Li-Po - Don't want to burn to death.

[Bravo]

What is the difference between 2S and 2C ?
I have a FTX VoltZpower FTX 2552 7.4V It's 5000mAh. Bought a week ago. All this stuff is bought a week ago.
I have a Li-Po charger that says it can do Max 4A and 2C.
I don't understand any of this new stuff.
I thought I set it to 2C. I set it to Max charge ampage of 3.5A.
Seemed to charge for 50 mins and then went to 0.3A and then stopped.
But it was saying the voltage was 8.66V when it finished.
Have I overcharged this thing ?
The charger was hot at the beginning before the ampage dropped.
The battery never even got warm to the touch, never mind hot.
I have seen film of these things going off when they are mistreated. I didn't go far away ! Don't want that happening !
No harm done I suspect.
But should I be charging at 1C/S. ?
2C/S ?

[sosidge]

What model charger is it you have? That might help.

8.66V is worrying. LiPo cells are supposed to reach 4.2V per cell - 8.4V in that 2-cell pack. Lipo charger do decrease the current at the end of the charge.

LiPo language now...

"s" normally refers to the number of cells in series. 7.4V packs are "2s"

"C" is a measurement of charge/discharge rates compared to capacity. It wouldn't normally be used to describe the charger, just the cell performance - for example, a "35C" pack can maintain a discharge rate of 35 times the cell capacity (for a 5000mAh pack, that is 175A). C ratings are prone to be inflated for marketing purposes though. Some cells may also say that they can be charged at "2C" or "4C", although the BRCA guideline is to charge at 1C (5A for the 5000mAh pack).

[Bravo]

Going upstairs to get the box this stuff came in.
Will reply shortly.

[Bravo]

Charger is a Fusion Ethos LX41B made by Logic RC Ltd

[mark christopher]

defo should only get 8.4 volts max on charge, if you were to race at regionals or nationals with packs that high your out.................

do you have a seperate volt meter any where to check the battery is actually what the charger is saying?

cherger will get warm when at higher amperage, the amps should drop when the volts get to 8.4, lipo use a CV charge (constant voltage), id be worried bout the 8.6 volts, BUT its not going to make them explode or catch fire

id set 1c charge for 7.4v 2s cell so a 5000mah pack would be 5 amps for one charge) or the max your charger can do 4.5amp?

[Bravo]

This thread is by no means dead. Anyone else to say,,,,,, come.

[Bravo]

So, what's the diff between 2C and 2S ?

[Bravo]

So, given the reply by the above, I should just be sticking to 1C ?

[mark christopher]

Originally Posted by Bravo

So, given the reply by the above, I should just be sticking to 1C ?

c is coloumb,
but think of it like this
1c is refered to as 1x Charge rate

so if your pack is 5000mah, 1c is 5 amps

if its 20c rated pack it means it can dicharge or give an output of 5000mah x 20c = 100 amps

1s is one cell in serries which would give you 3.7 volts (nominal value of a lipo cell)
our packs (7.4volts) are 2s = 2 cells in serries

some good info here

http://www.trakpower.com/index.asp?page=lipoExpert.asp

http://www.flighttech.co.uk/newsOpen...sp?articleID=6


good cell layout graphics from jimmy here
http://www.oople.com/rc/photos/reviewtrakpowerlipo/

[Bravo]

Yes got it.
In future I will stick to a 1C charge at 3.5 or 4A (which is max for my charger).
And will tell my charger it's a 2S (meaning 2 cell).
Thank you and happy driving.