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An Interview With Tesla Battery Hacker [wk057]

November 11, 2014 by 63 Comments

We covered [wk057] and his Tesla Model S battery teardown back in September. Since then we had some time to catch up with him, and ask a few questions.

You’ve mentioned that you have a (non hacked) Tesla Model S. What do you think of the car?

It’s the best car I’ve ever driven or owned, period. Not to get too into it, but, I love it. I’ve put almost 20,000 miles on it already in under a year and I have no real complaints. Software feature requests… but no complaints. After almost a year, multiple 1700-miles-in-a-weekend trips, and an overall great experience… I can never go back to a gas vehicle after this. It would be like going back to horses and buggies.

A salvage Tesla Lithium battery had to be expensive compared to a Lead Acid setup. What made you go with the Tesla?

Actually, if you consider that the Model S battery is already pre-setup as a high-capacity pack, contains the wiring to do so, and the modules are much more energy and power dense than any lead acid battery bank, it’s actually almost cheaper than a comparable lead acid bank and all the trimmings.

I haven’t officially weighed them, but the modules from the Model S battery are roughly 80 lbs. 80 lbs for a 5.3 kWh battery is around 15 lbs per kWh, which is impressive. For comparison, a decent lead acid battery will have a little over 1 kWh (of low-rate discharge capacity) and weigh almost the same.

Also, the Tesla pack is much more powerful than a lead acid bank of the same capacity.
Generally a lead acid battery bank would have a capacity that would only be realized with slow discharges, so, 1/20C. Much over that and you sacrifice capacity for power. 1/20C for an 85kWh pack is only 4.25kW, barely enough for a central air unit and some lights without losing capacity.

Now the Tesla pack can be discharged (based on how it does so in the vehicle) at up to 3.75C for short periods, and at 1/2C continuously without really affecting the overall capacity of the pack. That means I can run 10x more power than lead acid without a loss in overall charge capacity. Leads to a much more flexible battery solution since the loads will, in reality, always be so low that this will not even come into play with the Tesla pack, but would almost always be a factor with lead acid.

Charging is also somewhat better with the Tesla battery. Charge a lead acid battery at a 1/2C and it will boil. Charge the Tesla pack at 1/2C (42kW) and it might warm up a few degrees. Oh, and the charging losses at high rates are much less than lead acid also.
Overall, without continuing to yack about the technical aspects, it’s just a much better battery, takes up less space, weighs less, and has more power available.

There are likely decent arguments for other solutions, but the rest aside, this one won out because it was definitely more interesting.

Click past the break to read the rest of our interview with [wk057]!

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Hackaday Prize Finalist: A Network Of Satellite Ground Stations

November 7, 2014 by 29 Comments

There are astonishing things you can do with a network of sensors spread across the globe, all connected to the Internet. Thousands of people have already installed hardware to detect lightning and flightaware gives out subscriptions to their premium service to anyone who will listen in to airplane transponders and send data back to their servers. The folks behind SatNOGS, one of the five finalists for The Hackaday Prize are using this same crowdsourced data collection for something that is literally out of this world: listening to the ever-increasing number of amateur satellites orbiting the planet.

There are dozens of cubesats and other amateur satellites flying every year, and they have become an extremely popular way of experimenting in a space environment, giving some budding engineers an awesome project in school, and testing out some technologies that are just too weird for national space agencies. The problem with sending one of these birds up is getting the data back down; a satellite will pass above the horizon of a single location only a few times a day, and even then for only minutes at a time. The SatNOGS team hopes to change that by planting receivers all around the globe, connecting them to the Internet, and hopefully providing real-time telemetry from dozens of orbiting satellites.

[Pierros] from the SatNOGS team was kind enough to sit down and answer a few questions for us about his entry to The Hackaday Prize. That’s below, right after their finalist video. Some of the SatNOGS team will also be at our Munich event where we announce the winner of the Prize.

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Hackaday Prize Finalist: A Portable SDR

November 5, 2014 by 74 Comments

No other project to make it to The Hackaday Prize has people throwing money at their computer screen hoping something would happen than [Michael Colton]’s PortableSDR. It’s a software defined radio designed for coverage up to 30MHz. Amateur radio operators across the world are interested in this project, going so far as to call this the first Baofeng UV-5R killer. That’s extremely high praise.

[Michael] was kind enough to sit down and answer a few questions about how his entry to The Hackaday Prize has gone. You can check that out below, along with the final round video of the project. Anyone who wants their own PortableSDR could really help [Michael] out by taking this survey.

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Developed On Hackaday: Crowd- Funding Campaign Start!

November 4, 2014 by 47 Comments

For a little less than a year open source enthusiasts from all over the globe got together to work on an open source offline password keeper. We narrated our progress here on Hackaday and always asked our readers’ opinion when critical decisions were to be made.

Today, the wait is finally over: the Mooltipass crowdfunding campaign finally arrived.

In some of our Developed on Hackaday series posts we noticed that it was tricky for us to convey the benefits of the device we were developing. The first 3 minutes of our video therefore explain good security practices and how the Mooltipass can help users with their credentials security. For our readers that may not have followed our adventure since its beginning, the campaign’s text will provide them with a simple (yet detailed) explanation of what the Mooltipass can do. Finally, our geeky readers will find at the end of our write-up a few links supporting our claims. We would have liked offering cheaper pledges but we unfortunately need to hire professional javascript developers to finish our app & extension.

Our Mooltipass Developed on Hackaday series therefore come to an end. We would like to thank you for your support and hope that you enjoyed seeing an idea materialize into a crowdfunding-ready product!