If we want to obtain a 5V voltage from only 2 NiMH batteries, we´ll face the fact, that the most of common DC/DC circuits doesn´t operate at such a low voltage. LT1304 controller belongs among circuits, which handle this situation without problems and it also provides several extra things.
To obtain 3.3 or 5V from a lower voltage is a typical requirement at battery-powered or portable devices. Naturally, to obtain 5V it is also possible to use 4-5 NiMH cells or 2 Li-Po cells, but then the device is uselessly bigger, heavier and more expensive. The solution is just the usage of a suitable step-up circuit. LT1304 from Linear Technology belongs to “MicroPower” DC/DC step-up circuits operating already from a very small voltage, 1.5V typically.
Thanks to a very low power consumption (10uA/Shutdown) and a built-in independent low battery detector, it is optimized for usage with batteries. LT1304 needs for its operation only a few external components – 2 capacitors, 1 inductor and 1 diode is all that is necessary to create an operating DC/DC circuit.
LT1304 is available in 3 versions – LT1304VCS8-5, LT1304CS8-3,3 with fixed voltages and LT1304CS8 with adjustable output. Versions with fixed output voltages don´t need a divider in a feedback, what further simplifies a circuit.
John Donovan writes:
Alternative energy sources deliver small amounts of power intermittently, and at times power levels may not match the needs of the applications that depend on them. Some form of energy storage is needed, though the solution will vary with the demands of the application. This article will examine various energy buffering solutions, including small form-factor batteries, thin-film batteries, and supercapacitors, highlighting both their specifications and the applications to which they are best suited.
Storage Alternatives for Energy Harvesting Applications - [Link]
With the new Accucell Alpha 100 and Alpha 200 chargers you will manage it easily and moreover you don´t have to care about the type of batteries you´ll put in.
RAM batteries (rechargeable alkaline manganese) have already gained many fans, as they are environmentally friendly, have an ideal voltage of cca 1.5V and feature a very low self-discharge. They are mainly suitable for devices with a low to mid power consumption. To maintain their good properties for a long time, it is only necessary to avoid a deep discharge under 0.9V, very high discharging and charging currents and mainly to observe charging characteristics with a current limitation and a maximum voltage of 1.65V/ cell.
New microprocessor controlled chargers Alpha 100 and Alpha 200 control every channel separately, that´s why it is possible to charge any number of batteries from 1 to 4 pcs. They are designed to observe an optimum course of charging for RAM accumulators. This is also reflected in the charging current of 155-195mA x4 (AA) and 70-100mA x4 (AAA) respectively. Charging of common RAM cells lasts approx. 2-12 hours, depending on their capacity and a level of discharge.
New chargers provide one extra bonus – they are also able to charge NiMH and NiCd cells, because they are able to recognize the type (chemistry) of an inserted battery (from a voltage curve at charging), adapting a charging course accordingly.
Charge the environmentally friendly RAM batteries - [Link]
Double layer electrolytic capacitors already enable to replace backup batteries in many applications.
Modern high-capacity double layer capacitors (also known as supercapacitors) feature a very high energy/volume ratio, compared to usual electrolytic capacitors. Their capacity is so high, that they are able to replace backup batteries in many designs. On the market there are available miniature types as well as physically big types with capacities of tens to hundreds of Farads.
One of the biggest advantages of capacitors in comparison to batteries is their long lifetime, because their electrodes don´t undergo degradation neither after many thousands of cycles. On the other side, even modern batteries have a limited lifetime and a limited number of cycles, because energy storage in batteries is related to chemical changes of electrodes during charge/discharge (change from a solid to a liquid form, crystallization,…), what causes degradation of electrodes.
In our offer, you can find small “coin-type” double layer capacitors suitable for backup power supply of memories. For example a capacitor with a 1F (1000mF=1 000 000 uF) capacity charged at 5V can store energy of 12.5 Jouls (E=1/2*C*U2), what is 12.5 Wattseconds. This energy is in most cases sufficient to ensure a safe backup of memories at a voltage dropout. Such energy is also sufficient for a short time power supply of low power devices. This can be very useful for example for a safe write of data to EEPROM and a safe switch off of a device.
Supercapacitors instead of batteries? - [Link]
Are you looking for a portable breadboard power supply with a selectable voltage? Also thinking about how long the batteries will last? This project utilizes one or two AA/AAA batteries to generate a preselected voltage of 5V or 3.3V, and squeezes the batteries untill they have almost no power at all. AASaver is based on the Microchip MCP1640 boost converter. [via]
When your electronic devices report that the batteries are ‘dead’ and need to be replaced, do you ever feel frustrated that there is often still a lot of juice in them? Don’t throw away the batteries yet! You can use the remaining energy to do a lot of things, such as powering LED flashlights. This is possible by using a boost converter, which can bump the low battery voltage to a higher voltage, enough to light up LEDs or even power breadboard circuits.
Squeeze the power out of batteries using AASaver - [Link]
This is an app note from Maxim describing how to protect your Lithium Ion batteries from reverse insertion into the charger. The circuit is a Li-Ion battery charger with an added analog comparator designed to detect when then battery is inserted the wrong way and disconnect it from the charger. [via]
Combining a linear-mode single-cell lithium-ion battery charger (MAX1551) with a comparator (MAX9001) and n-channel FET adds a layer of reverse-battery protection that protects a single cell lithium-ion battery charger and battery from damage due to backwards insertion
Protect your batteries from reverse insertion - [Link]
If you often work with batteries and SMT transistors, then the new UT132B multimeter is the right choice for you.
Into our offer we incorporated the new UT132B multimeter – a “brother” of the UT132D, type, which we have introduced to you recently. UT132B provides practically the same functions, including possibility to measure hfe of SMT transistors , NPN and PNP types in a SOT-23 package, by means of a special adapter. The difference between these two instruments is, that UT132B features measuring of 1.5V and 9V batteries status. That´s why it is ideal for everyone, who needs to simply and quickly judge status of batteries. Measuring of 1.5V batteries is proceeded at a 15 Ohms load and measuring of 9V batteries at a 1 kOhm load. The instrument has a HOLD function and a main switch, thus it is not necessary to turn a measuring ranges switch to switch off the device. Similarly like UT132D, also UT132B is very reliably and comfortably held in a hand thanks to compact dimensions and an ergonomic shape.
The new UNI-T multimeter even for testing of batteries - [Link]
New technology improves both energy capacity and charge rate in rechargeable batteries.
EVANSTON, Ill. — Imagine a cellphone battery that stayed charged for more than a week and recharged in just 15 minutes. That dream battery could be closer to reality thanks to Northwestern University research.
A team of engineers has created an electrode for lithium-ion batteries — rechargeable batteries such as those found in cellphones and iPods — that allows the batteries to hold a charge up to 10 times greater than current technology. Batteries with the new electrode also can charge 10 times faster than current batteries.
The researchers combined two chemical engineering approaches to address two major battery limitations — energy capacity and charge rate — in one fell swoop. In addition to better batteries for cellphones and iPods, the technology could pave the way for more efficient, smaller batteries for electric cars.
The technology could be seen in the marketplace in the next three to five years, the researchers said.
A paper describing the research is published by the journal Advanced Energy Materials.
“We have found a way to extend a new lithium-ion battery’s charge life by 10 times,” said Harold H. Kung, lead author of the paper. “Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today.”
New technology improves both energy capacity and charge rate in rechargeable batteries - [Link]
KIT (Karlsruhe Institute of Technology) researchers have developed a new concept for rechargeable batteries. Based on a fluoride shuttle — the transfer of fluoride anions between the electrodes – it promises to enhance the storage capacity reached by lithium-ion batteries by several factors. Operational safety is also increased, as it can be done without lithium. The fluoride-ion battery is presented for the first time in the “Journal of Materials Chemistry” by Dr. Maximilian Fichtner and Dr. Munnangi Anji Reddy.
Lithium-ion batteries are applied widely, but their storage capacity is limited. In the future, battery systems of enhanced energy density will be needed for mobile applications in particular. Such batteries can store more energy at reduced weight. For this reason, KIT researchers are also conducting research into alternative systems. A completely new concept for secondary batteries based on metal fluorides was developed at the KIT Institute of Nanotechnology (INT). [via]
Fluoride increases storage capacity of rechargeable batteries - [Link]
Fun with a few 9V batteries. (244 of them) @ The Custom Geek… [via]
So I needed a break from working on a project again, and I remembered that I had a bunch of 9V batteries and thought, ‘I wonder if that would be enough voltage to hold an arc?‘. The answer is yes, it would. So I made a little video of melting some alligator clips and crispifying some LED’s, a CD, and a cap. Or at least trying to blow up the cap, that was one tough cookie..
I used 244 9V batteries, that were not new, but not dead. When you do the math, this should be 2,196 Volts, but that is when they are new. I measured (in blocks) 2,000 volts total. Lots of sparky..
Fun with a few 9V batteries. (244 of them) - [Link]