Lipo Charging

[coleman758]

i have a 4000mah 2s 40c lipo. and a sigma 2 charger.

what would be the best amp to charge this as its variable?

[neiloliver]

Do not exceed a 1C charge rate, so 4A maximum. Constant Voltage to be set at 8.40V

N

[sparrow.2]

Recommended charge rate would be 4A, which is 1C. Depending on the type of Lipo you can charge at up to 2C or 8A safely but most clubs won't like it and might start getting huffy about it.

[mark christopher]

Originally Posted by sparrow.2

Recommended charge rate would be 4A, which is 1C. Depending on the type of Lipo you can charge at up to 2C or 8A safely but most clubs won't like it and might start getting huffy about it.

BRCA stronly advise 1c max

[coleman758]

I'm new to lipos so i'm kinda clueless!
its set to 0.1A at the moment so i presume that will do jack all!

so if i set it at 4.0A it should charge fine?

[sparrow.2]

Originally Posted by coleman758

I'm new to lipos so i'm kinda clueless!
its set to 0.1A at the moment so i presume that will do jack all!

so if i set it at 4.0A it should charge fine?

0.1A will do nicely if you want to wait until next christmas to drive your car.

4A will do fine.

[neiloliver]

Hope this helps...

A Lithium polymer cell operates between 4.2V when fully charged at 3.0V when fully discharged. It has an average voltage of between 3.6V and 3.8V. You charge them under a regime called CVCC which is constant voltage/constant current. Your charger will be set to charge the cells at a maximum of 4.20V per cell (or 8.4V for a 2-series battery. The remaining advice here assumes a 2-series battery).

It is advisable to limit the current to 1C (in your case 4A). Assuming your battery is discharged when you start the charger the charger will limit the current to 4A and you will notice that the charging voltage will steadily increase towards 8.4V. While the charge voltage is <8.4V you will see that the current is max'd out to the 4A value and this is the time when you are putting the most charge into your battery. Once 8.4V is reached the charger will hold that value and the current will start to taper down towards zero. Many people think that once 8.4V is reaches the cell is fully charged or 'peaked' because they are comparing the effect to NiCd or NiMH cells. This is not the case and the current should be allowed to taper down to at least 0.1C before the charge terminates. I don't know what current taper your charger uses and a charger may terminate any where between 0.1C and 0.025C. As the current is tapering you are putting less charge into the cell for any given unit of time.

Overall with LiPo cells:

*Never charge them over 4.2V/cell (8.4V for a 2-series battery)
*Charge using a LiPo charger that has a balance function.
*Use an ESC with a LiPo cut-off (or always stop your car before it runs slow)
*Never leave them in your car connected - even if the car is switched OFF.
*Charge them in a LiPo sack
*Store them 40-50% charged (my advice is to charge them before your race and then store them with the capacity that remains following your race).
*Stop using them if they swell.


N

[soane]

Thanks Neal for that advice, I use an Overlander charger and was watching it with baited breath as the voltage went up and current down (2-cell lipo). Happier now that I've read this

[jmke]

sorry for bumping this thread; didn't think my question required a new thread.

Originally Posted by neiloliver

Hope this helps...

thank you Neil, helped a lot, saved your post for future reference.

So charging at 1C is the "max allowed"; if your charger has max 5A rating, if you want to charge a 5400 mah LIPO, you can safely charge at a lower than 1C rating I presume? It would just take longer than charging at 1C ?

thank you in advance for your answer.

[Deano577]

Hello I have a 4000mah 20c what would be the charge setting.
Also what is 1c as mine is 20c?

[damselfly]

Originally Posted by Deano577

Hello I have a 4000mah 20c what would be the charge setting.
Also what is 1c as mine is 20c?

4000mah = 4 Amps, so charge at 4 Amps.
20c is your max discharge rate, so discharge at 20 x 4A = 80A maximum.