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Post by Telemachus on Oct 28, 2021 21:46:14 GMT
I think if you connect the power supply to each of the 4 banks set to 3.6v or maybe 3.65v if you like, and the current is below an amp in each case, that is job done. Obviously to check, you can repeat the charge to 14.4v (having discharged a bit) and check that the cell banks are all close to 3.6v. Personally I am only charging to 14.3v and stopping charge when current falls to 5% of capacity. Because to go up to the allowed max of 14.6v adds less than an Ah (out of 600) so I don’t see the point. You only have 280Ah so in terms of Ah you would gain even less by taking it right up to the max. Cheers nick. I will try that tomorrow. I was expecting more current going in tbh. When I was balancing my 600Ah of cells, I did it in chunks of 0.5Ah (2A for 15 mins) and I think the top cell only needed 4 goes of that, ie 2Ah removed, and less for the lower cells. This is the thing about balancing, it does have to be spot on as a percentage of capacity. But then again once it is right, it doesn’t seem to drift off.
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Post by Deleted on Oct 29, 2021 8:08:17 GMT
Right. Morning arrived..... I set the voltage on the PSU to 3.6V. Attached to the first bank of 7 cells the PSU drops to 3.52 with a fluctuating current. Its been on charge for a couple of hours and the voltage at the PSU does not appear to be rising.
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Post by Telemachus on Oct 29, 2021 8:29:39 GMT
I’m not clear what the lower 2 lines of the PSU display are showing, but I don’t understand why if you set the voltage to 3.60v the display isn’t showing 3.60v. Unless you have accidentally turned down the current limiting?
Anyway I would adjust the PSU so that you are getting 3.60v at the cell terminals, and wait until the current subsides.
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Post by Deleted on Oct 29, 2021 8:32:22 GMT
I’m not clear what the lower 2 lines of the PSU display are showing, but I don’t understand why if you set the voltage to 3.60v the display isn’t showing 3.60v. Unless you have accidentally turned down the current limiting? Anyway I would adjust the PSU so that you are getting 3.60v at the cell terminals, and wait until the current subsides. One is the current, the other is power. I was under the impression the power supply voltage would rise to 3.6V when the cells are reaching fully charged. Perhaps there is too much resistance on the leads or cells, dragging the voltage down? I will go and measure the voltage at the cell terminals and report back
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Post by Deleted on Oct 29, 2021 8:34:28 GMT
3.517 at cell terminals
ETA. The top image is with no load connected. The bottom one is will cells connected.
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Post by Telemachus on Oct 29, 2021 9:12:20 GMT
3.517 at cell terminals ETA. The top image is with no load connected. The bottom one is will cells connected. So turn up the PSU until you get 3.6v at the cell terminals. But I still find the display odd. You say the top one is disconnected, and yet the current shows 9.9. Which suggests to me that it’s the current limit setting, not the actual current. And in the second shot we are seeing a lower voltage and 0.081. As if it were current limiting to a low value of current. And there is a little symbol to the right of the voltage, can’t make it out but is it cc? Edit - no I see it is cv, constant voltage, so you just need to turn the voltage up to 3.6v
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Post by Deleted on Oct 29, 2021 9:15:49 GMT
3.517 at cell terminals ETA. The top image is with no load connected. The bottom one is will cells connected. So turn up the PSU until you get 3.6v at the cell terminals. But I still find the display odd. You say the top one is disconnected, and yet the current shows 9.9. Which suggests to me that it’s the current limit setting, not the actual current. And in the second shot we are seeing a lower voltage and 0.081. As if it were current limiting to a low value of current. And there is a little symbol to the right of the voltage, can’t make it out but is it cc? Edit - no I see it is cv, constant voltage, so you just need to turn the voltage up to 3.6v Yes. It's the current limit setting set as high as it will go. Yes. The symbol CV is illuminates whilst set at 3.7V on the supply, giving 3.63 at the cells.
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Post by Deleted on Oct 29, 2021 9:16:57 GMT
So turn up the PSU until you get 3.6v at the cell terminals. But I still find the display odd. You say the top one is disconnected, and yet the current shows 9.9. Which suggests to me that it’s the current limit setting, not the actual current. And in the second shot we are seeing a lower voltage and 0.081. As if it were current limiting to a low value of current. And there is a little symbol to the right of the voltage, can’t make it out but is it cc? Edit - no I see it is cv, constant voltage, so you just need to turn the voltage up to 3.6v Yes. It's the current limit setting set as high as it will go. Yes. The symbol CV is illuminates whilst set at 3.7V on the supply, giving 3.63 at the cells. The current is fluctuating all over the place. Between 0.2A and 0.6A
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Post by Telemachus on Oct 29, 2021 9:33:40 GMT
Yes. It's the current limit setting set as high as it will go. Yes. The symbol CV is illuminates whilst set at 3.7V on the supply, giving 3.63 at the cells. The current is fluctuating all over the place. Between 0.2A and 0.6A Seems odd. But I think it’s unlikely to be the cells themselves. Either something dodgy about the power supply, or maybe the cell interconnects. Did you clean the terminals prior to attaching the links? Try checking the voltages on the actual terminals that are part of the battery, not the bits you’ve added, if you haven’t already done so. For each of the 7 cells in the bank.
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Post by Deleted on Oct 29, 2021 9:36:13 GMT
The current is fluctuating all over the place. Between 0.2A and 0.6A Seems odd. But I think it’s unlikely to be the cells themselves. Either something dodgy about the power supply, or maybe the cell interconnects. Did you clean the terminals prior to attaching the links? Try checking the voltages on the actual terminals that are part of the battery, not the bits you’ve added, if you haven’t already done so. For each of the 7 cells in the bank. Yes. I cleaned them well. It's a new power supply. I will check the terminals. Onto cell one, set at 3.7 on the psu gives full load current of 9.9A@3.5 on the terminals
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Post by Telemachus on Oct 29, 2021 9:37:38 GMT
Seems odd. But I think it’s unlikely to be the cells themselves. Either something dodgy about the power supply, or maybe the cell interconnects. Did you clean the terminals prior to attaching the links? Try checking the voltages on the actual terminals that are part of the battery, not the bits you’ve added, if you haven’t already done so. For each of the 7 cells in the bank. Yes. I cleaned them well. It's a new power supply. I will check the terminals. Onto cell one, set at 3.7 on the psu gives full load current of 9.9A@3.5 on the terminals There’s bad connections on the interconnects then.
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Post by Deleted on Oct 29, 2021 9:40:26 GMT
Yes. I cleaned them well. It's a new power supply. I will check the terminals. Onto cell one, set at 3.7 on the psu gives full load current of 9.9A@3.5 on the terminals There’s bad connections on the interconnects then. I will recheck the interconnects on cell 2. Cheers Nick
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Post by Telemachus on Oct 29, 2021 9:43:15 GMT
I think you were using the thin copper strips? Did you lightly sand the copper surfaces that were going to be in electrical contact? I think from the shop, the copper sheet may have some sort of preservative on it, or maybe the copper develops an oxide patina. Anyway, be sure to sand the copper to get a good connection.
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Post by Deleted on Oct 29, 2021 9:46:16 GMT
I think you were using the thin copper strips? Did you lightly sand the copper surfaces that were going to be in electrical contact? I think from the shop, the copper sheet may have some sort of preservative on it, or maybe the copper develops an oxide patina. Anyway, be sure to sand the copper to get a good connection. Yep. Cleaned all 144 of them. With a light sanding block
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Post by peterboat on Oct 29, 2021 10:31:05 GMT
I think you were using the thin copper strips? Did you lightly sand the copper surfaces that were going to be in electrical contact? I think from the shop, the copper sheet may have some sort of preservative on it, or maybe the copper develops an oxide patina. Anyway, be sure to sand the copper to get a good connection. Yep. Cleaned all 144 of them. With a light sanding block And then cleaned them with contact cleaner? the issue is sometimes grains from the sanding block are left on the surface and can give a poor connection. remember points on cars? if you used glasspaper to clean them up the glass could be left behind stopping them making a contact and working
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