Recent content by youyoung21147

@TilmanBaumann The most optimized way to charge LiIon cells is to use constant polarization voltage (20 to 100mV). All EV manufacturers use this method as the base for their charging algorithms. That's why the LG datasheet is so specific about SoC vs OCV. Betwwen 10 and 30% SoC, the cells can...

Hello, I just came across these 2 datasheets on QB's website. Both are clearly addressing the EV and residential storage market. E63 is ~240Wh/kg and C1.5S is ~170Wh/kg. It seems like the 65Ah model is the current (or future ?) Renault Zoe battery cell : the datasheet explicitely mentions 22...

What I did on my 10S and 14S ebike packs is varnish the entire pack internals and close the ends with wire mesh. This allows air circulation in the pack and repells big debris. Rain/water can get in and out. Tested for 1 year without trouble and no corrosion ! Airflow is critical to quickly...

Considering the effort you put in making these packs and the safety risks, I would first learn how to make a pack properly. You seem to have good DIY skills so here are some guidelines : - Cells must NEVER touch each other. Use spacers ("battery holder") instead. That's to prevent overheating...

@ElectricGod : your conclusion reach mine ! These cells are overpriced and useless. I think they are 35E chemistry fitted in a larger case : when you normalize numbers and curves proportional to the cells mass, you get the same (=poor) cycle life and slightly more saggy discharge curve. When...

@tomjasz I have bought these cells from Tumich last year. I put one in accelerated testing 4.01 to 2.8V /6A. After 1100 cycles it was still giving >2800mAh under manufacturer test conditions. And in real life, my commuting ebike that has seen approx 60 cycles in a year still outputs 95% of its...

@ElectricGod : good to see you took the plunge on these. What decided you on the 21700 format ?

Do you have cycle life test data for HG2 cell ? I've performed some tests of Samsung 30Q cell but not HG2. Not great cycle life but no degradation of internal resistance over time. I tested 30Q in priority based on this test (quite extreme ! cells reached 80C)...

Nice link ! Will watch the video in full when I have time. I've seen a few papers about EIS testing for various Liion cells evaluation purposes, including online SOC estimation. It's beyond the effort I am willing to put in my personal testing. These tools must be really valuable to battery...

I stopped testing at ~1100 cycles. Interestingly the capacity retention under manufacturer's testing conditions is excellent. Less than 15% degradation in 1000 cycles. For LG MJ1 the Coulombic capacity degradation is predominant For Sanyo GA the internal resistance degradation is predominant...

In my testing the cells are charged at 1A (0.3C) CC-CV to 4.19V and CC discharged at 9A down to 2.8V, then CV discharge down to 3A/2.8V. The tester is a fully calibrated iCharger 4010. The test method is not conventional, because I tested these cells for a very specific use case. But what I...

35E has very very bad cycle life ! And it sags a lot more under 10A discharge. Its initial capacity is the highet of the holy trinity GA MJ1 35E but after 20 cycles it becomes the worst.

You want to use hBN or cubic ? problem with encapsulation is that you will put thermomechanical stress on the components and end up with a failed charger in few months. Better solution would be a sealed aluminium enclosure filled with oil at 90% (to accomodate thermal expansion in the...

Samsung 30Q for excellent high-rate performance during the whole life of the cell Panasonic 18650BM for excellent cycle life, safety, overall performance and value (Tesla cell) Sanyo GA for best initial performance but heavy internal resistance degradation over time

If the cell suffered from overheating (probably not the case here), Hydrogen Fluoride may have been formed by thermal degradation of the LiPF6 electrolyte. So I would recommend you to NEVER smell battery gas, since HF is lethal at ppm levels. Though in your case it's probably just CO2 and...