Nowty Towers DIY Battery Project

[Stinsy]

At what point will you scrap the old batteries? I guess they have a very high lithium content. Do they have scarp value or are they in the pay someone to take them away territory?

They will be here for another decade or longer, or if they finally degrade too much, I will be doing a capacity test on them soon to find out their SOH.

Do you know the resistance of your shunt?

[nowty]

Update on today's discharge test using all 4 battery banks at Nowty Towers,

It started at midnight and I have burned through over half the battery capacity with over 1000 Ah's consumed with my aggressive 5.5kW export to the grid. The discharge is now heading towards zero as the solar is ramping up. The main purpose of this experiment is to measure the total usable battery storage at Nowty Towers, but there is also a fun part which is an attempt on breaking my max export record in a day which stands at 122.2kWh.

Note - The info from the Victron remote monitoring is using German time , so the graphs actually start one hour after the experiment started.

[nowty]

At what point will you scrap the old batteries? I guess they have a very high lithium content. Do they have scarp value or are they in the pay someone to take them away territory?

They will be here for another decade or longer, or if they finally degrade too much, I will be doing a capacity test on them soon to find out their SOH.

Do you know the resistance of your shunt?

Its based on 50mV for a 300A discharge.

So thats R=V/I

R= 50 / 300 = 0.167 milli Ohms

[Stinsy]

They will be here for another decade or longer, or if they finally degrade too much, I will be doing a capacity test on them soon to find out their SOH.

Do you know the resistance of your shunt?

Its based on 50mV for a 300A discharge.

So thats R=V/I

R= 50 / 300 = 0.167 milli Ohms

Cool. So about 15W then…

[nowty]

Do you know the resistance of your shunt?

Its based on 50mV for a 300A discharge.

So thats R=V/I

R= 50 / 300 = 0.167 milli Ohms

Cool. So about 15W then…

And typically more like a little over 5W as 100A to 150A is more my usual charge / discharge.

[nowty]

Gone is todays solar which was less than expected due to some quite heavy high cloud, and now its down we go, how long will the batteries last.

Current "Time to go" says 5h 43m but thats based on my optimistic estimate and not reality. Once I hit 47V, then I will read off the Ah's and that will be what I will use to calibrate the Victron SmartShunt for the usable capacity to increase accuracy of the displayed SOC.

But as the voltage drops, so does the increased Ah consumption for the same power output.

[nowty]

End of the run just past midnight, I'm going to set the usable capacity in the SmartShunt to 1758Ah to make a nice round 90kWh.
The new two battery banks may well lose a little over the first few cycles so I don't want to over estimate it.

[Stinsy]

Do you fancy decoupling your new LFP cells and finding out the capacity of the old cells?

[nowty]

Do you fancy decoupling your new LFP cells and finding out the capacity of the old cells?

Yes in due course I am going to perform a similar test separately on,

Banks 1 + 2 (LMC cells)
Bank 3 (280Ah LFP cells)
Bank 4 (315Ah LFP cells)

[nowty]

I’m currently at my mum’s so setting 24 hour exporting at Nowty Towers and the enlarged battery is still allowing all the excess generation during the daytime into the battery without any curtailment.

Nowty Towers is now a 2kWp Solar Farm with 100% capacity factor.