Nowty Towers DIY Battery Project

[pudding]

What are you charging these with? Just wondering what settings you've got for these batteries as we have the same cells. My sunsynk inverter has these settings for the batteries atm:




The pack voltage never gets that high, as one of the cells will runaway near full charge and trigger the 3.6V protection and stop the charging (I think i set 3.6V in the Seplos settings rather than 3.65V). Should I be setting lower voltages so that a cell wont runaway and the Seplos stops the charge, so that the inverter can keep on charging?

[Stinsy]

What are you charging these with? Just wondering what settings you've got for these batteries as we have the same cells. My sunsynk inverter has these settings for the batteries atm:




The pack voltage never gets that high, as one of the cells will runaway near full charge and trigger the 3.6V protection and stop the charging (I think i set 3.6V in the Seplos settings rather than 3.65V). Should I be setting lower voltages so that a cell wont runaway and the Seplos stops the charge, so that the inverter can keep on charging?

Float, absorption, and equalisation are relevant only to lead acid. You can use an inverter set to lead acid to work with LFP if you want just set all 3 to the same voltage. Typically somewhere between 3.35-3.40V per cell (53.6-54.4V on a 16s setup). Some battery manufacturers specify higher voltages but you’re cooking your batteries for teeny amounts of additional capacity.

[nowty]

What are you charging these with? Just wondering what settings you've got for these batteries as we have the same cells. My sunsynk inverter has these settings for the batteries atm:




The pack voltage never gets that high, as one of the cells will runaway near full charge and trigger the 3.6V protection and stop the charging (I think i set 3.6V in the Seplos settings rather than 3.65V). Should I be setting lower voltages so that a cell wont runaway and the Seplos stops the charge, so that the inverter can keep on charging?

You should not be getting a cell running away to 3.6V unless your balancer is not working correctly. My active balancer I use on my LMC cells keeps them within 5mV but I don't push them too high. The problem with some balancers is they only balance at the top which is too late in some cases.

So yes I'd say you need to lower the voltages, even 55.5V is about 99% SOC, do you really need that extra 1% ?

My system is more complicated because I am charging different battery banks with different cell numbers and different chemistries, so for me its all about some sort of compromise at both the top and bottom ends.

I set my system charging to Lead Acid mode, turn off EQ and temp compensation to zero. Then I set Absorption, Float and EQ at the same Voltage, it does take longer for absorption to complete but I'm happy with that.

EDIT - I did not notice Stinsy replied, yes I think I have repeated what he said.

[pudding]

Thanks both, will lower all voltages there. Not sure if they're actually used as the inverter is set to lfp battery not lead-acid, so if they're not, maybe the inverter gets the charge voltage from the seplos bms and I'll need to get back in there and check? Cheers.

[NoraBatty]

I’ve seen 3D printed terminal/busbar covers. Are you planning to do something along those lines? I’d be terrified of an accidental short…

Generally no, its in an inaccessible place, but I will be protecting the power take off points, they really scare me if the upper terminal post was to fail and the upper bus bar was to slide down. But probably no drama as the forklift fuse would blow.

Have you thought about kapton tape over them Nowty?!
Not perfect for protection compared to a full blown cover but takes most what ifs out of the equation and very easy to apply and remove.

[nowty]

Have you thought about kapton tape over them Nowty?!
Not perfect for protection compared to a full blown cover but takes most what ifs out of the equation and very easy to apply and remove.

I'm thinking more about a plastic slip on cover like you can get for live bus bars in AC consumer units, I just have to find one with enough depth to cover the 20mm wide DC bus bar.
https://www.screwfix.com/p/british-gene ... 70mm/1940p

[AGT]

Appreciate the reply to my earlier post!
All makes sense now

[AGT]

Have you thought about kapton tape over them Nowty?!
Not perfect for protection compared to a full blown cover but takes most what ifs out of the equation and very easy to apply and remove.

I'm thinking more about a plastic slip on cover like you can get for live bus bars in AC consumer units, I just have to find one with enough depth to cover the 20mm wide DC bus bar.
https://www.screwfix.com/p/british-gene ... 70mm/1940p

Or some heat shrink?

[nowty]

Have you thought about kapton tape over them Nowty?!
Not perfect for protection compared to a full blown cover but takes most what ifs out of the equation and very easy to apply and remove.

I'm thinking more about a plastic slip on cover like you can get for live bus bars in AC consumer units, I just have to find one with enough depth to cover the 20mm wide DC bus bar.
https://www.screwfix.com/p/british-gene ... 70mm/1940p

Or some heat shrink?

Yes, of course thats what's on the standard single busbars that come with the cells.

[nowty]

Battery balancer is now ready for fitting, I have used masking tape over the exposed ends and marked each one with a number from 0 to 16.



They will connect in number order starting at the negative power bus bar as in my marked up diagram below.



Its difficult to make the balancer wiring look neat but they are now connected, the balancer is just sitting on top of the batteries behind the top threaded bar cover. The largest cell difference was about 100mV when the batteries were near fully charged. I will check again in a few days to confirm that has dropped to nearer 5mV.