App note: Implementing a practical off-line Lithium-Ion charger using the UCC3809 primary side controller and the UCC3956 battery charger controller

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 […]

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 […]

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 […]

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 […]

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 […]