Worldwide Use Possible
This means that the charger can be used around the world; this is because they can run of an input voltage of 100V – 240V AC. In the UK, standard mains voltage is 240V; however in different parts of the world 100V is used. Some of the chargers which are marked to work worldwide come supplied with a primary plug set for the different regions, others will need separate adaptors. Double check the product information or contact us if you are not sure. Ideal if you need to take your charger travelling.
12V DC Input for in car use
A charger which has this functionality will come supplied with a cigarette adaptor so you can run it from your car, caravan or mobile home, anywhere that you can gain access to a 12V DC (Direct Current) input. This functionality is ideal for those looking for a charger to take on their travels.
Charge Termination
Most modern charges are intelligent chargers; this means they use a microprocessor to control the charging of the batteries inserted into the charger. There are a number of different methods of controlling the charge which are all designed to protect the batteries from overcharging and maintain battery performance
-ΔV Detection
This reads ‘minus delta V’ or ‘negative delta V’ and this is the most common method of end of charge detection for NICd and NiMh batteries. When a battery is used, its voltage decreases and it will get to a point where it does not have enough voltage to power the device it is in and needs to be recharged. Charging the battery basically increases the voltage to its original state by applying a constant current to the battery.
Towards the end of charge, the voltage will reach a peak and will not be able to rise any further; at this point, if current is continued to be applied the voltage will begin to fall. This is the danger zone because at this point the battery is not converting the charge current into chemical energy to charge the battery, a different reaction is taking place which causes oxygen to build up inside the battery (called polarisation) and cause a rapid rise in temperature which if continued will cause damage to the battery.
-ΔV detection is used to detect the drop in voltage from the peak to either reduce or stop current being applied to the battery. It needs to detect this drop quickly to minimise the risk of overcharging and this is where its name comes from:
‘-‘ or ‘negative’ indicates a fall or drop
‘delta’ means a small change
‘V’ indicates the voltage of the cell
Safety Timer
Many chargers have an inbuilt safety timer which will either stop the charge current or reduce it to a trickle charge once the set time is reached. This feature is present on some chargers that are not intelligent just as a basic safety system however it is most commonly seen on fast chargers as a secondary safety feature to protect against overcharging. They are generally set at a fixed time regardless of the inserted batteries. One thing you need to be careful about with chargers with safety timers is that there may be a limit to the capacity of batteries you can charge. In order to check this you can use the following formula:
Maximum Battery Capacity = (Length of safety timer x Charge current)/1.2
For more information on this formula take a look at our ‘Want to calculate your own charge time?’ section.
Temperature control
Temperature control is most often seen on fast chargers because at high charge rates, batteries are more prone to overheating and this has to be controlled carefully to avoid damage. Chargers with contain temperature control will monitor the temperature of the inserted cells and if they get too hot it will perform some action to bring the temperature of the battery back down again. This may either be reducing the charge current to a trickle charge, resting the battery or stopping the charge altogether. This is an advanced feature and will mainly put in as default by manufacturers of fast chargers or advanced chargers with high cell maintenance characteristics.
Individual Supervision of Cells
Most consumer chargers have the capacity to charge more than one battery (cell) at a time, generally four or more. With some four cell chargers you must put 2 cells in at a time or the charger will not work. Chargers which have individual supervision of cells can charger any multiple of cells at one time. There are a number of reasons why this is a desierable feature to have:
1, If you have a device that runs of say 1 or 3 batteries, you only want to charger the batteries you are using,
2, The inserted cells may be at varying states of charge so the only way to ensure each cell gets fully charged without the possibility of damage to the cell is to have individual supervision of cells.
When chargers require multiple cells to be inserted to the charger to begin the charge process, it will apply the same charge regime to that multiple of cells. If it has Individual supervision of cells, the state of each individual cell will be monitored throughout the charge process; when the each cell if fully charged the appropriate cause of action will be taken on that cell, other cells that are not fully charged, the charge process will continue.
Faulty Cell Detection
Rechargeable cells as with primary non-rechargeable have a finite service life and reach a point where the cells are dead. At this point the cells will not hold their charge or will not be able to take any charge at all and will not function correctly in their application. The time it takes for a cell to reach the end of its life depends on the type of use, they way in which they are charged, stored and maintained; a general rule of thumb is that NiCd and NiMh cells will last between 500 to 1000 charge/recharge cycles.
When a cell reaches the end of its life, it is pointless attempting to recharge it, it wastes both time and power in trying to recharge a dead cell and you will only know that the cell is dead after recharging it, inserting it into your device then finding it fails. This can be a major problem if it is critical that after charging that cells you rely on them to power your device effectively and for the required time. Most intelligent chargers have a function that checks the ‘state of life’ of a cell to determine if it is faulty/dead and therefore can no longer be used. If the charger determines a cell is faulty it will indicate the fact and won’t charge the faulty cell; this helps you identify when a cell is dead before having to wait for your device to fail.
Automatic Battery Analysis
This is a feature that is only present on three of the chargers we stock, the Ansmann Energy Series, Energy 4, Energy 8, and Energy 16. This feature analysis the inserted battery and checks its current state of charge and the overall condition of the battery. From this information the charger will either simply charge the battery as normal, discharge the battery before charging or recondition the battery by pulsing the battery before charging it ensuring that that the battery will always be maintained to the highest level each time it is charged.
This is quite an advanced feature and the price of these chargers shows this however if you want to ensure that you get the best out of your batteries then the chargers with this feature and some of the best on the market.
Refresh Function
As with the Automatic Battery Analysis feature, the Refresh function is only available on the Ansmann Energy Series of chargers. The refresh function starts automatically on inserted batteries which are detected to have low capacity after the battery analysis stage. During the refresh cycle, the inserted battery is pulse charged and discharged over a period of time. The charger applies a pulse charge then discharge current to the battery which stirs up the electrolyte inside the battery to allow electrons to flow through the battery more easily and in essence refreshing the battery and extending its service life.
This is an excellent feature to ensure that you get the longest life out of your rechargeable batteries; it is also very good if you store your batteries for a long period of time in between use because sometimes after storage batteries can loose some capacity and need refreshing to bring their capacity back up to an appropriate level.
Capacity Quick Test
This feature is like a mini test of the inserted battery so you can get an idea of what state your batteries are in. There are various LED’s on the chargers and these give an indication of the approximate capacity before charging begins. This will not give you a precise reading of the capacity of the battery but it will give you an idea so you can decide if you wish to charge the battery or not.
This feature is very useful if you have quite a few batteries and you want to keep track to their state of charge, it can also give you an idea of what kind of usage you are getting out of the battery after each charge.
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