Charging Lithium ion batteries at slow rates

When the charge rate during the constant current phase is low, the charger process will spend less time during the constant voltage tail. If you charge below about 0.18 C, the cell is virtually full when the 4.2 volts is reached. This can be used as an alternative charge algorithm. Just charge below 0.18C constant current and terminate the charge when the voltage reaches 4.2 volts per cell.

Safety

Every lithium ion battery pack should have a method of keeping the cell balanced and preventing them from being over-discharged. This is usually done with a safety board which monitors the charge and discharge of the pack, and prevents dangerous things from happening. The specifications of these safety boards are dictated by the cell manufacture, and may include the following:
Reverse polarity protection
Charge temperature--must not be charged when temperature is lower than 0° C or above 45° C.
Charge current must not be too high, typically below 0.7 C.
Discharge current protection to prevent damage due to short circuits.
Charge voltage--a permanent fuse opens if too much voltage is applied to the battery terminals
Overcharge protection--stops charge when voltage per cell rises above 4.30 volts.
Overdischarge protection--stops discharge when battery voltage falls below 2.3 volts per cell (varies with manufacturer).
A fuse opens if the battery is ever exposed to temperatures above 100° C.

4.2V 0.8A li-ion battery charger

Nickel Battery Charging Basics

NiCad and NiMH batteries are amongst the hardest batteries to charge. Whereas with lithium ion and lead acid batteries you can control overcharge by just setting a maximum charge voltage, the nickel based batteries don't have a "float charge" voltage. So the charging is based on forcing current through the battery. The voltage to do this is not fixed in stone like it is for the other batteries.

This makes these cells and batteries especially difficult to charge in parallel. This is because you can't be sure that each cell or pack is the same impedance (or resistance), and so some will take more current than others even when they are full. This means that you need to use a separate charging circuit for each string in a parallel pack, or balance the current in some other way, for example by using resistors of such a resistance that it will dominate the current control.

The coulometric charging efficiency of nickel cadmium is about 83% for a fast (C/1 to C/0.24) charge, and 63% for a C/5 charge. This means that at C/1 you must put in 120 amp hours in for every 100 amp hours you get out. The slower you charge the worse this gets. At C/10 it is 55%, at C/20 it can get less than 50%. (These numbers are just to give you an idea, battery manufacturers differ).

When the charge is complete oxygen starts being generated at the nickel electrode. This oxygen diffuses through the separator and reacts with the cadmium electrode to form cadmium hydroxide. This causes a lowering of the cell voltage which can be used to detect the end of charge. This so-called minus delta V/ delta t bump that is indicative of end-of-charge is much less pronounced in NiMH than NiCad, and it is very temperature dependent.

As the battery reaches end-of-charge oxygen starts to form at the electrodes, and be recombined at the catalyst. This new chemical reaction creates heat, which can be easily measured with a thermistor.. This is the safest way to detect end-of-charge during a fast charge.

Nickel cadmium battery chargers should cut the charge off when the temperature exceeds the maximum charging temperature, typically 45 degrees C for a controlled fast charge, and 50 degrees C for an overnight or fast charge.

6.4v 0.6A nicd battery charger

Rust Removal the Scientific Way

Rust is one of the biggest culprits that make your possessions look unsightly and even render them useless when left unattended. Rust is iron that made contact with oxygen, and forms an unattractive stain in your metals and other materials in your house that contains or is made up of iron. Aside from employing various methods to protect your materials from the formation of rust, you can also use many rust removal products. Over the years, many rust removers have already been developed that are cost-efficient, effective and can save your materials from rotting with rust.

Metal rust removers come in various forms and techniques. One of the most popular ways of removing rust manually without the use of rust removal products is through electrolysis. If you have paid enough attention to your sixth grade science teacher, you would know that rust is a product of iron making contact with oxygen. So basically, the process of removing rust is the transformation of the surface reeking of rust back to its original form - iron.

All you need to use are the following: a stainless steel, a plastic tub, washing soda, water and a battery charger. Place a tablespoon of the washing or baking soda to a gallon of water. This serves as the removal solution. Clean the piece of stainless steel to be used for the rust removal process. It is crucial that the steel is cleaned enough to ensure that enough electric contact is achieved. Attach the positive side of the battery charge to the steel and submerge it in the soda-water solution. Attach the negative side of the battery charger to the material you wish to be cleaned. Submerge this piece to the solution as well. Make sure that the material and the stainless steel do not make any contact as this might lead to a short circuit. Now it's time to turn the battery charger on. If the current is too high, you can either increase the distance between the stainless steel and the material to be cleaned or add more water to the solution. Once done, you should see bubbles of oxygen and hydrogen in the solution. The time to wait before all speck of rust is removed varies on the size of the material and how much rust has accumulated on it.

9.6V 0.4A nimh battery charger

Cell Phone Accessories make Your Mobile Phone More Charm

Phone stylus, car charger, cell phone data cable, battery, all mobile phone accessories Bluetooth Headset unparalleled choice. All cell phone accessories, from the mobile phone sets, mobile phone charger, cell phone batteries, bluetooth headset, come up with a 100% satisfaction guarantee! These days, you can not get out in front of the store to buy one, with Bluetooth, screen protection and insurance planning, while protecting those gadgets seem easy to break. But of course, there are even more incredible awesome, must-have accessories.

Mobile phone accessories to enhance your phone you have a cell phone, odds are, you will never leave it home. But if you have low vision or hearing difficulties, and sometimes you may find that the phone may be a bit tedious and frustrating.

A cell phone only as useful as it is readable, it is very reasonable, to prevent dust and scratches in the screen. Our collection of transparent screen and shield crystal displays will continue to look for several days to clear. We have been in our mobile phone to become a good chunk of our lives these days. If you like to have photos, videos and other patrons of memory at your disposal, it might be a good idea to expand the phone's memory card and expansion pack capacity. When you are in so much as call waiting, there are no more nervous than see a "low battery" warning flashes on the screen tight. To fully charge your mobile life, the wall charger, USB cable, car units and portable battery extensive. Your phone's built-in battery, you should continue for a long time, but it will need replaced at some point. Around that time, we stock a full set of replacement batteries for all major mobile phone brands.

5v 2.1A micro usb car charger with 2 ports

How to properly use the charger

Car Charger. Such charger can easily charge the phone in the car. One end of the car charger is plug into the cigarette lighter, and the other end is connected to the phone, the phone should not be charged in the car for a long time because of the car closed with a high temperature, otherwise it will cause damage to the phone.

The original travel charger and seat charger adopt protect circuits or switch road design for the protective effect for rechargeable battery, while fake and shoddy charger without protected circuit is easy to burned or even burn the phone, choose the original travel charger and away from knock-off. "Auto resolution lithium or NiMH batteries"is a apparent key to identity a charger,which can automatically distinguish two different battery charger in case of "the discharge of lithium malfunction".If you accidentally press the "release pushbutton" on dock charger when charging lithium batteries, a good charger can identify lithium battery, it will not make a discharge operation; poor cradle will result in the impairment of lithium battery life. A good charger with protection settings and charging voltage standard does not overshoot or be unsaturated.

We shall keep safe using home appliances no matter what kind of we have bought, not to mention the phone,we must abandon some of habits without the security use of mobile phone especially when the phone is charged.

How to properly use the cell phone charger is the key to safe use of the mobile phones,if we do not pay attention to, we would not only get an electric shock, but may occur an explosion.

USB car charger

Merry Christmas & happy new year !

Unregulated DC Power Adapters

Regulated or un-regulated: what does it mean?
A voltage regulator is a device (usually an electronic circuit) that controls or maintains the constant voltage output of a power supply. Some (more expensive) DC voltage output power adapters have voltage regulators built in, while most do not.

Unregulated DC output power adapters are still the most common type of power adapter in use today. Unregulated, or "non-regulated" simply means the power adapter is not subject to the control or authority of a voltage regulator. With unregulated power adapters, or any other unregulated DC power supply, the DC output voltage is dependent upon an internal voltage reduction transformer, and related to the amount of current used by the electrical load. (The load is the device receiving power from the adapter).

Example: A given unregulated power adapter has an output rating of 9 volts DC at 500ma (500 milliamps = 0.5 Amps).
This rating means that the unregulated voltage output of the power adapter will be 9 volts DC when it is under the full rated load of 500ma. Many people are surprised when they plug an unregulated power adapter into a wall outlet and measure the DC output voltage of the power adapter with a volt meter. While the adapter is providing no power to a load device, the measured output voltage is several volts higher than the rated voltage of the power adapter. Often, people jump to the conclusion that something is wrong with the power adapter, while the simple explanation is that the power adapter has no voltage regulator, and this is normal. But if the same unregulated power adapter is connected to a load which draws 500ma of current, the measured output voltage of the power adapter would drop to the rated 9 volt DC output level as it should.

The second important concept to understand about any power adapter, whether regulated or unregulated, is that the rated output current of the adapter should not be exceeded by the maximum current requirement of the load.

Example:  If a power adapter has an output current rating of 500ma, it should never be connected to a load that will draw more than 500ma of current from the adapter. Drawing more than the rated current output from an unregulated power adapter will certainly cause the actual output voltage to drop below the rated value, and overloading any power adapter in this way will lead to overheating and premature failure of the adapter. Overloading a power adapter may cause a fire hazard and depending on the power sensitivities of the load, may cause damage to the load as well. Most power adapters made today, have built in overload protection (essentially an internal fuse to prevent the adapter from going up in a puff of smoke), but overloading the adapter may still cause it permanent damage. Appropriate external fuse protection can be added if the extra precaution is warranted.

A third concept about unregulated power adapters which for most applications is less important, but still helpful for people to understand, is that unregulated DC output power adapters do not produce a pure and "clean" DC voltage. But if the power adapter selected is closely matched to the power requirements of the load, the purity of the DC voltage produced is more than adequate for many jobs (with few exceptions).

12v 6A DC Switching CCTV power supply