Lithium Cell Balancing at Nowty Towers - Resurrections

[nowty]

The Pylontech batteries only seem to be at 49.9V when measured directly, I think they internally throttle off the charging as my parallel Growatt strings were at 52.5V.

So that's 49.9V / 15 = 3.32V per cell.

My new cells were still charging but were at 3.31V so I reckoned time to install them but the Growatts were at 56.16V so there was about a 3V difference. Not quite sure about doing the final connection, but will check with a fuse and measure the current with a clamp meter.



Tiny spark and fizzle but clamp meter showing over 100A so I have decided to use my EV as a dump load to drop the Growatt Battery stack to 53.22V which should match my Pylontech + extra cell at its current voltage.

At a 5kW discharge rate of the Growatt batteries, that's going to take a couple of hours.

[Joeboy]

The Pylontech batteries only seem to be at 49.9V when measured directly, I think they internally throttle off the charging as my parallel Growatt strings were at 52.5V.

So that's 49.9V / 15 = 3.32V per cell.

My new cells were still charging but were at 3.31V so I reckoned time to install them but the Growatts were at 56.16V so there was about a 3V difference. Not quite sure about doing the final connection, but will check with a fuse and measure the current with a clamp meter.



Tiny spark and fizzle but clamp meter showing over 100A so I have decided to use my EV as a dump load to drop the Growatt Battery stack to 53.22V which should match my Pylontech + extra cell at its current voltage.

At a 5kW discharge rate of the Growatt batteries, that's going to take a couple of hours.

I know its small potatoes in the scale of things where you are operating but I meant to ask you when you last balanced your Pylontechs and is the 49.9V a single unit or multiples?

Wondering if there is room to move the soc ceiling a little higher via a balance.

[nowty]

Decided to try again at 0.75V difference and the current was about 50A, that's better, time to connect properly, remembering not to rotate the spanner were it overlaps the copper strips.


Stopped the EV charging and back to 100A charging , thereafter falling, Pylontech's charging away too.

Job done I think, just got to monitor now.

[nowty]

Decided to try again at 0.75V difference and the current was about 50A, that's better, time to connect properly, remembering not to rotate the spanner were it overlaps the copper strips.


Stopped the EV charging (dump load) and back to 100A charging , thereafter falling, Pylontech's showing they are charging away too.

Job done I think, just got to monitor now.

[Joeboy]

Decided to try again at 0.75V difference and the current was about 50A, that's better, time to connect properly, remembering not to rotate the spanner were it overlaps the copper strips.


Stopped the EV charging and back to 100A charging , thereafter falling, Pylontech's charging away too.

Job done I think, just got to monitor now.

Allow me to offer blind congratulations, looking fwd to seeing it all later. Are you still data gathering for capacity gain?

[nowty]

Allow me to offer blind congratulations, looking fwd to seeing it all later. Are you still data gathering for capacity gain?

From my spreadsheets,

I should re-gain 15% of my 48 kWh Growatt battery bank = 7.2kWh and that is a useable increase.

The new cell will be limited to the 400Ah capacity of my Pylontech bank, so just over another useable 1kWh.

So about an extra useable 8kWh for a little over £300 and that would be over £4k in Pylontech money.

[Joeboy]

Allow me to offer blind congratulations, looking fwd to seeing it all later. Are you still data gathering for capacity gain?

From my spreadsheets,

I should re-gain 15% of my 48 kWh Growatt battery bank = 7.2kWh and that is a useable increase.

The new cell will be limited to the 400Ah capacity of my Pylontech bank, so just over another useable 1kWh.

So about an extra useable 8kWh for a little over £300 and that would be over £4k in Pylontech money.

Ah man, any way you look at that, it's a complete victory, .

[Joeboy]

Heard back from Shenzhen and the quote is 1,402 US dollars for 15 of 3.2V batteries making a 200Ah pack. Included is shipping, busbars and bolts. £1,150. Would hope to do whole job for around £1,500? What do you think?

[Stinsy]

Heard back from Shenzhen and the quote is 1,402 US dollars for 15 of 3.2V batteries making a 200Ah pack. Included is shipping, busbars and bolts. £1,150. Would hope to do whole job for around £1,500? What do you think?

Are you on the hook for import duty?

[Joeboy]

Heard back from Shenzhen and the quote is 1,402 US dollars for 15 of 3.2V batteries making a 200Ah pack. Included is shipping, busbars and bolts. £1,150. Would hope to do whole job for around £1,500? What do you think?

Are you on the hook for import duty?

Probably, the quote says no tax, no vat.