RXT07

HELP please
Just got Hexfly HX403 charger and an additional LiPo battery (Hexfly 3500 lipo 7.4v 20c). RC came w/ the 3200 lipo and an incredibly slow Hexfly charger, but this one isn’t charging any faster and I’m certain its a matter of settings. Read the instructions and they are like another language since I have absolutely no experience w/ these (only had RC for 2 weeks, bare w/ me)
thanks!

RustyUs

http://www.rcuniverse.com/forum/redc...fly-hx403.html

The maximum amperage is 3A (amps). If charging two 2S packs, the maximum charge rate is 1.5A for each channel. If you want quicker charge times, you are gonna need a more powerful charger.

RustyUs

My question to you is, how "fast" do you think "fast" should be? With that new charger, charging two packs at less than half a 1C charge rate, it will take well over two hours for charging to be completed. Something like a Hitec X-1 Mini AC Balancing Charger would be better suited. Heck, even two of those chargers would be a decent deal for a person charging 2S~4S battery packs.

RXT07

We are essentially charging one at a time while the other is in use on the car. On “how fast”; the manual that came with the RC (its a Redcat Blackout XTE Pro not sure if that matters) along w/ their website had this charger listed as a recommended upgrade and showed a potential charge time for a 3200-3500mah battery of around an hour an half or less vs the orig charger that was taking just short of 4 hours. 1:15-1:30hrs, anything under 2 hrs is manageable; 4 is really difficult for a kid that just really wants to play w/ his rc car after school before it gets dark, lol, which is why he got the upgraded charger and extra battery. Im just as new to this as him and want to be sure theyre set right/charging right (& as quickly as poss) and the directins dont make a lot of sense to someone not familiar to this stuff. Sorry for the nieveness; Im mom, grew up w/ 4 wheelers, not RC cars

RustyUs

Recommended charging rates are normally @ a 1C rate for safety and longevity of battery.

From Roger's Hobby Center LiPo guide: "The equation works the same way as the previous discharge rating, where 1000mAh = 1A. So, for a 3000mAh battery, we would want to charge at 3A, for a 5000mAh LiPo, we should set the charger at 5A, and for a 4500mAh pack, 4.5A is the correct charge rate."

Your Redcat recommended upgrade for a charger can't charge your LiPo packs at a 1C rate. Which would be 3.2A for your 3200mAh pack, and 3.5A for your 3500mAh pack. So 1½ hours would be a good approximation of time it would take to charge your packs.

RXT07

Thanks for your help RustyUs! If I’m understanding right from what you’ve said it should he set to 3.x A, I still didn’t understand the 2s/3s/4s stuff & had to look up; (charger allows me to set up to 4.0A and has 2/3/4s plug in spots) but to determine the “s” part its volts divided by 3.7?? Is that right; these batteries are 2s?

RustyUs

The link in earlier post ( Roger's Hobby Center LiPo guide) explains what numbers mean on a LiPo battery pack...

"A LiPo cell has a nominal voltage of 3.7V. For the 7.4V battery above, that means that there are two cells in series (which means the voltage gets added together). This is sometimes why you will hear people talk about a "2S" battery pack - it means that there are 2 cells in Series. So a two-cell (2S) pack is 7.4V, a three-cell (3S) pack is 11.1V, and so on."

When charging, a LiPo battery is full when each cell's voltage reaches 4.2v. A two cell LiPo pack will have an ending voltage of 8.4 volts (4.2v + 4.2v). The Hexfly HX-403 charger (per website/manual) only allows 3 amp charge rate for charging a single 2S LiPo pack. If charging two 2S packs, the maximum charge rate is 1.5A for each channel. If your charger allows you to set the amperage to 4A, then you got a special one.

RustyUs

Redcat website image and what Redcat does not tell you about your charger....a page from same charger's manual that bias offers. ...