Hacking the Nissan Leaf EV

An anonymous reader writes "The New York Times is running a story on people hacking the Nissan Leaf electric vehicle. 'Using Mr. Giddings’s home-brewed E.V. fuel-level display, Leaf drivers get the confidence to extend their driving range by 10 percent or more. His gauge, which displays the actual state of charge, reveals that the Leaf dashboard’s "zero bars" display comes on when the battery pack has several miles remaining.' Here's an interesting quote from one of the hackers, Phil Sadow, who was interviewed for the story: 'I don't like the term hacking because it's been portrayed by the media as something evil. To me, hacking is actually very American. Go out to the garage. Take it apart. Make it better.'"

Comments

Better you say?

[BiggerIsBetter]

Perhaps Nissan knows something about their batteries and BMS that he doesn't, and the false zero reading is there to ensure the batteries last as long as they're intended to? Last I heard, you weren't supposed to completely discharge lithium batteries if you wanted to ensure a usefully long service life.

Re:Better you say?

[queazocotal]

Taking cells all the way to 'zero' in a battery is generally a bad plan, it both stresses the cells more - discharging them at high currents at the very end of the discharge is harsh on them, causes extra wear due to deeper cycle life, and risks overdischarging weaker cells in the battery.

Re:Better you say?

[jtownatpunk.net]

It's also probably intended to keep people from running out of juice on the freeway or some other place where it would be dangerous to be unable to move the vehicle. Honestly, if you're down to the last few miles, it's time to recharge.

Re:Better you say?

[Zocalo]

I too keep hearing conflicting advice on this, but as far as I can tell the underlying truth is what is indicated in the parent's post.

I'm looking at a Canon LP-E4 battery (from a 1 series EOS camera) and it definitely says "Li-ion" on it, and I also have the manual for the camera with me. These are quite intelligent batteries, with very accurate charge remaining indictors, etc. Every now and then they indicate the need for a "calibration charge" to ensure accurate battery life indication, and to quote the manual on the process "After the calibration is completed and the battery is totally drained, it will take a further two hours to recharge the battery fully." At a guess, I get this maybe warning once per year, per battery - and perhaps even less frequently than that.

I've come across this kind of thing on other "high-end" Li-Ion batteries too, including on laptops, a high-end GPS unit and a satellite comms system. I've never seen this kind of thing on cheaper clones, in lower-end devices like phones, or in any other gadgets where the battery might be regarded as disposable once it deteriorates. Unless the battery in question has a means of asking for a calibration charge, or some such, and a charger that has a dedicated mode for doing so, then you should always try and recharge the battery before it fully drains.

Re:Better you say?

[Aqualung812]

It's simple economics;

No, it isn't so simple. There are many examples of expensive devices requiring many more manual steps because it gives the perception of value. "Mine requires more work because it is such a precision device" seems to be a very common thing.
Sometimes, this is a good thing, because it allows for better control by the end user *IF* they know what they're doing. SLR vs point & shoot, for example.
Other times, it is simply a status thing. For example, I have a solar powered watch that is synced to the atomic clock in Colorado every morning. My watch will always be within 0.5 seconds of actual time. However, a Rolex that costs thousands more doesn't include the solar charging or atomic clock sync will never be as accurate as my watch, and requires more effort. Still, a Rolex has the perception of higher value.