Run a 302AH with a 24v Overkill BMS?
- Thread starter Merlin
- Start date
That will work, within the restrictions that Bob said in the above post.
Thank you for the quick reply your both.
The battery would charge with maximum 80amps on 24v.
Discharge the battery is just like 50 amps I guess most of the time may 30amps
So did I understand right that I don't need worried about?
Than I would buy that CATL 302ah cells with the 24v overkill BMS.
The battery would charge with maximum 80amps on 24v.
Discharge the battery is just like 50 amps I guess most of the time may 30amps
So did I understand right that I don't need worried about?
Than I would buy that CATL 302ah cells with the 24v overkill BMS.
The BMS doesn't really care what the Ah rating of the battery is. It could be 50 Ah or 500 Ah. You can set the Ah as one of the parameters in the BMS configuration.
Bob B
Emperor Of Solar
- Joined
- Sep 21, 2019
- Messages
- 8,633
You should be fine at those amp loads.
Perfect. Thank you so much for your help.
I have another one issue or just a question.
I got my 16 x 280ah cells 3 weeks ago perfect match from BASEN.
Yesterday I started building my battery pack. First I put them in parallel and try to charge it with my 5 amp bench charger.
The cells was at 3.295v at this time. I wait 2hours and nothing happened on the voltage how I guessed before.
Than I put all in series to build a 48v battery and wanted to charge them up so far I can.
(Because Will says in his top balancing video. After that back in parallel and charge them up to 3.6v)
So I build the 48v pack and put the BMS 48v overkill on it. But I made maybe a mistake. I put the first negative on the main negative than on all next positiv pole till the last Red Wire to main positive. Check all voltages on the cable. It was all good. 3.29, 6.40, and so on.
After that I connect the white and the black cable bank on the BMS.
I have a look on them and 3 or 4 cells showing me with roughly -0.07v means completely empty.
I took them all out right away.
I connect all wires new! Exactly like the manual from overkill.
Connect them again without the blue cable and the red load cable to the batterie. Now 2 or 3 cells was not correct showing me.
I connect my charger and all cable and it does work. Showing me all cells as the correct voltage.
So than I charge the battery up to 17h. 7h with 10amps and 10h with 18-22amps.
I set all the settings standard, 280ah nominal and 224ah cycle, the BMS was not show me any errors or other issues, all normal. But....
Now here my concerns:
So I load the battery, the capacity shows me at the first time 134ah with 3.29v, than I reset the capacity one time, than shows me 250ah in the battery. I thought 134ah it's a way to less for fresh delivered cells.
I started the charging. After couple hours was 280ah reached. But charging further, I reset the capacity again. Than shows me 170ah. Reset again, shows me 260ah. I charged them further. I did that maybe 6 times again and it jump everytime back on 260ah.
Know I had 272ah and doesn't jump back a anymore. Two cells reached 3.65v now. The rest still on 3.390 roughly. Put them back in parallel and load them full to 3.60v further.
Now my questions, is this all normal what happened? how you can see attached the pictures, all the time the cells are in yellow range and the half of the display like 50%. Just shortly before that 2 cells reached 3.5v the colour changed to green. But not the whole box. I saw many videos, on all that videos the colour was green.
Please ha e a look on the pictures.
Did I killed my BMS in some way? Or a wrong setting or what can be the reason for that?
Very appreciate that when you guys have some answers for me.
Thank you a lot in advance.
I have another one issue or just a question.
I got my 16 x 280ah cells 3 weeks ago perfect match from BASEN.
Yesterday I started building my battery pack. First I put them in parallel and try to charge it with my 5 amp bench charger.
The cells was at 3.295v at this time. I wait 2hours and nothing happened on the voltage how I guessed before.
Than I put all in series to build a 48v battery and wanted to charge them up so far I can.
(Because Will says in his top balancing video. After that back in parallel and charge them up to 3.6v)
So I build the 48v pack and put the BMS 48v overkill on it. But I made maybe a mistake. I put the first negative on the main negative than on all next positiv pole till the last Red Wire to main positive. Check all voltages on the cable. It was all good. 3.29, 6.40, and so on.
After that I connect the white and the black cable bank on the BMS.
I have a look on them and 3 or 4 cells showing me with roughly -0.07v means completely empty.
I took them all out right away.
I connect all wires new! Exactly like the manual from overkill.
Connect them again without the blue cable and the red load cable to the batterie. Now 2 or 3 cells was not correct showing me.
I connect my charger and all cable and it does work. Showing me all cells as the correct voltage.
So than I charge the battery up to 17h. 7h with 10amps and 10h with 18-22amps.
I set all the settings standard, 280ah nominal and 224ah cycle, the BMS was not show me any errors or other issues, all normal. But....
Now here my concerns:
So I load the battery, the capacity shows me at the first time 134ah with 3.29v, than I reset the capacity one time, than shows me 250ah in the battery. I thought 134ah it's a way to less for fresh delivered cells.
I started the charging. After couple hours was 280ah reached. But charging further, I reset the capacity again. Than shows me 170ah. Reset again, shows me 260ah. I charged them further. I did that maybe 6 times again and it jump everytime back on 260ah.
Know I had 272ah and doesn't jump back a anymore. Two cells reached 3.65v now. The rest still on 3.390 roughly. Put them back in parallel and load them full to 3.60v further.
Now my questions, is this all normal what happened? how you can see attached the pictures, all the time the cells are in yellow range and the half of the display like 50%. Just shortly before that 2 cells reached 3.5v the colour changed to green. But not the whole box. I saw many videos, on all that videos the colour was green.
Please ha e a look on the pictures.
Did I killed my BMS in some way? Or a wrong setting or what can be the reason for that?
Very appreciate that when you guys have some answers for me.
Thank you a lot in advance.
Attachments
Verify all your connections. Cell voltage issues are often caused by bad connections.
Could be that really just the reason? And should the colour definitely green at 3.3v?
Most of your cell colors look yellow to me.
I would expect green at 3.4 volts. But I haven't looked at mine lately to see what color they are.
In my limited experience, the BMS doesn't report an accurate SOC until the battery is fully cycled. Even if the capacity is reset. All of my bars are yellow but I am charging to 3.385 volts.
Regarding your high voltage difference have you measured the voltage at the cells with a DVM and compared to the readings displayed by the BMS? As HRTKD said, the high delta is most likely due to bad connections.
I see, that can be. But otherwise I use a 24v battery with a overkill as well, maybe 2 weeks now. I don't discharge the battery completely, means 2.5v. Just until 3.1v. I charge the battery just with the solar may 3 or 4 times. The BMS show me until today 0 cycles.
I have the same issue there. Yellow bars as well. I don't know what can be the issue. I've seen a video on yt from the "offgrid garage" , His phone with the same app shows all green bars at 3.371v for example.
Can that be that the BMS is running and have properly a defect as well? Or if the BMS is defective can't work at all?
And if I made the decision that I send the BMS back to overkill. Need to order a new one and pay again for it or just send the defective BMS back and become an exchange? Sorry that I ask here, because Steve doesn't text back, I guess he had lots of things to do.
Thank you all very much for your help!
Thank you all very much for your help!
I mean yes you have normally right. But why are bars on other yt channels always green for example from a cell voltage 3.34 or 3.37 and in my case the bar get a green colour from 3.5 roughly? And the bar is just 70% in green and the rest of the bar still white? Something is different.?
Verify the YT voltage settings are exactly the same as yours for cut off, cell balance start, full charge etc.
Appendix A of the manual says the standard full charge voltage is 3.500 volts. I assume you need to hit that to go green. If you expect to charge to just 3.4 volts per cell and call it full you may want to adjust this setting.
Appendix A of the manual says the standard full charge voltage is 3.500 volts. I assume you need to hit that to go green. If you expect to charge to just 3.4 volts per cell and call it full you may want to adjust this setting.
Last edited:
First you need to solve your delta problem. With your lowest cell voltage at 3.339 and your highest cell voltage at 3.648 there is no way you are fully charging the battery. My guess is you are only charging to apx. 85% capacity. You need to fix that then fully cycle the battery. The BMS counts cycles every time you pull 224ah's. from the battery.
Did you verify your cells voltages with a DVM to see if it matches the readings on your BMS like I suggested?
I don't believe that's an issue. Some of us have never seen green bars and like I said I haven't charged more than 3.385 volts since I updated the app.
