06-21-2021, 12:42 PM | #61 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
Thanks, I understand. With that said the BMS FET will fry if I try to run everything through it. I know there are some nice drawings out there on how to setup a switch to cut off the power using the BMS info, without running through the FET during operation. I will study up on it. The loose connection was confusing the curtis controller which in turned was sending out faults. I have at least corrected that problem. The individual cells for now are level +- 80 mv, and I charge through the BMS, so it will not overcharge if a single cell is low. This does not prevent, as you state, issues with LVC.
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06-21-2021, 01:54 PM | #62 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Lithium Conversion 48 volt system
I like to balance within 10mV at near full charge. I have never seen my pack anywhere near 80mV off.
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06-21-2021, 02:06 PM | #63 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
I have two cells that run 4.080 and the rest around 4.153. But its good to have some numbers to go by, I was not sure how close they needed to be. In the pack I received from Tech Direct, two of the batteries simply would not balance, so I ordered 2 more. They work much better Leaf G2, but still they are off from the rest, probably because the came from a different batch.
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06-21-2021, 02:10 PM | #64 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
Now all 14 cells are Leaf G2, just 2 are from a different batch. I did not top balance, so I may just have an offset. I thought if I left the BMS on long enough it would balance out the cells, but that did not work. I should have hooked them all up in par before I configured the battery and top balanced.
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06-21-2021, 02:24 PM | #65 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
My sources are saying the range is typically 30 mv to 120 mv.
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06-21-2021, 02:37 PM | #66 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Lithium Conversion 48 volt system
I have two carts with Leaf cells and they stay in very good balance. Many BMS are limited in balance current so it takes a lot of time to balance if they cells are out very much. You can manually balance them when you set the pack up - which is what I did initially. Then the BMS should keep them very well balanced if it's worth a ****.
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06-21-2021, 10:16 PM | #67 |
Gone Wild
Join Date: Apr 2017
Location: SE TN
Posts: 2,218
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Re: Lithium Conversion 48 volt system
You should have an option in the setup to switch to static balance. This would keep the balance circuit active all the time instead of only when charging. This should help your balance problem.
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06-21-2021, 11:15 PM | #68 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: Lithium Conversion 48 volt system
I would not leave the balance active all the time. If the pack is pretty far out of balance, I would try to manually balance it by applying a load to the high cells while monitoring the voltage. I have never had to do this but I have read about some that needed to do it once. If all of your modules are not from the same original pack, they could differ in capacity and make balancing more necessary. I always balance right after charging - "Top Balancing".
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07-20-2021, 04:11 PM | #69 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
Thanks, All is well now.
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02-10-2022, 05:38 PM | #70 |
Not Yet Wild
Join Date: Jan 2020
Posts: 39
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Re: Lithium Conversion 48 volt system
Well one battery failed on my G2 nissan Leaf setup. As shown in the picture it expanded significantly and I was not able to extract before it bent the convers on three other batteries. I am not sure what caused this failure, but the battery had been run low before I got it. With a 90 day warrenty the batteries are 6 months old and no longer covered. I had a BMS running but when the battery the entire pack dropped around 3.6 volts per cell.
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