App note from Texas Instruments about Li-Ion battery charger design. Link here (PDF) A primary goal in the design of any portable electronic device is to make the product as small and lightweight as possible. When the device is powered by a rechargeable battery, a means of charging the battery from the AC line must […]
Tag Archives: charger
Building a 12V DC MagSafe charger
Steve blogged about his 12V DC MagSafe charger built: Now that I have a solar-powered 12V battery, how can I charge my laptop from it? An inverter would seem absurdly inefficient, converting from 12V DC to 110V AC just so I can connect my Apple charger and convert back to DC. It would work, but […]
Counterfeit Macbook charger teardown: convincing outside but dangerous inside
Ken Shirriff writes, “What’s inside a counterfeit Macbook charger? After my Macbook charger teardown, a reader sent me a charger he suspected was counterfeit. From the outside, this charger is almost a perfect match for an Apple charger, but disassembling the charger shows that it is very different on the inside. It has a much […]
A 3.6V LiFePO4 charger for under 50c
Nerd Ralph built his own 3.6V LiFePO4 charger: I like LiFePO4 batteries. They have a rather flat discharge at around 3.2V, which is ideal for powering 3.3V devices without a regulator. You can also use them in devices that take 2 standard AA cells by using a blank shunt in the 2nd battery slot since 2 […]
Cheap USB LiPo charger notes
Jim writes: Since I use a variety of cells, I wanted to be able to charge at Chip2014under 1A. Most such charge controllers have a single resistor that programs the bulk charge current, so I looked for the datasheet to find what values I’d need for the charge currents I wanted. The chip is marked […]
BT-C3100 intelligent battery charger teardown
Alan Parekh of Hacked Gadgets writes: Thanks to GearBest for sending in this Opus BT-C3100 V2.0 Intelligent Battery Charger for review. at a quick glance this charger might look like any other charger that you see at the grocery store. Your generic store bought brand probably also has 4 charging bays for AA and AAA batteries, it probably has 2 […]
A 5c lithium ion battery charger
Nerd Ralph writes: As various sites explain, lithium-ion rechargeable batteries should be charged to 4.2 volts. USB ports provide 5V, so all I needed was a way to drop 5V down to 4.2 or less. Standard diodes have a voltage drop of 0.6 to 1.0 volts, so I pulled up the datasheet for a 1n4148, […]
Simple 6x USB charger with current monitor
Frank Zhao shared his simple 6x USB charger with current monitor in the project log forum: This is a simple 6 port USB device charger with a individual current monitor on each port. The charging current is indicated using RGB LEDs. Blue means slow charge (under 250mA), green means 250mA to 750mA, red means over 750mA, and purple […]
FT230X charger detection investigation
Baoshi writes: I bought some FT230X (FT230XS) USB-USART bridge chip recently for a new design. FT230X is not only cheaper than the traditional FT232RL, but also offers a new fancy “USB charger detection” function. This interests me because I’m quickly running out of desk space and power socket. I wish the new device to be […]
Power charger and supply regulator
Asgard shared his BLiVIT project in the forum: One of the things I have noticed missing, for a pretty long time, is a good *safe* lithium cell charger that also supplies a load with a good efficient regulator. My answer, I hope is the BLiVIT. This is a moderate-sized board that incorporates charging from either […]
NiMH trickle charger with status indication
NiMH trickle charger with status indication: In spite of the considerable media attention to the concept of recyclable power sources, usage of rechargeable Nickel-Metal Hydride (NiMH) cells has been limited. The combined charger and cell cost have been a mitigating factor in favour of primary cells. The high internal impedances of primary cells are not […]
555 based constant current lead-acid battery charger
Kennith needed a 1A constant current lead-acid battery charger for his HAM radios. He augmented the 555 contest winning battery charger circuit by replacing the relay with an LM317 in constant current mode. Since the SLAs are relatively small, and I only need them charged between radio outings, I opted to build a 1A constant […]
App note: Battery/charger load switch approximates ideal diode
Portable devices require a circuit that switches the power supply between battery and charger. This is usually done by using a diode on the battery line – when the charger is plugged in, the diode is reversely polarized and disconnects the battery from the rest of the circuit. This method however has drawbacks, namely power […]
App note: Inductive and capacitive Li-ion cell balancing methods.
No two lithium ion battery cells can ever be the same. There are variations in state of charge, capacity, impedance, and temperature characteristics. These slight differences lead to cells being disproportionately charged or discharged when they are connected in series. This shortens battery life, and even total breakdown of cells is possible. To solve these […]
LiPo auto-balancing circuit
ScottD tipped us to the LiPo Auto Balancer circuit featured in the Elektor magazine’s June 2010 issue. When using multiple lithium ion/polymer batteries in series an auto-balancing circuit is needed to make sure all the cells charge equally. Due to slight differences in capacity, some cells will reach full charge before others. This effect increases […]
The basics of USB battery charging: a survival guide
An introduction to USB battery charging: a survival guide Arguably the most useful part of USB’s power capabilities is the ability to charge batteries in portable devices, but there is more to battery charging than picking a power source, USB or otherwise. This is particularly true for Li+ batteries, where improper charging can not only […]