Lithium-Polymer batteries are often confused with Lithium-Ion or non-rechargeable Lithium batteries. They differ from Lithium batteries in three major ways: LiPos are rechargeable, they have non-standard shapes and a nominal cell voltage of 3.7 volts.
The main difference from Lithium-Ion batteries is that LiPos have a non-liquid dielectric and are (sometimes) capable of higher discharge rates of 20C and greater. The dielectric’s thick consistency means that LiPos do not have to be encased in a container.
LiPos come with a few “Cautions” attached, mostly due to the fact that they can catch on fire if improperly charged or if discharged higher than their rating. Never charge LiPos at a rate greater than 1C and don’t leave them unattended while charging. A lot of these warnings are due to the conditions under which LiPos are most commonly used: to power electric motors in R/C airplanes at or near their highest discharge rate for extended lengths of time. QRP rigs don’t discharge batteries at this rate or duty cycle. The same precautions exist for the Li-Ion batteries in your cell phone.
Although LiPos are initially expensive, they are rated for 300-500 charge/discharge cycles. My sources for these batteries are listed at the bottom of this page.
|Three small LiPos discharged at a 300 mA rate – the 250 mAh battery is absolutely tiny & weighs the same as 7 US pennies! A LiPo battery charger typically costs $30-$50. Battery prices, weights and cost per cycle (including $50 charger and assuming only 300 cycles):
|Also discharged at a 300 mA rate, this is the LiPo equivelant of an 8-cell pack of AA alkaline batteries – except that this LiPo weighs less, lasts longer and has a flatter discharge curve.Despite its small size, this battery has a safe continuous discharge rating of 30 amps! It weighs 4.9 ounces, costs $64 initially and $ 00.38 per cycle to use.|