Alan Parekh @ hackedgadgets.com writes:
This video was going to be a repair of this Portable USB Charger but as it turns out there wasn’t anything electrically wrong with it. It didn’t work out of the box but I think that must have been caused by some oxidation on the USB contacts. It seems to work like a champ now. The control chip for the DC/DC converter looks to be this DHMF chip. I have never seen the swoop logo before and can’t seem to find any data on this 5 pin device though. It is probably similar to the LT1302 (PDF) that the Adafruit MintyBoost uses. The efficiency of this circuit doesn’t appear to be as efficient as a proper one built using the LT1302 though since when drawing 500mA from the output it can maintain very close to 5 volts out (2.5 watts) but needs an input of 3 volt at 1.3 amps to do it (3.9 watts). This gives us an efficiency of about 64%, the graph from the datasheet of the LT1302 indicates that it could perform at about 86% under these conditions.
Portable USB Charger Teardown - [Link]
1,6V rechargeable batteries experience “rebirth” and bring several advantages in comparison to 1,2V NiCd accumulators
Experts in electrotechnics might say, that these are a long-time known batteries invented already by Edison thus being no novelty at all. That´s true but in contrast to older tyes is in technological advance of electrolyte and electrodes so as to reach a substantially higher lifetime that few decades ago.
So what´s interesting about these rechargeable batteries? By one sentence, NiZn cell has an output voltage of approx. 1.65V, what´s about 0.4V more than NiMH/ NiCd cells.
At the same time they´re able to provide a high current, similarly like NiCd/ NiMH cells, that´s why they´re also usable in devices with high current demands (conductivity of Zinc is about 15% than Cd). NiZn cells are easily recyclable and they´re very environmentally friendly. Another benefits:
- energy density of NiZn cells is about a third higher than that of NiCd cells (Wh/kg and also Wh/liter).
- higher voltage (1,6-1,8V) enables to reach a higher voltage of „battery-packs“ with a lower count of cells
- lifetime is comparable with NiCd cells
- no memory effect, trouble-free recharge to 100%
- flat discharging characteristics, average voltage aprox. 1,6-1,7V
It is recommended to recharge NiZn cells by C/4 to 1C current (i.e. for example 500 mA to 2000 mA for a 2000mAh cell) while observing a max. voltage of 1.9V/ cell. It´s not recommended to leave cells at a so called “trickle charging” as overcharging might decrease lifetime of cells. Naturally, like in case of almost all rechargeable batteries, the highest lifetime can be reached at operation on a partial discharge (not to a deep discharge). It´s worth to say, that NiZn are not an ideal replacement into devices with a very small power consumption ( e-g- remote controllers), where still win primary alkaline cells.
In our offer can be found NiZn cells themselves: 4AA2500mWh1.6V BP4 and 4AAA900mWh1.6V BP4 as well as a set – charger + cells (4xAA+4xAAA) NizN Charger + Accu. This charger charges by 500 mA current (AA/AAA) and monitors each slot individually. During recharging a LED at agiven slot blinks slowly (1x/s) and after finishing of recharge it shines continuously. In case of a faulty cell it blinks quickly (4x/s).
NiZn rechargeable batteries – when Nickel and Zinc create a strong pair - [Link]
Tutorial – MicroLipo and MiniLipo Battery Chargers @ The Adafruit Learning System.
Sooner or later you’ll need to cut the cord…the power cord! Untether your electronic project from the tyranny of the wall adapter and take it out into the world. That’s where batteries come in, and you may have been seduced by the high power density, large current capabilites and recharge-ability of Lithium Polymer or Lithium Ion batteries. These battery chemistries have quickly become the most popular rechargeable batteries in consumer products, powering everything from keychain mp3 players to huge laptops.
Tutorial – MicroLipo and MiniLipo Battery Chargers - [Link]
7-42VDC Input 5V 2A USB Output Power Supply. Compatible with Raspberry Pi, Arduino, iDevices, Mobile Phones and other USB Devices.
Having to use a Raspberry Pi and other USB Devices in an electronics production environment where 5V isn’t standard, I have noticed a lack of power supplies capable of fitting in. A unit had to be designed to fit into systems where 12V & 24V are the norm or where batteries / solar panels etc are the only supply method available.
7-42VDC to USB Supply/Charger - [Link]
by Ken Shirriff:
Disassembling Apple’s diminutive inch-cube iPhone charger reveals a technologically advanced flyback switching power supply that goes beyond the typical charger. It simply takes AC input (anything between 100 and 240 volts) and produce 5 watts of smooth 5 volt power, but the circuit to do this is surprisingly complex and innovative.
Apple iPhone charger teardown - [Link]
By Tahar Allag, Wenjia Liu:
Cell phones are a good example of how functionality and performance have both increased significantly in portable devices over the last few decades. They have become more complex and can do many basic tasks as well as any computer. The extra functionality that has transitioned the smartphone from a phone-call-only device to a multipurpose portable device, which makes it more power hungry than ever before.
The internal battery pack is the main source of storing and delivering power to portable-device circuitry. Batterycharger ICs are responsible for charging the battery pack safely and efficiently. They must also control the power delivery to the system to maintain normal operation while plugged in to wall power. The battery pack is required to store a large amount of energy and be charged in a short amount of time without sacrificing weight and volume. The increased charge and discharge currents, as well as the smaller physical size, make the packs vulnerable to physical and thermal stresses. Therefore, battery chargers are no longer required to perform just as a simple standalone charger
AppNote: Battery charging considerations for high-power portabledevices - [Link]
Designers of rechargeable battery-powered equipment want a charger that minimizes charge time with maximum charge current by maximizing the power taken from the supply without collapsing the supply. Resistances between the supply and the battery present a challenge. This article explains how to design the charging circuit to achieve the maximum power from the adapter despite the undesired resistances between the supply and battery.
AppNote: Extract maximum power from the supply when charging a battery - [Link]
One, tiny Dart. Power for all your devices. Perfect for your mobile lifestyle.
The Dart is the world’s smallest, lightest laptop adapter. At a powerful 65W it is a perfect complement to today’s thin, lightweight, portable laptops. It fits in a pocket and is designed with a USB port and single outlet profile to make it easy for you to stay charged up when you’re on the road. We hope you are as excited about the Dart as we are and looking forward to finally carrying just one, tiny Dart to charge all your electronics. Join our campaign and never be stuck powerless again!
Dart: The World’s Smallest Laptop Adapter - [Link]
In December 2013 Linear Technology announced a new chip – LT8490. This chip includes a 80V Buck-Boost Lead Acid & Lithium Battery Charging Controller that actively finds true Maximum Power Point in solar applications.
No yet available, that chip looks very promising. It operates with input voltages down to 6V and can boost that to charge batteries with higher voltage. I made already a schematic and board design from the preliminary datasheet that charges a 3S LiPo from a solar panel with up to 5A. A small board size allows usage in model gliders with large wing span to charge the battery in flight.
Solar charger with MPPT - [Link]
Compact battery chargers require overcurrent protection and temperature monitoring to ensure safety. These chargers also need to fit into small form factors, and generally have a lot of pressure to also be very inexpensive, but only have to provide a simple charging ability.
Furthermore, compact packaging is required to integrate the battery charger into a system. Renesas has 8/16-bit microcontrollers available in compact packages with as few as 10 pins, making them ideal for these applications.
78K0/Kx2: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit and on-chip oscillator; low power consumption,30 to 80 pins.
78K0/Kx2-L: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit, on-chip oscillator, and operational amplifier; ultra-low power consumption, 16 to 48 pins
78K0S/Kx1+: 8-bit All Flash microcontroller: wealth of on-chip peripheral functions such as a reset circuit and on-chip oscillator; 10 to 30 pins
R8C Family: Timer, 5 V operation, and Small Package
P-ch MOSFET: Low on-resistance, compact low-profile
Renesas Battery Charger Solutions - [Link]