An Obsessively Thorough Battery (and More) Showdown

September 5, 2014 by Marsh 17 Comments

There are a number of resources scattered across the Internet that provide detailed breakdowns of common products, such as batteries, but we haven’t seen anything quite as impressive as this site. It’s an overwhelming presentation of data that addresses batteries of all types, including 18650’s (and others close in size), 26650’s, and more chargers than you can shake a LiPo at. It’s an amazing site with pictures of the product both assembled and disassembled, graphs for charge and discharge rates, comparisons for different chemistries, and even some thermal images to illustrate how the chargers deal with heat dissipation.

Check out the review for the SysMax Intellicharger i4 to see a typical example. If you make it to the bottom of that novel-length repository of information, you’ll see that each entry includes a link to the methodology used for testing these chargers.

But wait, there’s more! You can also find equally thorough reviews of flashlights, USB chargers, LED drivers, and a few miscellaneous overviews of the equipment used for these tests.

[Thanks TM]

Controlling A Hot Plate’s Temperature For The Lab

September 5, 2014 by Matt Terndrup 8 Comments

When you need precise heating — like for the acetone polishing shown above — the control hardware is everything. Buying a commercial, programmable, controller unit can cost a pretty penny. Instead of purchasing one, try creating one from scratch like [BrittLiv] did.

[BrittLiv] is a Chemical and Biological Engineer who wanted something that performs well enough to be relied upon as a lab tool. Her design utilizes a plain, old hot plate and with some temperature feedback to run custom temperature ramps from programs stored on an SD card.

The system she developed was dealing directly with temperatures up to 338°F. The heating element is driven from mains, using an SSR for control but there is also a mechanical switch in there if you need to manually kill the element for some reason. An ATmega328 monitors the heating process via an MAX6675 thermocouple interface board. This control circuitry is powered from a transformer and bridge rectifier inside the case (but populated on a different circuit board).

She didn’t stop after getting the circuit working. The project includes a nice case and user interface that will have visitors to your lab oohing and aahing.

The Reason Dead Batteries Bounce

September 5, 2014 by Brian Benchoff 23 Comments

For the last few years, very well-informed people have been able to tell if an alkaline battery is good or not simply by dropping them. When dropped from an inch or two above a hard surface, a good battery won’t bounce, and will sometimes land standing up. A dead battery, on the other hand, will bounce. Thanks to [Lee] and a few of his friends, we now know why this happens.

While hanging out with a few of his buddies, [Lee] was able to condense all the arguments on why dead batteries bounce to two theories. The first theory, the ‘bounce theory’ said dead batteries had an increase in outgassing in the battery, increasing the pressure in the battery, which increases the spring constant of the battery itself. The second theory, the ‘anti-bounce theory’, said the gel-like properties of the electrolyte worked as a sort of mass damper.

[Lee] designed an experiment to test the outgassing ‘bounce theory’ of bouncing batteries. Instead of dropping a battery, an object – in this case a brass slug – was dropped onto both good and bad batteries. There was no difference. Even after holes were drilled to vent any gasses inside the battery, the brass slug bounced off both good and bad batteries the same way.

This means the reason dead alkaline batteries bounce is due to the electrolyte. [Lee] cut open a few AA cells and found the electrolyte in a good battery was a mushy mess of chemicals. In the dead battery, this same electrolyte hardened into a solid mass. [Lee] compares this to an anti-bounce hammer.

Finally, more than a year after most of us learned about bouncing dead batteries thanks to [Dave Jones]’ video, we have an answer. It’s a chemical change in the electrolyte that turns it from a goo to a solid that makes dead batteries bounce.

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Celebrate Hackaday’s 10th Anniversary: October 4th In Pasadena

September 5, 2014 by Mike Szczys 11 Comments

We’ve had a bit of fun today with a post about our 10th Anniversary, now here’s the real deal.

If you happen to be in the Los Angeles area on Saturday, October 4th you should join us to help commemorate 10 years of happy hacking. The day-long event comes in many pieces. We’ve put together workshops, a mini-conference, a day-long build, and we’ll cap it all off with a party.

Hackaday is a global community though. If you can’t be there in person you should set the day aside to do some hacking in your lair, or maybe even get the Hackaday readers in your area together and see what comes of it!

Without further ado, here’s what we have planned:

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Hacklet 14 – Hacks Around The House

September 5, 2014 by Adam Fabio 25 Comments

In this weeks Hacklet we’re looking at household hacks. Not necessarily globally connected home automation hacks, but task specific hacks that we want in our lives yesterday!

We’ve all had it happen, you’re burning the midnight oil on a project when you realize it’s garbage night. The mad dash to collect empty anti-static bags, last night’s Chinese food, and the rest of the trash before actually venturing outside in the dark.

[Mehmet-cileli] doesn’t have to deal with any of that, thanks to My Bins, his automated trash and recycling can moving system. Normally the bins are stationed near the house. Each garbage night, the system springs into action. The cans and their platform pivots 90 degrees. The entire system then rolls along a track to the curb. Once the cans have been collected, everything rolls back ready for more trash. We just hope [Mehmet’s] garbage men are nice enough to put the bins back on their platform!

Next we have the perfect cup of tea. [Marcel] kept forgetting his tea while it was steeping. After ending up with ink a few times, he built this Automatic Tea Timer. A button starts the timer, and after a few minutes, the tea bag is automatically lifted and a light illuminates to let you know your tea is ready. [Marcel] used a ~~Raspberry Pi~~ ~~Arduino~~ ~~555~~ simple R-C timer circuit to create his delay. The lift arm is a discarded hard drive read arm. The light bulb limits current through the voice coils.

[Juan Sandu] always has veggies with his Smart Small Greenhouse. [Juan] has created a desktop sized greenhouse that gives plants what they crave. No, not Brawndo, we’re talking water, warmth, and light. An Arduino Uno uses sensors to monitor humidity, temperature, light, and moisture. Based upon one of two pre-set plant types, the system determines when to water, turn on lights, or even power up a fan to keep temperatures plant friendly. [Juan] is still working on his greenhouse, but his code is already up on Github.

Next up is [nerwal] with his entry in The Hackaday Prize, GrillUp. GrillUp is a remote grill temperature monitoring system with a cooling spray. Up to 6 food grade thermometers provide GrillUp with its temperature data. If things are getting a bit too hot, Grillup cools the situation down by spraying water, beer, or your favorite marinade. The system is controlled over Bluetooth Low Energy from an android smart phone. A laser pointer helps to aim the water spray. Once the cooling zones are set up, the system runs automatically. It even has a sprinkler mode, where it sprays everything down.

Every hacker’s house needs some Sci-fi mood lights, right? [spetku and maehem] round out this weeks Hacklet with their Fifth Element Stone Mood Lighting. Originally an entry in the Hackaday Sci-fi contest, these mood lights are based on the elemental stones in everyone’s favorite Bruce Willis movie. The lights are 3D printed in sections which stack over foamboard cores. The actual light comes from a trio of RGB LEDs. LED control is from the same brain board which controls the team’s Robot Army. The lights are designed to open up just like the ones in the movie, though fire, earth, wind, and water are not required. The servos [spetku and maehem] selected weren’t quite up to the task, but they mention this will be remedied in a future revision.

That’s a wrap for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Unlock On LAN Apartment Security

September 5, 2014 by James Hobson 29 Comments

Here’s a cool little variation of that handy little function called Wake on LAN — [Jonathan] found himself locked out of his apartment one too many times, so he decided to add his own fail safe backup in order to get inside without a key — using a Raspberry Pi of course.

His apartment is one of those older style ones where the door is always locked and you use a buzzer to let someone in (or a key to get in yourself). This made it super easy to add some internet connectivity to the system. [Jonathan] tapped into the buzzer with a relay since the system uses medium voltage AC to operate. A Raspberry Pi triggers a transistor using its GPIO to click the relay on and off, effectively controlling the lock.

Using a WiFi dongle he’s connected the Pi to his home network and written a simple perl script to trigger the relay — all he has to do is visit a URL on his phone or computer and the door will unlock instantly!

Once the system worked [Jonathan] soldered all the components onto a breadboard and hooked it up. He still needs an enclosure for it, but it’s been working well since he installed it.

Another option would be to use an RFID tag system through the door, which could be pretty cool as well.

Radioshack Phone Dialer – Red Box

September 5, 2014 by Hackaday 58 Comments

i thought i’d start out with this hack while we’re in beta, since it was one of the first ones that really got me interested in the way phones worked and how many consumer electronics can be used for new and educational things. a “red box” was a device that would simulate coins being dropped in to a pay-phone, hence free phone calls for many people until the phone systems changed. the most popular device to modify was a radioshack tone dialer, a simple solder of a 6.5536 mhz crystal was all it took and you could “drop” 5, 10 and 25 cents at a time to make calls.

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