Gary12345 wrote:I will charge to 4.1v and then discharge to 3v. The Yuasa spec sheets show that they test between 2.75-4.1v but there is very little below 3v. That should give me a good idea if the cells are usable in a car.
Curious to know whether you have received your block of 8 cells yet and if so whether you have had time to test their Ah capacity ? I'm still toying with the idea of replacing four of my cells. Two are quite bad - both high internal resistance and significantly lower capacity than most of the others, a 3rd is nearly as bad capacity wise but resistance seems OK, and a 4th is not far behind the three worst ones. There's then a significant gap to the next worst cell with most of the remaining 84 cells being relatively closely grouped so probably not worth replacing any of the others.
I removed, fixed and replaced my battery pack on the drive without a hoist - its fairly involved but its definitely doable - I had the car up on 3 concrete blocks (the 4" thick ones) under the wheels so the whole car was 12" up, removed the big orange fuse then the thick orange cables, then bolted trolley wheels on a wooden pallet, put this under the car, used 2 trolley jacks with 2x4" on top jacked up underneath the front and back of the pack, then undid the pack bolts and electrical connectors and carefully lowered the jacks with the wood and battery pack on top down onto the wooden pallet, then slid the battery pack out.
I've been following along and helping with the diagnosis in this thread where a CMU is being replaced:https://www.speakev.com/threads/c-zero- ... ir.137750/
He has tried two different approaches - both which seem doable to me. The first was to raise the car up high on ramps and stands and then use a hand operated hydraulic pallet mover to lower the pack down and withdraw it from the car. So as long as you can hire one for a weekend this seems like one way to do it, although lining everything up when raising it up again could be fiddly.
Later in the thread he came up with a second method where four of the main mounting bolts are replaced with very long threaded rods with a spacer tube and nut such that once fitted you remove all the other bolts and simply unwind the nuts to lower it down onto a small trolley.
Slower than the hyraulic lift, but very minimal resources required, and in theory it should make getting the battery back up into exact alignment easier as it will be getting lifted up on the threaded rods into perfect alignment. I could definitely see myself able to use this approach so I'm now considering again whether I should do a cell swap to prolong the useful life of the car.
My Ah capacity is down to 34.0Ah now and still falling relatively rapidly, DC rapid charging speeds are much slower than two years ago (due to the two high resistance cells reaching peak voltage too soon) and I believe that were it not for the 4 bad cells the capacity would still be up around 38Ah now.