Super NiMH Charger
John Geach, KS7R-
Over the years, I've used rechargeable batteries in alkaline battery packs for my 2 meter hand- helds and for building 12 volt battery packs for QRP backpacking radios. The first rechargeable batteries were Nickel Cadmium (NiCd) which suffered from developing memories if they weren't completely discharged prior to recharging. Nicads have generally been replaced by the latest Nickel Metal Hydride (NiMH) batteries. A NiMH battery can have two to three times the capacity of an equivalent size NiCd and the memory effect is not as significant. They hold up well under high current demands and are now available in capacities approaching 3000 mah. A good article on the characteristics, benefits and charging requirements of NiMh batteries and can be found on wikipedia.org.
A few months ago, I purchased some NiMh batteries and needed a good charger for them. After doing some internet research, I found several good references to chargers manufactured by MAHA Energy Corp. I decided to purchase their new PowerEx MH-C9000 Charger- Analyzer. Like many chargers it will charge up to four AA or AAA batteries. However, this charger has five operational modes that will charge, discharge and form your batteries to keep them in tip-top condition. It's micro-processor controlled and has a large LCD screen to monitor the charging/discharging cycle of each battery.
The "Break-In" mode allows the user to input the capacity of the battery and performs a "forming" charge designed to properly break-in new batteries. The "Cycle" mode allows user to charge and discharge batteries consecutively for up to 12 cycles. The "Refresh & Analyze" mode charges the battery, rest for one hour, discharge, rest again, then recharges it. The "Charge" mode recharges the battery at the selected rate and the " Discharge" mode discharges the battery at the selected rate.
There are ten selectable charging and discharging currents from 0.2A to 2.0A and 0.1A to 1.0A respectively. Each battery compartment is completely independent so you can be forming several batteries in a charge- rest-discharge cycle while normally charging another batteries at the same time.
The unit can be operated in either "basic" or "advanced" mode. In the basic mode, you just insert the batteries and the charger will select the appropriate settings automatically. In the advanced mode you can set the charging mode, battery capacity and charge/discharge rates for each battery.
I purchased mine from www.thomasdistributing. com and have been very impressed with its operation. The charger comes with a nice nylon carrying case and several plastic battery carrying cases to keep your charged and discharged batteries separate. Thomas's current price for this charger is $62.97.