Basic Lipo charging info...

bicyclemonkey

Flying Derp
Mentor
I'd never heard that. I'll have to check the manual on my chargers. I have several batteries for each plane so I've always just run them down at the field and charged them at home. I've been thinking about setting up some kind of field charging station. The crazy heli guys at my field have these insane chargers in samsonite like cases and they all charge right after they land.
 

colorex

Rotor Riot!
Mentor
I'd never heard that. I'll have to check the manual on my chargers. I have several batteries for each plane so I've always just run them down at the field and charged them at home. I've been thinking about setting up some kind of field charging station. The crazy heli guys at my field have these insane chargers in samsonite like cases and they all charge right after they land.

Well, I might be wrong then...

Here's the manual for my charger:

http://www.hobbyking.com/hobbyking/store/uploads/647828718X220650X55.pdf

I checked, and I saw my mistake, I must have read too quickly...

I'll rephrase the comment above.
 

pgerts

Old age member
Mentor
I have never had any tester say anything like that to me - just displaying the cell voltages.
How low did you discharge your battery?

LiPos are used in cars (full size) and they are charging with braking energy - charging-discharging all the time.
 

jetpackninja

More combat please...
Mentor
Interesting Andre- can't explain the error activity on your charger. But your edit is correct, you shouldn't attempt to recharge warm batteries.
 

colorex

Rotor Riot!
Mentor
Interesting Andre- can't explain the error activity on your charger. But your edit is correct, you shouldn't attempt to recharge warm batteries.

I believe it's some kind of a voltage drop or bad connection, because it's a balancing charger and shouldn't have unbalancing issues...
 

fred0000

Senior Member
plugging it in that soon after the battery died (lipo cutoff) the cells may in fact be below 3.0v per cell and the charger wont charge a cell that low, after sometime the cell can creep back up to above 3.0v per cell and it'll then happily charge your cells.
 

colorex

Rotor Riot!
Mentor
plugging it in that soon after the battery died (lipo cutoff) the cells may in fact be below 3.0v per cell and the charger wont charge a cell that low, after sometime the cell can creep back up to above 3.0v per cell and it'll then happily charge your cells.

Yay! so I got a point! I think that's exactly what happened, because it only took 5 seconds to plug in the charger after the battery went down. Though my ESC should have been set to high voltage cutoff...
 

mkisaacs

Junior Member
So what does it matter if a charger is 50w or 200w? What difference does that make?

It depends on your battery mAh and voltage, and how fast you want to charge them. Here are some examples
Watts needed = Volts x Amps
For a 3s 2200mAh battery, charging at a 1C rate (2200mA which equals 2.2A), you would need to calculate as follows:
3s = 11.1V 1C rate 11.1V x 2.2A = 24.42 Watts
3s = 11.1V 2C rate 11.1V x 4.4A = 48.84 Watts
Minimum 50Watt output charger required for these.

If you wanted to use a Hyperion G3 or similar battery that is capable of 5C charge rates
3s = 11.1V 5C rate 11.1V x 11A = 122.1 Watts
50 Watt output charger won't work for this.

If you were charging 2 2200mAh batteries simultaneously, in parallel, at a 2C rate:
you would need 2.2A (for 1C) x 2 (for 2C rate) x 2 (2 batteries in parallel) = 8.8A
11.1V x 8.8A = 97.68 Watts
you would need at least a 100Watt output charger or greater for this to work.