There are times when one's build goes off on a tangent to satisfy some overwhelming urge or to make supposedly better use of circumstances and opportunities, or just for a change.
I had been looking at some
hang-onto-for-a-sunny-day discarded lithium ion laptop battery packs for a year or two. My plan was to break them open and see whether they would be any real use for powering any of the electrics in the build. I ended up with 9 x 18650 cells, 2200mAh capacity, LG and Panasonic cells that weren't damaged during the battery pack wrecking. They charged without drama in an appropriate charger. It took a while as the charger only accommodates 2 cells at a time.
I discovered the Vruzend (based in USA) 18650 Battery Pack Kit consisting of interlocking top and bottom caps with spring contacts, connecting strips and screws - no welding or soldering needed. An order was placed with their Australian outlet, Aussie Outdoor Gear, along with a Banggood order for 4 x 20A 18650 BMS controller boards, and an 8 x USB outlet buck/boost voltage regulator modules.
The battery kit arrived within a couple of days, yesterday, which was great service but I will have to wait longer for the Banggood stuff.
I needed to test the suitability of the used cells that I had on hand. The purpose of all this is to provide a nominal 12V battery, expandable to beyond 9Ah. Using nine 18650 cells that were retrieved from two discarded laptop battery packs, it took only a short while to make up 3 x 3S battery banks. At the original 2200mAh capacity of the cells, this was three 2200mAh units with a nominal voltage range of 9V (specification sheet minimum) to 12.6V (specification sheet maximum). The three sets of three cells were then connected in parallel with each other, thereby providing a complete battery pack representing a new cell value of 6600mAh (6Ah) at the previously mentioned voltage range.
As the potential performance of the used cell pack was unknown, it was put on test with the running lights of my Warrior trike. The test ran for
8.25hrs before being aborted as it was not going to be possible to monitor the end time as I would be asleep when it happened. At the time the test was stopped, the running lights were still performing the same as they were at the start and the battery voltage was sitting at approximately 11.1V, the specification sheet nominal voltage and exceeding my expectations. The current draw during the test was a nominal 110mA.
A very successful test and I have resumed the test from where I left off yesterday.
A way of customising your own battery pack and re-purposing used cells in the process. You can use new cells instead, of course.