Called BH to find out if they've done a random IR test on any of the 33G cells? As far as he knew they've never tested
any for Internal Resistance. He said that an IR in the 30s (milliohms) is still ok for those 2020 33G cells.
If i understood him correctly BH has sold 30,000 of 50,000 with no performance complaints ... which i second as no complaint about performance (capacity). My use is moderate cruising pulling
on average no more than 10 amps from 10s3p DIY battery. So, at only $2/cell it was a good deal as all 30 cells are as normal as normal can be :wink: (IMO).
After a few cycles (so far) the mV variance of the 10 parallel groups is no more than 4mV. Whether at the bottom discharge of 34.0V (bounce back voltage) or top charge of 41.0V the variance between the 10 p-groups is no more than 4mV. So, no need to bottom balance the 10 parallel groups before bulk charging to 4.10V (41.0V as 10s3p).
My 33G cells' label code is: 3 KM3T. Thought 'K' meant a manufacture date in 2019 ... could be wrong. With moderate cruising use and bottom balancing (when necessary) this 10s3p DIY battery configuration should provide a cycle life that justifies paying $2 ea for these Samsung 33G cells ...
https://batteryhookup.com/products/30-100-new-samsung-inr18650-33g-3150mah-18650-cells
Granted this DIY Vruzend build isn't the most efficient configuration. My DIY reasoning for a less than ideal current flow was for experimental purpose. Currently the IR (milliohms) from 1s-5s is: 14, 15, 14, 16, 19 and from 6s-10s is: 14, 15, 15, 18, 21. Used my RC Balance Charger for measuring IR of p-groups as 5s3p (1s-5s & 6s-10s), and as 5s6p.
IR as 5s6p using Y cables as shown in attached photo is: 7, 9, 8, 10, 13 (milliohms). The RC Balance Charger used to measure IR isn't the most accurate, but at least it gives me a sort of benchmark (to go by) as the cells age with more and more c/d cycles: 50, 100, 150, 200 (hopefully). I don't use a BMS - keep a close eye on it all the time ... :thumb:
DISCONNECT TOP WIRES IF CHARGING AS 5S6P AND FOR MEASURING RC BALANCE CHARGER IR FUNCTION (or )