Lost & Found... Headway cells

[flagman1776]

I have 16 Headway cells on the bench... unused old stock... stuck in orange blocks but not wired or connected to anything. They were "lost", not charged or maintained at all, unfortunately. Most have 3.3V or so. One has self discharged to 1.2 or something. One reads 0.1 (so that's junk.)
I'm going to have to put stickers on... start testing... Any thoughts?

The TravelScoot pack I was going to assemble is only 8S. I have also recovered the bits I was going to use to assemble the pack(s). I hit some stumbling block... don't remember just what.

I've been getting by quite nicely with the reworked / repaired pack of generic China cells so I didn't "need" the Headway pack... but I realized the patch work could fail at any time... & leave me without power. I expected I'd need to swap packs on long outtings but with hour & a half Hyperion charging... it was never an issue.

[Burgerman]

Most have 3.3V or so.

Those will be fine.

The rest had a higher self discharge level, and went below 2v over time and so are now junk. Charge the good ones individually. Then take out 30% in Ah to store.

[flagman1776]

I spoke too soon. I took all the cells out of the building blocks & went through testing & marking. I have 9 good cells. 7 cells below 2 V. Instead of 2 sets of 8 S... I have one.

I have all the bits to assemble the harnesses. I should have kept on & assembled them. I think... can't really recall... but there was one or more issue(s) with the physical mounting and assembly. Then the project got lost. Entirely my fault.

[Burgerman]

The problem. LiFe cells all tend to self discharge quite slowly. But do so at different rates. Everything else is very consistent between cells. But self discharge rates does vary.

Its the main reason lithium packs get out of balance over time. Charging them, re balances them up to 100% again. Its why when building a big pack its best to charge all full. Leave in a box for a month. Then recharge each one individually and make a note of the mA returned. It wont be much! It means you can add these mA together and make parallel groups that add up to the same level. It doesn't mean that a pack will not go dead over a long period. But it means it should do so all at the same time and so stay in balance well between charges. I suggest a refresh/balance charge every 2 to 3 months. And then remove 30% to store.

[flagman1776]

I notice a strange results. 2 sets of 8 cells.

"The Spare cells": One set laid flat in the orange blocks... 6 of 8 still good. All hardware in a baggie.

"The Mock Up": One set of 8, mostly assembled in series with buss bars & machine screws (no wires at all). There were 2 not connected, though in place... iffy contact. 3 of 8 still good.
**The balance wires shown in the earlier photos of the mock up had been removed & were not in place**

Both sets were on top of each other, not shorted by "bench stuff".

The series mounted set did much less well than the spare cells group. I want to learn as much as possible from this expensive mistake.

[Burgerman]

I think unrelated.