lorenfb wrote:"measuring resistance" ?????????????dwl wrote: Can anyone confirm how accurately it might be measuring resistance
The Leaf Spy manual says: “Hx The meaning of this number is not fully understood but it appears to be inversely related to the battery internal resistance. As the internal resistance of the battery pack increases it is thought this percentage decreases. As internal resistance increases more energy is lost within the pack and the pack heats up more under load.”
I am asking how well the Hx measure is tracking resistance and to avoid confusion I should have added “noting it is represented as an inverse ratio (conductance or susceptance)”. Sorry I didn’t add that. I am not suggesting it is a direct measure and never considered it has units of Ohms or even Siemens.
With the new values of 115 appearing for the 40kWh it is possible this has not been scaled and this pack has 15% less resistance than the 30kWh. However, it seems to me unlikely the 30kWh was the same as the 24kWh when new.
From the other thread:
Roddzilla wrote:After update:
AHr = 65.30
SOH = 82.16
Hx = 58.34
ODO = 35,815
1 capacity bar gone (2 were recovered by the update!)
What we are seeing is low Hx on the 30kWh and if this is representing the change of resistance as a linear measure (e.g. 100/58.34=1.7x more resistance than new) it is a lot. For a car that has been restored to 82% SoH with the update there are valid concerns about the “health” of the battery.
Some help from battery scientists may be needed. I understood by the time the resistance had risen to 2 to 2.5x when new it was starting to get into the later stages of Lithium plating but this may be wrong. Hopefully Hx isn’t a linear measure and resistance hasn’t risen that much. Any other insights welcomed.