kashif314

Hi Guys,

Trust you ll be fine. I have a Traxxas Rustler VXL and I installed a 3 s 4000Mah Lipo Battery. Since I am new to this hobby and don't know much about Lipos so I bought a cheap non digital charger. There are 3 Switches on the Charger 1A, 2A, 3A and the Hobby shop sales man told me to charge the battery on 3 A because its 4000mah and otherwise will take a lot of time but I am still in doubt, so I am asking you guys to please tell me that if its ok to charge on 3 A or shall I go for a low setting like 2A or 1A and please tell what is the difference among all and what is best and safe for 3 s 4000mah lipo.

Please Reply,
Thanks a lot.

collector1231

My Feedback: (1)

3 amps is good. To find the recommended/safe charging amperage on any battery, divide the MAH by 1000, and subtract .5. That is the suggested amperage you should charge that particular battery at. Any thing under that is okay, but go with the number closest to the one you just did all the math for.

kashif314

Thanks a lot bro for the detailed explanation. This formula you told me is of great help. Once again big big thanks bro

ptgarcia

My Feedback: (36)

1C charge rates are acceptable for just about any battery.

RustyUs

Quote:

Originally Posted by ptgarcia

1C charge rates are acceptable for just about any battery.

Totally agree with ya there ptgarcia, if the pack doesn't have any kind of recommendations of charge rates, the safe old school 1C charge rate should apply...e.g. 3000mah = 3 amps; 4000mah = 4 amps; 5000mah = 5 amps...etc. etc. etc.

My first LiPo batteries I bought were Win-Max 4200mah Nano-Platinum packs and they are rated for a MAXIMUM charge rate of 10C (4200mah x 10C charge rate/1000 = 42 amps). There is no way my chargers could crank out 42 amps; most chargers won't even come close to that kind of power. My chargers only put out 80 watts of maximum power and have a maximum charging output of 6 amps. I just balance charge all my packs (even the ones with no specified charging rates) at the 6 amp setting; using 2 chargers most days to get things done. Most of my LiPos are 4 years old and still going strong.

I should note that all my LiPo packs are 4000mah or greater. I would not recommend charging, let's say, a 1200mah pack @ 6 amps unless it's rated at a 5C charge rate.

chuckk2

[QUOTE=kashif314;12059800]Hi Guys,

Trust you ll be fine. I have a Traxxas Rustler VXL and I installed a 3 s 4000Mah Lipo Battery. Since I am new to this hobby and don't know much about Lipos so I bought a cheap non digital charger. There are 3 Switches on the Charger 1A, 2A, 3A and the Hobby shop sales man told me to charge the battery on 3 A because its 4000mah and otherwise will take a lot of time but I am still in doubt, so I am asking you guys to please tell me that if its ok to charge on 3 A or shall I go for a low setting like 2A or 1A and please tell what is the difference among all and what is best and safe for 3 s 4000mah lipo.



The one C rate for a 4000mah Lipo is 4A. anything under that is considered acceptable.
Lets look at another detail.
using 4.00 v per cell (since most of the charge time will be at voltages below 4.0v)
4x3 =12 (volts)
W=IE
12Vx4A =48W
So, at first glance, a 50W charger would just be adequate to charge the Lipo.
But, figuring 80% efficiency, you would expect about 38W as a maximum from the 50W charger.
Thus, an 80W charger would be better, at an expected 64W usable capability.
2C is a fairly common safe charge rate for the typical Lipos we use.
Obviously, this doubles the current and wattage needed to charge.
When you figure expected charging time, the amount of time needed to balance the lipo
can be significant, and increases when the Lipo has mismatched cells.
Also, the charger's balance current capability (and settings) can make a large difference.

Charge rates above 2C or so can shorten the useful life of a Lipo, even when it's rated at say 5C.