myersfamilyhome
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- Feb 9, 2021
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Update: Sorry the pic doesn't show cells connected to BMS but they are, along with connection to CC and panels. Apparently I needed all of this to activate the BMS.
I did not top balance (yet). Since all I have is a bench power supply the time it would take to bring up to a decent charge would be very long so I took away from other threads that I could let the CC bring the bank charge up where it needs to be then either use a resistor to individually adjust each cell while in series or break it all down and do blocks of 4 in parallel with the bench power supply.The cells all appear to be at the same voltage. But did you top balance them? I didn't look back through the thread to see if you did.
One parameter that stands out to me is the High Voltage Disconnect. Yours is set to 3.75 volts. I set mine to 3.65 volts. I don't charge mine to more than 3.6 volts, usually to no more than 3.55 volts. I don't recall what my Low Voltage Disconnect is, but I think mine is closer to 3.0 volts than the 2.2 volts yours is set to.
I also was looking at some other parameters of my equipment and noticed the following on my inverter specs:I did not top balance (yet). Since all I have is a bench power supply the time it would take to bring up to a decent charge would be very long so I took away from other threads that I could let the CC bring the bank charge up where it needs to be then either use a resistor to individually adjust each cell while in series or break it all down and do blocks of 4 in parallel with the bench power supply.
Regarding high voltage disconnect, I have my CC set at an absorption of 56.4 because it was recommended for long life. Breaking that down to each cell (56.4/16) it looks like my config should be set in the BMS to 3.52, correct?
Regarding high voltage disconnect, I have my CC set at an absorption of 56.4 because it was recommended for long life. Breaking that down to each cell (56.4/16) it looks like my config should be set in the BMS to 3.52, correct?
Ah, makes sense. I am diagnosed with ADHD and OCD respectively and it's easy for me to get overwhelmed with info to the point that I have a brain fart and it's all a mess. I e been trying to find the logic behind how to calculate my needs from my cells/bank based on solid #'s but not sure how to do that. I want to not cause swelling of my cells ever, make sure they last well beyond there istimated lifetime, and protect them as best as possible. If I could put all the pieces together I wouldn't be a botherNo, these do not need to be set the same. The BMS is your last chance to prevent over charging. If you set the BMS to the same voltage as the charger then the BMS will disconnect when the charger may not be done charging or the charger may need to continue the charge while the BMS is balancing. A lower value on the charger is normal. 3.65 volts at the BMS is normal.
Similarly, on Low Voltage Disconnect you want the BMS voltage lower than the inverter. You do want the inverter to stop pulling power from the battery once it sees the low voltage number. But you want the BMS to continue to be able to discharge for minor loads that may be necessary for you to troubleshoot. The inverter low voltage disconnect number should be more conservative than the BMS. For example, inverter set to 48 volts and the BMS set to 46 volts. Those are made up numbers to show the difference.
Ah, makes sense. I am diagnosed with ADHD and OCD respectively and it's easy for me to get overwhelmed with info to the point that I have a brain fart and it's all a mess. I e been trying to find the logic behind how to calculate my needs from my cells/bank based on solid #'s but not sure how to do that. I want to not cause swelling of my cells ever, make sure they last well beyond there istimated lifetime, and protect them as best as possible. If I could put all the pieces together I wouldn't be a bother
This is 1 of 2 battery banks being built. I have another 16 304ah cells for the second that I will parallel together to total 608ah@48v. I believe for a total of around 300sqft enclosed with 3" of polyiso I can heat and cool with electricity without any issue along with the little things and still stay within a safe margin of use as long as I put my settings where they are optimal. Just don't want to ever abuse them.My opinion is that cells swell because they're poorly manufactured or they were abused. Charging cells beyond 3.65 seems to be a sure way to damage them, but the damage may not be seen immediately. A compression fixture is a good way to prevent any swelling and it looks like you have yours compressed. I don't know what low voltage number puts cells in danger. My plan is to never discharge below 20%. In practice, my cells don't go below 40% under normal use. When I stress tested the system the cells went into the 30% range while staying balanced.
This is the job of the BMS. If you are battery conservative, you can make your BMS settings a little more conservative than the theoretical limits (2.5V to 3.65V). I have mine set to 2.7V and 3.63V. Set yours to YOUR comfort level.Just don't want to ever abuse them.
Can you set the low temp cutoff value to -41C?I noticed that the BMS is showing -40C on the temp output and the BMS didn't come with a temp cable.
I think the NTC thermistor is disconnected.Can you set the low temp cutoff value to -41C?
I never received one and having an issue finding one for it.I think the NTC thermistor is disconnected.
THERMISTOR BASICS – Wavelength Electronics
www.teamwavelength.com
Update: after a bit of research I believe I've found the replacement cables that will work. Will order and hopefully it will resolve
TWTADE 2 Pcs 3M 10K B3950 Thermistor Temperature Sensor,able to Support -25 to 125 Degree Celsius,Sensitive NTC Temperature Sensor Probeprobes has 5 * 25mm Stainless Steel housing NTC-3M-2P https://a.co/d/7WJjwCb
Hope everyone here is doing well and enjoying the holidays ?. I am still alive and hopefully this thread is too lol. I had to put all on hold until just recently and trying to wrap up the first bank build. Attached are pics of the cells and the default config that Daly is setup with. I was hoping to easily set the BMS up once connected but there are so many opinions on what's best that I'm still lost on what will work for my situation. Maybe y'all can help. Anything is much appreciated ?. View attachment 121780View attachment 121781View attachment 121782View attachment 121783View attachment 121784View attachment 121785View attachment 121786View attachment 121787View attachment 121788View attachment 121789