[schiffern]

I would be amazed if Tesla Motors was running that pack at 90% depth of discharge. 80% is far more typical.

The other thing to consider is that as the voltage drops, so does the leakage current.

Really, this whole thing could be solved by putting a tiny solar panel on the back dash.

[rrrazdan]

Which is what the Nissan Leaf does(pretty nifty idea, I'd say). But its not really a solution in the sense that it wouldn't work for cars parked inside.

[schiffern]

If it's parked inside, generally either A) you have a plug, or B) it's artificially lit 24/7. That should be enough to compensate for leakage current.