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?

[vadim_t]

No, you shouldn't with any kind of modern battery.

Li-Ion doesn't like full discharges, and in fact the internal circuitry should make it impossible. Lead-acid will very quickly become unusable if left fully discharged. And for battery packs, full discharge risks cell reversal, which causes damage.

The only case where you should still do that is when there is some sort of internal statistics being kept of how long the battery is estimated to last, which is out of sync with the actual battery.

That's not for any sort of cleaning though. It's just for fixing incorrect estimations of remaining battery time, which causes devices to turn off too soon, or have them fail to shut down nicely before the battery runs out.

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.

Yes, better, not different

[dutchwhizzman]

It just shows how much of the last bar you still have. Once you go from one bar to zero, you essentially only know you have "less than one bar" left, but not how much. There is no change to how deep the batteries get discharged, you just know better what risk you are taking if you decide to drive on. The TFA also tells about the software "hack" to the 120V charge cable to make it work with 240V as well. That's not so special, considering the same cable is used with different software in Europe, where 240V is the standard. Also improving it to be better, but not different.

Re:Why is it "american"?

[vlm]

I'm a bit tired of people claiming that an activity is very american just because the person is from USA and likes it.

You must be the life of the party when an american brings up the topic of "american football" (as opposed to real football = soccer). I'm from the US, our style of football is somewhat popular here (only around 5% really care, but at least 50% go along to get along with them). So our style of football is very american, oh well.

The reason for "american DIY culture" is our profoundly anti-business anti-entrepreneur climate. If you own a set of wrenches in Ecuador even if you mostly work on your own vehicles you'll be considered a "pro car mechanic" by an American if you ever help your neighbor change their windshield wiper blades, so an Equadorian (?) in that situation can't be DIY if they're a businessman, so there is no DIY culture in Equador, even if the same percentage of guys are turning wrenches under a shade tree in their backyard... In the US we have a huge quantity of laws and regulations to prevent individual entrepreneurs from competing with the bigger businesses, because those bigger businesses have purchase the govt and "suggested" those laws to the purchased politicians to improve their profits. I can't even begin to imagine the paperwork and financial resources required to let me change my neighbor's oil for a couple bucks... but I can change my own (so far) without too much govt interference, although they're working on it...

An american DIYer is pretty much just a frustrated entrepreneur. In a better country they're be a very small part time businessman, a dude with a "side job".

Re:Empty Never Means Empty

[vlm]

Gas powered cars still go many miles after the gas gauge hits empty. A fuel gauge reading empty is suppose to tell you "Fill up as soon as possible" not tell you need to get out and push.

Empty means buy a new fuel pump because the old one just sucked up all the water, rust, sand, whatever from the bottom of the tank. Also the in-tank pumps are notorious for overheating and burning out in air/vapor and only running cool when immersed in fuel, so even a perfectly clean tank can burn out the pump if the pump is in an empty tank. Maybe more so in summer than winter... Also if the pump fails after pumping rusty water for awhile rather than instantly, you'll probably end up replacing the fuel filter, maybe the injectors, who knows.