Lithium Polymer or LiPo batteries are a great new way of storing energy for portable devices from cell phones, home electronics to RC hobby battery packs used in cars, boats and flight. They’re great because they can store 350% (approximately) more energy than a typical NiCd/NiHm battery pack and weigh 10% – 20% less. They can also discharge much more current than a NiCd/NiHm battery and can be fully charged in about an hour. LiPo batteries also don’t develop memory or voltage depression characteristics like NiCd/NiHm batteries, and do not need to be discharged before being charged.
But they’re not without their downside. Mishandling of these batteries can lead to fire, explosions and toxic smoke inhalation. In the rest of this guide we will cover safety guidelines of charging and handling Lipo battery packs. Some may seem pretty obvious, but it is often the obvious things that are the most dangerous when ignored. Another good resource is our rc car batteries lipo info. This page is a very good resource on Lipo battery ratings and terms and if you are new to Lipo technology we recommend you read this as well.
Charging Lithium Polymer or LiPo batteries have very specific charging requirements and MUST only be changed by specific chargers designed to charge 3.7 lipo battery. We recommend only balance charging your lipo batteries. All good quality Lipo battery packs come with 2 leads. The main charge / discharge lead and connector and a balance lead and connector. Using a computerised balance charger to charge your Lipo batteries will ensure that all the cells in the battery pack have the same voltages. The voltage value is critical to the condition (during use) and safety of each cell, which we will cover more in this article.
“1S” or 1 cell LiPo battery has a nominal voltage of 3.7v. When fully charged it has a maximum voltage of 4.2v and when fully discharged, it should never go below 3.0v without risking cell damage. Based n this logic “5S4P” battery pack means that the pack contains 5 cells in a series circuit and 4 cells in a parallel circuit. Since each cell is 3.7v (nominal) a 5S LiPo battery has a nominal voltage of 18.5v, a fully charged voltage of 21.0v and a maximum discharged voltage of 15.0v before damage occurs.