Keeping the LiPo Smoke Where It Belongs

Nothing brings joy to a hacker’s heart like taking a cheap gizmo and making it useful. Over at [AndyHull] popped open some cheap LiPo battery power packs to see if he could power a Canon Powershot camera. The entire shebang would be left in the wilderness for photography so keeping it inexpensive was a big goal since it might be destroyed or lost.

The power packs [Andy] looked at have a TP4221 controlling the charge cycle for up to four 18650 LiPo cells connected in parallel. The controller also boosts the voltage to 5 volts for one or two USB ports while providing automatic shutdown if the LiPo cell voltage drops below 3.2v. Below that voltage the cells can be damaged and might possibly cause a fire.

The packs [Andy] used also had a torch output to drive an LED almost directly from the cells. That output is a nominally 3.8 V at 100 mA which is just what he needed to power the Canon Powershot. It could be used to power small micros or other low power devices.

The LED was removed and replaced by a connection to outside the pack. The torch output is triggered by two quick presses on a switch that was also replaced with a connector to allow remote control.

If you’re looking for powerful battery options, give LiPo a try and have a look at [Andy]’s LiPo battery safety issues post, also on For a broader LiPo overview, see this obsessive rundown of various batteries.





An Obsessively Thorough Battery (and more) Showdown

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]

Hackaday Links: February 1, 2012

The only thing he needs now is a micro and RTC

For [Dino]’s 44th Hack A Week extravaganza, he made powered window blinds in five minutes. It’s a simple build with a small gear motor and a bit of tubing to adapt the shaft to the control rod of the blinds. Good job [Dino].


The wonderful [Lizzie] over at LUSTlab realized that typing meta keys really slows down the development process. The result? Foot pedals for the Shift and Command keys. No build log for this one, but it’s just a set of old racing pedals and a disused keyboard.

So much cooler than a potato

[mdevaev] out of Russia built a fully articulated GLaDOS replica. Here’s the build album and the relevant MLP forum post. This GLaDOS is tiny – probably less than a foot long, but it moves around and speaks (Russian, which is weird). Somebody get us a couple of motorcycle fenders so we can build the 1:1 scale version.

Visualizing a plane of fog

[greg] was looking for a way to visualize the chaotic turbulence of air. He mounted a laser on a computer fan and held some dry ice above the beam. The result looks like it could make for an interesting photography project, but check out the video if you don’t believe us.

We were asking for it

We asked for battery charging circuits that don’t use specialized parts. [Petr] found this one that only uses few transistors, a MOSFET and a voltage regulator. In one of the Hackaday comments, [atomsoft] had the idea of putting a USB plug on the traces to save a bit in component costs. [mohonri] said he designed one, but we have yet to see it. Perhaps next links post…

LiPo charging circuit tutorial

As far as battery technology goes, Lithium Polymer cells are the bee’s knees. They’re powerful enough to handle very demanding applications and come in a multitude of sizes for any conceivable application. There’s a problem with LiPos, though – they have the tendency to explode when charged incorrectly. Luckily, [Paul] sent in a great tutorial on building a LiPo charger that works over USB.

In the original design of [Paul]’s board, he chose a Maxim MAX1551 Lithium battery charger. Confounded by the expense and/or unavailability of this IC (although Sparkfun has a few), he moved onto the similar Microchip MCP7813. This IC supports charging from a power source from 3.5 to 6 Volts as would be found in a USB hub.

The board [Paul] came up with is incredibly small – just barely larger than the USB plug itself. The layout is fairly simple as well. We’re thinking this could be a highly useful application of some home board fabrication. If you have a simpler way to charge LiPos that don’t require a specialized chip, send it into the tip line.