CHOOS­ING A CHARGER

RC Car Action - - TECH-KNOW HIGH VOLTAGE -

Now that you’re set up with bat­ter­ies, let’s talk charg­ers. First and fore­most, make cer­tain that you get a NIMH charger if you have NIMH bat­ter­ies, and a Lipo charger if you have Lipo bat­ter­ies. It is vi­tally im­por­tant to get that right. If you use both types of bat­ter­ies, there are charg­ers that can be set for either bat­tery type. If you go that route, be sure to set the charger for the cor­rect bat­tery type be­fore you hit the “start” but­ton. As for charger fea­tures to look for, the most im­por­tant (af­ter de­ter­min­ing “Is it the right type for my bat­tery?”) is am­per­age. The higher the charger’s amp out­put, the faster it can charge your pack. The math is easy: just di­vide bat­tery ca­pac­ity by charger out­put. Let’s say you have a 5-amp charger and a 6000mah bat­tery. 6000 mil­liamp-hours equals 6 am­phours. Di­vide 6 by 5, and you get charge time in hours: 6 ÷ 5 = 1.2 hours. The higher the amp rate, the quicker the charge time.

HOW MANY AMPS?

Now, we know what you’re think­ing: “If more amps is bet­ter, why not get a 30A charger and blast that bat­tery full in just five min­utes?” That makes sense math-wise, and se­ri­ous rac­ers do ex­actly that. How­ever, they also re­tire their bat­ter­ies af­ter 30-40 runs, while the rest of us would rather get 300-400 runs out of our bat­ter­ies. Charg­ing at lower am­per­ages will ex­tend your bat­ter­ies’ lives— that means more recharges be­fore the pack no longer per­forms well enough to be worth keep­ing. For max­i­mum life, charge Lipo packs at the same rate as their ca­pac­ity. For ex­am­ple, if you have a 4000mah Lipo bat­tery, charge it at 4A. If you have a 5500mah bat­tery, charge it at 5.5A. And so on—just take the bat­tery ca­pac­ity and di­vide by 1000. In the lingo of bat­tery charg­ing, this is known as charg­ing at a rate of “1C,” or “ca­pac­ity mul­ti­plied by one.” If you want to speed things up, charg­ing at higher rates up to “2C” (twice the bat­tery’s ca­pac­ity; for ex­am­ple, 8A for a 4000mah pack) is fine, but do most of your charg­ing at a lower rate when­ever you can.

Rac­ers use high-pow­ered charg­ers like this Max­amps Hype­r­ion EOS 0840i to blast their bat­ter­ies at 30A or more. This type of charger re­quires a sep­a­rate DC power sup­ply, and a com­plete setup can cost over $300.

You don’t need this level of gear for fun-run­ning.

Traxxas’ Ez-peak id charg­ers au­to­mat­i­cally de­tect bat­tery type, cell count, and ca­pac­ity when used with Traxxas id bat­ter­ies.

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