Parallel Nissan Leaf Modules
Hi Everyone,
I completed a conversion about a month ago and have been having very weak performance. I am thinking I get maybe 3 miles on 10 module battery (36v) which is less then my lead acid on their death bed. It seems from what I have read that the batteries must have been very heavily used. I used a bms to monitor and have kept them within safe ranges (2.85-4.08, though pack voltage was 30-40.5 so they really should have never been close to the extremes). I probably have only cycled the batteries 5 times since I have been trying to troubleshoot the weak performance. I contacted the vendor (techdirect) when 3 of modules began to swell. I think I received bad batteries. The vendor is indicating the issue is my pack configuration. I have my modules in one set, with every 2 modules paralleled. The vendor indicated that format is not safe and that I should assemble two 5 packs and hook them up in parallel. This seems to me more likely to cause balancing issues and I am unclear why it would be necessary. Can someone let me know if they are correct or if I am overlooking something? |
Re: Parallel Nissan Leaf Modules
You don't still have the modules that swelled hooked up do you?!?!
That ain't safe, even when not using the cart! Read through this thread:http://www.buggiesgonewild.com/lithi...-exploded.html To be clear, this was not a Leaf module battery pack, that caught fire. It was a Volt battery pack. However, in this thread good information is shared about lithium batteries, be it Leaf, Volt or others. Maybe give us some specs on your components and pictures of your setup. The gurus on here will be able to give you advice. |
Re: Parallel Nissan Leaf Modules
Absolutely nothing wrong with the 5P2S configuration of your pack. Nick at EV Battery Center, who passed away over a year ago sold them assembled that way. My pack is 4 years old in that config and I have a 10 module pack in a cart for 3 1/2 years configured just like yours. There are many BGW users with the double configuration from Nick. The only issue with your pack may be that they sent you modules from two different mileage leaf packs. That could cause issues. When you are charging only to 4.08, I wouldn't expect a lot of mileage. You should be charging to about 4.16 and use a good BMS to prevent cell over voltage. The biggest problem with Tech Direct is that they do not disclose the AH of the modules being sold, only that they are at least 75% capacity. Nick tested all of what he sold and stated their AH and also priced them accordingly. I would gurss that most of what they sell are 55AH or less.
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Re: Parallel Nissan Leaf Modules
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https://www.youtube.com/watch?v=Jz37WycW-7E A failed BMS and over charging can do this to them but no fire. See pic. |
Re: Parallel Nissan Leaf Modules
If You can post more details about the cart itself, Controller type , Series or Sepex, tire size, etc it would be helpful.
What are you currently using for BMS and is it adjustable? Have You checked individual module pairs to make sure they are still balanced? The 5S2P you have is a better solution than a 2S5P pack they suggested, and my guess the only reason they suggested that is because that is how they sell those packs pre-assembled. |
Re: Parallel Nissan Leaf Modules
The vendor is full of excrement, there is nothing wrong with running them either way. Did you do any balancing when you received the pack? Are your cells staying in balance during use and charging or is it just a range issue? If the pack is in compression, how did the 3 show signs of swelling? There must be some serious pressures being applied to the other modules.
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Maybe we need an additional "Stickey" that is titled differently so folks don't think anyone is trying to cause panic. I've recently finished a build with 14 Leaf modules. I certainly would not have done the build if I thought it could be dangerous with utilizing appropriate safety inputs. You have way more experience and knowledge than I have and I respect that, and you. With that being said. Would you not agree that any cells that have swelled, should not be used any further? |
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