It looks like I never posted the final parts of this story. I've got some back-tracking to do - let's go back to mid September 2023...
I got the 3rd pack apart and tested. More of a mixed bag in that pack but there were plenty of strong-looking sticks and I was more confident I could make a good pack with what I had. What I did was ranked all 60 sticks by resting charged voltage and by voltage drop under load. The sticks that clearly had a dead or dying cell in them were disregarded. That left me with a list of sticks from strongest to weakest. The bulk of the stronger sticks were from the original Insight pack and the crossover point with the others meant I discarded 6 sticks from the Insight pack and used 6 stronger ones from the third pack.
What I did next I think was the clever bit. The system monitoring in the car looks at
pairs of sticks, not individual sticks. So if it sees a
pair that are out of whack it cuts the assist/regen or flags a fault. Using a combination of the resting voltages and voltage drops, I matched up pairs so that the stick
pairs all showed very similar resting voltages and voltage drops under load. Before I could make the pack back up, I had to re-charge one of the sticks I’d fully discharged during testing. I borrowed a bench supply from work, set the current control to 0.5A and put it on a mechanical timer overnight (in the socket):
Bit hokey, but it worked a treat and nothing exploded overnight. That also meant nobody got hurt and nobody died, so I was good to go.
It took a spectacularly long time to build the pack back up because I had to do it on the kitchen table and I got a lot of help from little interested hands. Screws and tools kept moving and interested little faces keep getting in the way and adding useful random things like flowers, spoons and herbs and spices. It was frustrating, but at the same time I secretly wanted my kids to be involved, so I couldn't get too angry at them
With the pack assembled it was ready to put in the car. As I said above, I chose to swap the best six sticks from the second HCH pack (aka pack 3) with the weakest six sticks from the original Insight pack. That seemed to be where the crossover point was in terms of stick performance once I'd ranked all 60 of them. Then I put them all in order of voltage drop under load and paired them up one from each end of the list until I got to the middle. The logic here is the car monitors them in pairs, so I want the pair voltages to match as closely as I can get them. Then it was just a matter of double check I got the stick pairs in the right places in the pack based on the connections on the board in the back of the pack which links the sticks together.
Pack went in with no issues, then it was a matter of giving it a quick top-up charge overnight and it was ready for a test drive the next day. This was October 14th, so I was a bit up against it before the insurance and tax ran out at the end of the month:
And that was that, after a test drive I called it fixed. It was immediately obvious that the battery was performing properly. It was actually working the best I think I’d ever seen it. No issues on a 10 mile test drive with a few deliberate restarts thrown in the mix. Motorway work was fine and it was healthily dipping in and out of the battery on acceleration and deceleration. I got a clear stretch on a local bypass where I could nail it for a good 15 seconds before I had to smash the brakes and it was happy putting out the full 100A of assist for all of that. It was also using full regen on hard braking which it won’t always do if the battery is out of whack. I was VERY happy/relieved/drained
All that was left to do was to clean it up because it was absolutely caked in crud from the last 3-odd months of neglect:
[January 2024 checking in: yeah, uh, I'm not very good at cleaning cars so that bit hasn't actually happened yet]
October 21st I used it for one last trip to the tip to make some space in the house. Bye bye knackered microwave, dead hifi, old hoover, two Civic hybrid battery cases and some old clothes. Hello rusty old French bike. Er, What? That wasn’t supposed to happen
October 26th I put it in for a last-minute MOT just before putting it on SORN. Pass with no advisories, as usual. I think that’s seven in a row since it’s been in my hands that it’s passed without even a single advisory!
And that brings us up to date. It's currently sitting on my drive waiting for me to give it a good wash and wax so I can put it up for sale.