NiMH is short for nickel metal hydride while LiPO is short hand for lithium polymer. Both of these types of batteries are currently being used in the electric model RC car scene. Most ready to run RC model cars will include some form of battery -to keep costs down, they are usually the NiMH variety. LiPo battery packs really came on to the RC model scene powering model airplanes and helicopters-taking advantage of their light weight and superior power density.
Thanks to a robust and highly competitive RC car racing environment, LiPo battery packs are definitely the newer and preferred power source for today's' power and speed hungry RC car customer base. LiPo batteries are now even taking over the common consumer products-powering most high end cordless power tools, as well as near 100% of the laptops and cell phones currently produced! So what exactly is it that makes LiPo batteries so popular with the RC car crowd? Well, with a number of Chinese manufacturers fighting for market share, prices have become so cheap and available so high via the world wide web. Of course, besides a lower price structure from just a few years ago, the performance and capacities of the battery packs have improved as well. There are more sizes to choose from, and now there are RC Car specific packs rather than those originally sized for model airplanes. The chargers for LiPo battery packs have also become less expensive and generally easier to use; probably one of the more likely reasons for people venturing to the LiPo side with a now lower investment. The lithium polymer chemistry of the LiPo battery pack is also inviting. With a higher power density-lower weight with same or higher voltage and current output than NimH, the speediest of all RC cars will be running some form of LiPo power pack. Current world record speed holders are now powered by LiPo batteries rather than banks of Nimh cells!
So is NimH dead? Well that question can be answered as NO. They are the most powerful battery pack for a RC model car …. that answer is also no. What matters is what the application requires. Low cost is still a factor in favor of NimH despite cheap lipos littering the market. Nimh uses technology that is now 20 years old. With that in mind, simple chargers are very easy on the budget, and most NimH factories produce excellent battery packs with experienced processes and quality control. Safety is still on the side of the NimH battery. There is still less of a chance of fire / explosion caused by over charging with a Nimh vs. LiPo battery. Durability is still on the side of NiMH battery packs as they can be run down to near zero volts whereas that would ruin a LiPo battery. A fourth, almost contrarian view, is that NimH batteries weigh more and put out lower voltage …. an actual plus for controlled club racing and beginners. A "loose" off road track may be better traveled with a Nimh battery offering more traction and less power to break the tires' grip. A good Nimh battery can still offer the same number of charge-discharge cycles as a Lipo battery-and without special balance chargers that Lipos require. For someone who may have reentered the hobby but still has equipment-they may choose to still use NiMH batteries.
All in all, it really depends on ones budget and application. Many hobbyists have both NimH and LiPO battery packs. Some will bash with either battery -do speed runs with lipos-or whatever they choose. With Lipo battery packs becoming cheaper, especially as new hobbyists and lipo friendly equipment enter the market, we can guess that Nimh will become less of a choice for the consumer.
Nimh and LiPo battery packs require different care in use, storage, and charging. We will cover this in an upcoming article.