Ramsey Electronics DN1 manual Introduction

INTRODUCTION

With today’s ever changing technologies, more appliances depend on battery power to enable their use. While this gives us greater freedom, it is often at the high cost of purchasing portable energy, or batteries, to run our portable electronic gismos. Consider the cost of energy from our local electric

company, about 8¢ for a KW hour, or about 450,000 joules of energy for a penny. On the other hand, that 500 mA-H NiCad that you just purchased for about $1.75 can only supply 2250 joules of energy; that's about 13 joules for 1 cent. So it’s fairly easy to see that energy costs about 35,000 times more when it’s in a battery.

Nobody likes the idea of throwing all those batteries into a landfill. That's the reason for the recent emphasis on using “green” rechargeable cells. If a set of NiCad cells lasts you for a few months, they can save the equivalent volume of themselves many tens or hundred times in the trash. This is not only good for the environment, it’s also great for the wallet!

Nicad rechargeable batteries have been around for years, but there are a few real disadvantages in their use. They usually require a long time (sixteen hours) to recharge. This “trickle charge” arrangement is quite common because it is much cheaper for the original product manufacturer to produce (the entire battery charger is typically a couple of rectifier diodes and a current limiting resistor), and works well given the draw back of a long charge time.

Another disadvantage to the “plug-in wall transformer charger” is that the charging cutoff action is regulated by the heat produced by the cells’ chemical reaction when recharging. If you’ve ever opened up a rechargeable pack you have probably seen the thermal shutoff “mystery part” connected and mechanically touching one cell of the battery pack. While this will help if you leave your appliance charging for several days, notice that it is sampling only one cell in the pack, and assuming that the rest of the batteries are “behaving” in the the same manner. Also, since the ambient temperature can change (i.e.recharging your cordless drill in the cool garage or basement, or your two way radio on the hot seat in the car), this heat sensing approach can vary considerably from undercharging your pack to overcharging until you “cook” the electrolyte solution right out of the battery.

Often times we cannot wait for the full recommended charging time or do not use the batteries until they’re completely “dead”. When this is repeated, the uncared for battery or pack can seem to “run out” rather quickly. This effect is caused by not completely discharging the cell before it is recharged and is known as the memory effect, since the battery appears to memorize the amount of energy it is called upon to produce.. By not completing the

DN1• 4