Informal testing of battery storage, soliciting feedback on testing

terjee

Enlightened
Joined
Jul 24, 2016
Messages
729
Location
Bergen, Norway
Hi guys!

I've got 24x VTC5A, with no current plans for them. They're basically my "in case they become hard to get"-stash.

In the meantime, I'm planning on doing some informal testing with them, just to gather some empirical data on self discharge and so on, and this is where you guys are free to jump in if you'd like. I do have a test-plan, but if you see any room for improvement, or anything you'd like me to do different, it's much more useful to jump in now, rather than when testing is well underway, or even completed.

Currently the plan is to split them into two sets, charge one to 4.2V, and the other to 3.92V. The reasoning being one set "fully charged", and the other set charged to a useable degree, but with a lower SoC/voltage, to avoid any voltage related stress during storage.

Then immediately drain one battery from each set:
- Immediately
- After 1 month
- After 2 months total
- After 3 months total
- And onwards with one pair every 3 months

I'm thinking draining using 0.5A down until 3V (open to suggestions, perhaps 3.3V or 2.7V?)

The goal of the whole thing being to get some data about recoverable energy after long term storage, getting data for questions like "How big a difference is there for a cell that sits for a year, after having been charged to either 4.2V or 3.92V?", and so on.

After discharging, I'll probably cycle the cells a few times to measure capacity. I'm also curious about things such as if there'll be any significant difference is capacity of cells fully charged vs. 3.92V, after having rested for a year.

Unless there's a reason to terminate testing early (too much self discharge?), then the full test-run would be about 3 years, so I'd rather hear about any suggestions or requests now, rather than having to restart half way through. :p
 
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