5hr Charger
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You can probably find a large selection of time-based chargers in the market today. However, there is only a handful of them which features a relatively high fast charge current at a affordable price. For this review, a 5 hours fast charger and a set of Sanyo Twicell 700 were selected as a budget package for those who are sourcing for a low-cost yet efficient means of powering your AA/AAA sized dry cell powered device.

The five hours plug-in charger can recharge both Nikel Cadium (Ni-Cd) and Nikel Metal Hydride (Ni-Mh) rechargeable batteries. It is a compact charger that can recharge AA and AAA sized rechargeable batteries. As you can see, it has two compartments to cater for the two sizes. The lower compartment is designed for AAA sized batteries while the larger top compartment houses AA sized batteries. It can simultaneously recharge up to four similar sized rechargeable batteries or in a combination pair, i.e. two AA sized and two AAA sized rechargeable batteries.

Many people would probably not bother about checking out the specifications for the charger that they purchase. It is however, important to take note of specifications for the primary and secondary circuits to ensure that

     1)  An appropriate AC supply is available for where the charger is to be used.

2)  The charger is capable for fully recharging the batteries in a time frame which you are comfortable with. As a rough estimation, use this formula to compute the charging time required:

          Charging Time (in minutes) = [(Battery Capacity / Charge Current) / 0.8] * 60

This 5 hours fast charger uses a 2 round pin plug design (for plugging into the AC wall socket).  The specifications are as follows:  

As for the Sanyo Twicell 700 HR-4U, it is a rechargeable Ni-Mh manufactured in Japan by Sanyo. It has a rated voltage of 1.2V (suitable for most devices that requires a primary cell of 1.5V) and a battery capacity of 700mAh (currently the highest battery capacity for the AAA size). A higher capacity battery will have a longer life before a recharge is required.

Actual Performance

The batteries were discharged using a 300mA current draw to ensure that the measurements taken reflect a fully discharged state to begin with. Voltage readings were taken with a multi-meter and the fully charged batteries were given sufficient time for the voltage to stabilise after the fast charge process.

Conclusion

For a compact entry-level charger at an affordable price, this fast charger does not disappoint.  It has a respectable charge current level that is lacking in many other chargers within this category. Many compact chargers are commonly rated at only 125mA to 150mA of charge current, hence taking a longer time to fully recharge a battery. This charger is sturdy and well made. It is relatively easy to insert and remove batteries from the charger since it has a well-designed battery compartment. The added feature of automatically switching over to trickle charge mode is certainly useful as I often forget to remove the batteries once they are fully charged.

As with all products, there is room for improvement. It would be nice if this charger is microprocessor equipped to determine the state of the battery instead of relying on a fixed timer scheme. It is still possible to overcharge batteries based on a fixed timer scheme if one is not careful. It can only support rechargeable batteries with capacities of 1000mAh and below. This should not be a problem for AAA sized batteries but it will put a limitation on the choice for AA sized batteries.  Of course, adding more features to this charger would most probably priced it beyond an affordable entry level. For those who are looking for an intelligent charger that supports higher capacity batteries and shorter charging times with all the bells and whistles, please refer to the Intelligent Charger/Compact Intelligent Charger featured elsewhere at this site.