Battery actual voltage is lesser but multiplus sensed DC voltage is higher so multiplus stop charging the battery.please find the attached screen shots.pylontech US2000 with multiplus II 5kVA UNIT.multiplus.pngpylontech.png

Pylontech
multiplus.png (31.4 KiB)
pylontech.png (214.4 KiB)
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2 Answers
nickdb avatar image
nickdb answered ·

You need to start by manually checking all your wiring, connections, fuses etc with a meter to see where the voltage loss is originating. There is always a little loss, but when it is above average, it almost always is caused by something in the wiring chain.

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kaarthik avatar image kaarthik commented ·

Dear sir,

if its loss then victron inverter sense voltage should less than that pylontech battery voltage , but here its other way around inverter sense voltage is greater than the battery voltage.

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nickdb avatar image nickdb ♦♦ kaarthik commented ·

No, the inverter will be higher as it is the charge source. The battery is lower, ie there is loss on the way down to the terminals.

Chart the different voltages over time and across higher and lower load. You should find it increases with load.

You can use a custom widget for this. Like so.

screenshot-2022-10-01-at-113540.png

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kaarthik avatar image kaarthik nickdb ♦♦ commented ·

Dear sir,

thanks for the information i will check.

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Alexandra avatar image
Alexandra answered ·

@kaarthik

This is quite a common behaviour of Pylontec to reach close to 100%

It is mentioned in the Victron Pylon page. It has alot to do with their internal cell balancing as well.

It does get there eventually. We have quite a few systems in place now, so have seen the behaviour.

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kaarthik avatar image kaarthik commented ·
Dear sir,

It won't go more than 90% for more than 4 weeks.

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Alexandra avatar image Alexandra ♦ kaarthik commented ·

Your Pylontec picture shows 98%.

51.8v is just over float voltage. Ar this piint of charge what may be happening is the system is dropping the battey to float voltage at 51v. so the percentage will drop a bit. 52v is considered fully charged.

The multiplus is on external control, also shown in your multiplus picture, so the battery is controlling the system.

Set your system to keep batteries charged and wait for it to balance out.

Your batteries are at 29°C that is quite hot. The bms could also be changing its charge to suite the temperature which is not uncommon for lithium based batteries.

How many batteries do you have?

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