A Post-Mortem For An Electric Car Charger

August 7, 2019 by Tom Nardi 46 Comments

[Mastro Gippo] recently purchased a wall mounted charger for his electric car that looked great and had all the bells and whistles he wanted. There was only one problem: the thing burned up on him. Looking to find out how this seemingly high-end piece of hardware gave up the ghost so easily, he took it apart and tried to figure out where things went wrong. While he’s not looking to sling any mud and actually name the company who produced the charger, he certainly has some choice words for whoever green-lit this particular design.

With the charger open, there’s little doubt that something became very toasty inside. A large swath of the PCB has a black char mark on it, and in some places it looks like the board burned right through. After a close examination, [Mastro] is of the opinion that the board heated up to the point that the solder actually liquified on some connections. This conductive flow then shorted out components below it, and things went from bad to worse.

But where did all the heat come from? [Mastro] was stunned to see that a number of the components inside the charger were only rated for 30 amps, despite the label for the product clearly stating it’s good for up to 32A. With components pushed past their limits, something had to give. He wonders how such a device could have made it through the certification process; an excellent question we’d love to know the answer to.

The worst part is, it looks like the designers might have even known there was an overheating issue. [Mastro] notes that there are heatsinks bolted not to a component as you might assume, but directly to the PCB itself. We’ve seen what happens when designers take a cavalier attitude towards overheating components, and the fact that something like an electric vehicle charger was designed so poorly is quite concerning.

Putting Some Smarts Into An Electric Car Charger

April 27, 2019 by Tom Nardi 22 Comments

Many electric cars feature a timer capability that allows the owner to set which hours they want the vehicle to start pulling a charge. This lets the thrifty EV owner take advantage of the fact that the cost of electricity generally goes down late at night when the demand is lower. The Renault Zoe that [Ryan Walmsley] owns has this feature, but not only does it cost him extra to have it enabled, it’s kind of a hassle to use. So being an enterprising hacker, he decided to implement his own timer in the charger itself.

Now controlling high voltages with a lowly microcontroller might sound dangerous, but it’s actually not nearly as tricky as you might think. The charger and the vehicle actually communicate with low-voltage signals to determine things like the charge rate, so it turns out you don’t need to cut into the AC side of things at all. You just need to intercept the control signals between the two devices and modify them accordingly.

Or do you? As [Ryan] eventually realized, he didn’t need to bother learning how the control signals actually worked since he wasn’t trying to do anything tricky like set the charge rate. He just wanted to be able to stop and start the charging according to what time it was. So all he had to do was put the control signal from his car through a relay controlled by a Particle Photon, allowing him to selectively block communication.

The charger also had an optional key lock, which essentially turns the controller off when the contacts are shorted. [Ryan] put a relay on that as well so he could be absolutely sure the charger cuts the juice at the appropriate time. Then it was just a matter of getting the schedule configured with IFTTT. He mentions the system could even be tweaked to automatically control the charger based on the instantaneous cost of electricity provided by the utility company, rather than assuming overnight is always the most economical.

We’ve seen a fair amount of electric car hacking, but with only a few exceptions, the projects always steer clear of modifying the actual chargers themselves. In general hackers feel a lot safer playing around in the world of DC, but as [Ryan] has shown, safely hacking your EV charger is possible if you do your homework.

Implementing Qi Inductive Charging Yourself

April 11, 2019 by Jenny List 21 Comments

Inductive charging is a technology that has promised a lot, but hasn’t quite delivered on the promise of never needing to plug in your phone again. The technology behind it is surprisingly simple though, and [Vinod.S] takes us through it all with an ATtiny13-based example.

An inductive charger has to be clever in its operation, for if it were to operate continuously it would soon have more in common with an inductive hob and thus become a fire risk, so it has to be sure that a compatible device is resting upon it before it tries to transmit power. It achieves this by periodically sending out a pulse of power intended to wake any devices in contact with it, and the device responds with a serial data stream encoded onto the device’s field by modifying the resonance of the receiver tuned circuit. This is done by a pair of MOSFETs under the control of the ATtiny in [Vinod]’s device, resulting in a functioning inductive power receiver built on a piece of prototyping board and sporting a buck converter capable of supplying 5 volts suitable to charge a phone. You can find the code on GitHub and see it in action below the break.

This tech has made an appearance here before a few times, such as when a Qi charger was integrated into a Chromebook.

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Cheaply Charging Cylindrical Cells

February 19, 2019 by Brian Benchoff 15 Comments

For one reason or another, a lot of us have a bunch of 18650 cells sitting around. Whether they’re for flashlights, our fancy new vape pen, remote controlled toys, or something more obscure, there is a need to charge a bunch of lithium ion cells all at once. This project, by [Daren Schwenke], is the way to do it. It’ll charge ten 18650 cells quickly using a stock ATX power supply and less than twenty bucks in Amazon Prime parts.

The idea began when [Daren] realized his desktop lithium ion charger took between 4-6 hours to fully charge two 18650 cells. With a Mountainboard project, or a big ‘ol electric skateboard waiting in the wings, [Daren] realized there had to be a better solution to charging a bunch of 18650 cells. There is, and it’s those twenty bucks at Amazon and a few 3D printed parts.

The relevant parts are just a ten-pack of 18650 cell holders (with PC pins) and a ten-pack of 5V, 1A charging modules (non-referral Amazon link, support truly independent journalism) meant to be the brains of a small USB power bank. These parts were wired up to the 5V rail of a discarded ATX power supply (free, because you can scavenge these anywhere, and everything was wrapped up with a neat little 3D printed mount.

Is this the safest way to charge lithium ion cells? No, because you can build a similar project with bailing wire. There is no reverse polarity protection, and if there’s one thing you never want to do, it’s reverse the polarity. This is, however, a very effective and very cheap solution to charging a bunch of batteries. It does what it says it’ll do, nothing more.

Tiny Solar Energy Module (TSEM) Brings Big Performance

August 12, 2018 by Donald Papp 16 Comments

The Tiny Solar Energy Module (TSEM) by [Jasper Sikken] is not only physically tiny at one-inch square, but it is all about gathering tiny amounts of solar energy — amounts too small to be useful in a conventional sense — and getting meaningful work done, like charging a battery for later use. Elements that make this board easy to integrate into other projects include castellated vias, 1.8 V and 3.3 V regulated outputs that are active when the connected battery has a useful charge, and a low battery warning that informs the user of impending shutdown when the battery runs low. The two surface-mount solar cells included on the tiny board are capable of harvesting even indoor light, but the board also has connection points for using larger external solar cells if needed.

The board shows excellent workmanship and thoughtful features; it was one of the twenty Power Harvesting Challenge finalists chosen to head to the final round of The Hackaday Prize. The Hackaday Prize is still underway, with the Human-Computer Interface Challenge running until August 27th. That will be followed by the Musical Instrument Challenge before the finals spin up. If you haven’t started yet, there’s still time to make your mark. All you need is a documented idea, so start your entry today.

Ultra-Low Power, Energy Harvesting Battery Charger

July 8, 2018 by Donald Papp 10 Comments

This half-inch square ultra-low power energy harvesting LiPo cell charger by [Kris Winer] uses a low voltage solar panel to top up a small lithium-polymer cell, which together can be used as the sole power source for projects. It’s handy enough that [Kris] uses them for his own projects and offers them for sale to fellow hackers. It’s also his entry into the Power Harvesting Challenge of the Hackaday Prize.

The board is essentially a breakout board for the Texas Instrument BQ25504, configured to charge and maintain a single lithium-polymer cell. The BQ25504 is an integrated part that takes care of most of the heavy lifting and has nifty features like battery health monitoring and undervoltage protection. [Kris] has been using the board along with a small 2.2 Volt solar panel and a 150 mAh LiPo cell to power another project of his: the SensorTile environmental data logger.

It’s a practical and useful way to test things; he says that an average of 6 hours of direct sunlight daily is just enough to keep the 1.8 mA SensorTile running indefinitely. These are small amounts of power, to be sure, but it’s free and self-sustaining which is just what a remote sensing unit needs.

Charging An Electric Supercar With Lemons, Kids, And The Sun

June 29, 2018 by Dan Maloney 27 Comments

First things first: the tease on this video, that an electric supercar can be charged from a massive lemon battery array, is exactly that – a tease. Despite that, it makes for an interesting story and a great attempt to get kids exposed to science and engineering.

The story goes that [Mark] was approached by Volkswagen to help charge the batteries on their entry for the upcoming Pikes Peak International Hill Climb, the annual “Race to the Clouds” in Colorado. Racers are tortured by a 4,700′ (1,440 m) vertical climb over a 12.42 mile (20 km) course that features 156 switchback turns. Volkswagen’s entry is an electric supercar, and they sent [Mark] a portable battery cart to charge up the best way he saw fit.

Teaming up with [William Osman], the first attempt was a massive array of lemon cells, made with waterjet-cut strips of zinc and copper held in a plywood frame. Studded with 1,232 lemons, the battery performed just about as well as you’d expect it would. Plan B was cute, and another of [Mark]’s attempts to pad his “Funnest Uncle Ever” score a bit. He devised a zip line with regenerative braking to charge a cordless drill battery, and then indirectly harvested the energy in the battery by turning it into lemonade for a bunch of kids. The sugared-up kids rode the zip line till the battery was charged.

That was still a drop in the bucket, though, so Plan C saw [Mark] install a large solar array on his roof; the tie-in here was that the lemon-powered kids got to design a cleaning system for the solar array. A weak link, to be sure, but the kids had fun, and we can’t deny that the car will at least be partially lemon-powered when it heads up the hill.

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