Battery warranty

Battery warranty

Not sure if this is covered elsewhere already.

Is the warranty on the larger batteries better because the current is drained from more battery cells in parallel and the individual cells are therefore not stressed as much for the same total current?

Is this also the reason why the 0 - 60 mph acceleration is (artificially) lower for the smaller batteries?


Timo | October 12, 2012

Warranty is better for that reason, and for the reason that you don't need to charge as often. Charge cycle is main reason to what causes battery degradation, and with 85kWh battery you need to recharge it half as often as 40kWh battery.

Acceleration is also reduced with smaller batteries because of low power density of high energy density batteries.

DouglasR | October 12, 2012


You don't need to charge as often if you are on a trip, but for day-to-day around town use, wouldn't you charge just as often? TM recommends plugging in each night, not like the older battery technologies that favored deeply discharging the battery before recharging. So wouldn't the larger battery result in the same number of charge cycles, just not running the battery down to as low a level?

pilotSteve | October 12, 2012

@Timo - interesting speculation: are you thinking that perhaps only some thesub-sections ("blocks") of series cells are charged when not going for a full (range) charge?

Or something like this for "load balancing" to spread the charge/discharge cycles in a smart way?

I believe there are many patents (some unpublished or not yet issued) that relate to these kind of fundamental engineering issues that will keep Tesla light years ahead of other manufacturers new to the BEV party.

Maybe this technology and patent portfolio is a key part of the reason that Daimler and Toyota chose to license power systems from Tesla?

Teoatawki | October 12, 2012

A charge cycle consists of drawing down and replacing the equivalent of a full charge, regardless of how much is used on any given occasion. So, a 25 mile daily commute (rt) would take 10 days to equal 1 charge cycle.

Timo | October 13, 2012

"charge cycle" is from full to empty to back to full -equal amount of charging. If you only top off the battery every day it equals only part of the cycle.

@pilotSteve, all batteries are charged equally.
@DouglasR, It is not "how often", it's "what percentage" for daily charging. Also slower current charging/discharging is more gentle to batteries, so it is double-benefit for larger batteries given same charge power and same driving habits. Not that this has big impact though (unless you go to limits of the batteries).

I admit the "don't need to charge as often" is a bit misleading into first sentence and didn't quite mean what I tried to say, but taken literally it is true too.

Brian H | October 13, 2012

"didn't quite mean what I tried to say" is very good. Have to 'member that one!

mrspaghetti | October 13, 2012

Timo for President!

cerjor | October 14, 2012

Teoatawki: I just read that the new electric Smart car does not use the Tesla drivetrain.

Teoatawki | October 14, 2012

I didn't think it would use a Tesla drivetrain.