Alan B
100 GW
eTrike said:+1 Fechter, this is why Luna's claim of 14Ah@20A, etc. are nothing but smoke and mirrors.
Alan, solid info ofc, but I think you missed that the 46V is OCV taken after the cells have cut off and had time to bounce back. He ought to be actually hitting 38V LVC accordingly.
is spot on in describing the recent sudden loss he mentioned at 11.x Ah. Thanks for describing that in detail."The already weak cell group is being repeatedly rammed to LVC, which is likely to cause further reduction in capacity."
I would not expect a bounce back that deep, and we don't have data to support that. Taking a voltage reading immediately at cutoff via the charging connector would be very useful to help understand what is going on. Individual cell group voltages would really be useful, if we could get those.
The data supports a deteriorating pack scenario, with increasingly reduced capacity, which is not the behavior of a healthy 4P GA cell pack (irrespective of any particular claims or expectations about pack capacity). Deterioration would most likely be a single cell group rather than the whole pack synchronously behaving this way.
It is true at higher currents that the capacity is reduced, but one of the reasons we like lithium is that it suffers from this effect very little with the varying loads of ebike use, which don't draw peak currents all the time. I often see essentially full (low current rated) capacity from a pack in ebike use, so I don't expect that is the issue here with these high quality cells. It also doesn't fit with the rapidly declining capacity data. It could be something like a marginal weld on one cell, or physical damage to one cell, or even just a problem with the BMS (which is actually more likely than a bad cell), the cells may be just fine, but an increasing imbalance could cause these results and a broken BMS may be unable to restore balance.