Q:I have several products that use the new Lithium-ion (Li-ion) batteries. The people who sold me the equipment implied better performance compared to the Ni-Cds with respect to "memory" (when the battery loses capacity with repeated charges, especially when not completely discharged before recharging). However, my Li-ion batteries seem to have a memory problem similar to what I experienced with the Ni-Cds. Are these new batteries defective or am I the victim of hype?
A:Lithium-ion batteries are indeed higher capacity and much less susceptible to "memory" problems. But this highly advanced battery technology requires a more advanced charger as well as some understanding of how this battery's characteristics vary from those of Ni-Cds. Li-ion batteries are more particular about charging conditions. It is this aspect that may be the cause of your problems. You didn't say at what temperatures you charge your batteries. Li-ion battery chargers have intelligent circuitry that prevents damage to the batteries. If the ambient temperatures are above 119Â° F (45Â° C) or below 32Â° F (0Â° C), the charger may actually shut off or greatly reduce the charging process. So the cause of your problem may be due to the conditions under which you charge your batteries. For instance, if you re-charge your batteries in the field (i.e. your truck) on a hot summer day with the windows closed and the air conditioning off, or on an extremely cold winter day, it may be that there is little to no charging occurring because the intelligent circuitry of the Li-ion battery charger has limited or completely stopped the charging current to prevent damage to the battery. There is also an optimal Li-ion battery operating temperature range, but that is considerably wider than the operating range. Since battery technologies are constantly being improved (even for Ni-Cd), we strongly suggest you contact your manufacturer for more information specific to your batteries. Finally, be aware that even though it is outside the scope of this column's discussion, all battery technologies have optimal charging and operating temperature ranges.
Q:Instead of using a thermometer and barometer to measure atmospheric conditions to set the PPM atmospheric correction value on my EDM, I use a 100-ft tape to determine the correction. I stretch it out and set my EDM at one end and my prism pole at the other end. Then I vary the PPM settings until I read 100.000 ft. I attended a seminar recently where the speaker said this wasn't the right thing to do. Why?