John Frum
Tell me your problems
- Joined
- Nov 30, 2019
- Messages
- 15,234
For lifepo4 its about 10% from the bottom but well into the low knee.Cut off at 3.0 volts - isn't that about 20% SOC? What voltage did you charge them up to?
For lifepo4 its about 10% from the bottom but well into the low knee.Cut off at 3.0 volts - isn't that about 20% SOC? What voltage did you charge them up to?
I think my charge voltage is 28.7Cut off at 3.0 volts - isn't that about 10% SOC? What voltage did you charge them up to?
Assuming that is 10% SOC the Wh is about 2693 with a fairly mild discharge rate of 20A.
What they said:
Nominal Capacity: 2.45kWh (92.8Ah)
Energy – 100% DOD, Nominal: 2.6 kWh
EV Energy – 80% DOD, Nominal: 2.1 kWh
Both of those are good choices. I needed a little more portability and I like how easy it is to customise the victron. I sacrifice some charging power for those features but it works with my plan
This thing is really customizable. You go in advance mode and set any kind of voltage profile that you like. its pretty slick and easy to use and all the settings are customizable (well most)@No.15 Does that victron taper off well when battery is full in go into a float mode where you’ve set the parameters for charging. Can’t find much info or video on that model. I’m looking at the 24v 12a model.
Looks to have a bulk charge of a tiny bit less than the recommended 28.8v for the A123 battery but that isn’t enough to worry about.
I’m using a 30v 10 a bench PS currently but looking for a better setup.
What’s your plan for the two overkill BMS temp sensors?I finally got my Overkill Solar BMS and battery wired up. I ended up using a small PCB board to connect the balance cables to the existing connector that came with the battery.
Here's the pinout I used if you are looking at the holes of the connector. The 2nd column is the voltage I measured when I traced the wire.
Top Row Right to left
S8 26.6 VDC
S8 26.6
S7 23.3
S6 19.9
S0 GND
Bottom Row Right to left
S5 16.5
-- UNUSED --
S4 13.3
S3 9.9
S2 6.6
S1 3.3
View attachment 22867View attachment 22868
I'll probably just mount it on each end.What’s your plan for the two overkill BMS temp sensors?
Nice! I agree the range is pretty good with the bluetooth dongle. Btw, how did you mount your BMS without electrical tape lol.I removed the original sensors (3 one in the center) and wires to put the sensors in the place of the originals on the buss bar ends. I did have to extend one of the sensor wires to reach the farthest from the BMS but it was very simple. I am impressed with the range of the Bluetooth. It has no trouble even 50-100’ away out in the garage. ?
View attachment 22929View attachment 22930
Nice! I agree the range is pretty good with the bluetooth dongle. Btw, how did you mount your BMS without electrical tape lol.
Yeah I have one cell that drops lower than the pack in the lower knee. Hasn't been a problem as they all stay close through the flat part of the discharge. I also have one that is higher as the pack nears full charge. Also not a problem. I started charging on a PSU at 28.2v 10a and now the BMS doesn't reach cell over voltage (3.65) and disconnect. The battery reaches 95% SOC which i prefer.
What is your LVD setting? I set mine to 3.05V and this trips so the BMS shuts down at about 25.2VDC pack voltage.
That may be the perfect solution for your risk return curve. Others like myself may prefer something with a LVC because that is where i have had the biggest issues in the past five years. I think with used cells the risk of a cell(s) imbalance is more likely.I still say we only need a cell balancer when used indoors for off grid solar.
I'm torn. Previous posts suggest to avoid going below 3.0v. I'll try a few more cycles and hopefully it improves.Don't go by the voltage readings alone. set your lvd to 2.5 and charge to full 3.65 also set to balance during charge only.
If your disconnecting at 3.05 you won't find the full capacity.
Do a capacity test. down to 2.5mv lvd. You can set it higher later.
Have you run a capacity test yet? That will show your usable capacity.
You may have to cycle the battery a few times. Mine showed greatly improved capacity after i ran 5 full cycles.
If you go back and read thru this thread from the beginning there is alot of good advise from others on this sobject.
2.5 is for the capacity test.I'm torn. Previous posts suggest to avoid going below 3.0v. I'll try a few more cycles and hopefully it improves.