Best charging strategy?

[donald]

There are phase changes in the electrodes as the cell voltage passes 4V/cell so it is still appropriate to charge to less if you can.

Are these phase changes in the lattice structure of the material (just asking out of curiosity...I worked with a crystallography group in college)?

That is what I understand. Lithium is not chemically bonded to the carbon electrode, but 'fills' it by a process of intercalation. This is a bit like how carbon filters work (sort of!). So whenever you charge a Li battery, the carbon electrode physically swells slightly, and eventually it needs to re-order slightly to take on the final %age of Li it can. You're really pushing Li into the electrode in the last few stages, and if you overdo it you'll begin to plate the electrode in metallic Li, but that happens over 4.2V whereas these automotive cells are pushed to 4.1V to keep them below that point. (Commercial cells are less important, so they tend to get charged to the full 4.2V).

Ultimately, a battery with a very short life will most likely arise because one or two cells start going bad, due to thermal ageing. Is there any way to replace just the bad cells if you're able to identify them?

The cells are mounted in modules. You can replace individual modules. Originally, Nissan were implying this would be almost a routine maintenance operation, but the problem with this is that the module has to be balanced with the other modules in the pack because they are in series.

You also have to worry about resealing the pack, reconnecting the BMS, etc, etc. Better this is done in a dedicated re-manufacturing centre.

I can imagine that what will happen is rather than offering to replace modules they will replace the whole packs, and then cannibalise the 'good' modules from all the returns, and then re-match them into 'new' second grade packs (which is probably what you'll get under the $5k replacement programme). It makes more sense to do it this way.

 

[dgpcolorado]

I can imagine that what will happen is rather than offering to replace modules they will replace the whole packs, and then cannibalise the 'good' modules from all the returns, and then re-match them into 'new' second grade packs (which is probably what you'll get under the $5k replacement programme). It makes more sense to do it this way.

The LEAF battery packs seem to degrade pretty evenly from all reports I've seen here. Reports of failed modules are very rare. Since we have instrumentation that monitors the voltage of the 96 cell-pairs, it is very easy to spot ones that fail.

Those who purchase of replacement battery packs will get a new 2015 "lizard" battery pack, complete with a new 60 month/60k mile capacity warranty. They aren't rebuilt or anything like that. So far free replacements done under the capacity warranty have all been new packs as well, although that isn't specified in the warranty.

 

[dgpcolorado]

The one I use, Leaf DD, is no longer made but they do pop up as resales from time to time; it is one of the easiest and most convenient to use...

For example, here's a Leaf DD up for sale:
leaf DD for sale

I don't expect it to last long.