EasyStreet
I used to be a somebody ...
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- Sep 17, 2020
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Nice. That would be best. If I were doing a bunch of batteries I would do the same thing.
Ordered 4 cells 280ah From Shenzhen Basen, CN
- Thread starter Oldtoad
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Nice. That would be best. If I were doing a bunch of batteries I would do the same thing.
MadMax03
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- Sep 21, 2019
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This is the future. Pump 280 amps into those suckers and not hurt them.
I did a while ago, but I ran into an unforseen snag
diysolarforum.com
I did a while ago, but I ran into an unforseen snag
6S3P 120ah LTO Build
Quick, short thread of an LTO build for car stereo. Not much to it, but wanted to start original thread instead of cluttering up someone else's. May have a few visual clues about process/procedure for others in the future. Cells came from Shenzhen, fairly well matched at around 2.28-30v each...
diysolarforum.com
How thick are these bus bars? I have similar cells except mine are 90Ah. I pulled 900W at 12V with DIY copper pipe bus bars and the bus bars got extremely hot. Used 1/2 inch thick copper pipe and hammered it flat so they aren't terribly thin. I'm shocked at how hot they got.
Wow okay. I've seen plenty of people with the same cells on YouTube do capacity tests with the factory included buss bars and I'm unsure how they don't have the same issues. I'm having voltage drop issues even with my new bus bars
Can you post a photo? How thick are they? Where exactly are you seeing the voltage drop and how much? A 2mm thick busbar would easily be able to handle 75 amps. Also they need to be flat against the cells terminals.
Here's a picture. The bus bars are 57mm wide and 3.2mm thick. Pretty hefty as you can see. The copper pipe is hammered flat. Voltage is dropping from ~13.3V resting no load to ~11.5V under a 900W load. Since I received my cells (ordered brand new) I have always experienced voltage drop even when using the stock bus bars (stock bus bars were thin and junky).
I do have a coulomb counter w/ a shunt so I can confirm the battery is just about fully charged.
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The busbars are hefty but they must be flat against the battery terminals. Are they? If only a part of the busbar is making connection with the battery terminal then it could explain the voltage drop and heat. The bulk of the current travels from the battery terminal through the busbar, not the screws used to mount the busbars.
Yes they are flat. I wouldn't say ~perfectly~ flat but they are making a solid connection. Might need to try a perfectly flat copper bar instead of hammered pipe.... unfortunate these DIY bus bars may not work.
MadMax03
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- Sep 21, 2019
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Those look like a 6 year old made them. Don't skimp. Go get some 1/2" x 1" or whatever alunimen flat stock and make some nice bars. Nothing wrong with matching metals in terms of conductivity, and in fact, you are even further delaying galvanic corrosion using like metals.
If they are not perfectly flat and covering the whole terminal then that would explain the problem. If the bottom looks anything like the top that's not good. I know you said you had voltage drop with the included busbars. Did they heat up too? Also you have 90 amp cells and I assume they are good for up to 1C rates?
Haha I know the bus bars are not the most aesthetically appealing. I will go the 1/0 cable route and update everyone what happens. Thanks so much all for the advice.
I can tell you that even silly things like an unpolished terminal will cause major problems. You need a VERY clean set of surfaces and perfect contact. 1000-grit sandpaper on the terminal and connections, wipe clean with dry rag, wipe with de-ox solution, and then assemble. If you're going to use bare copper against the aluminum terminals, use very small amount of anti-ox between the terminal and the copper. At those loads you need near perfection.
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