lololover_

Hello !!!

Im a newby on the Forum !!! So hello everybody !!!

All is on the Subject !!!

Im on the right way ? It is 3v per cell the minimum discharge right ? So i use a 3cell 2100mHa thunder power 11.1V
So ill put 9.3V on the setting in my charger. It is good ???

Thank you !!!

guver

My Feedback: (325)

I am kinda new to lipo, but it seems rather debateable right now . The LCV for discharge seem to be from 3 volts / cell to 3.3

The minimum open voltage seems to be from 3-3.7 volts / cell. I am using resting voltage of 3.7 and diacharge of 3 and consider the 3 volts / cell to be too low even though both of my manufacturers recommended it.

lololover_

So,

What can i do ? Ask to Thunder power ???

Anybody here use the same Accu then mine ???? Please i need help !! Can't fly my Typhoon 3D till i have response !!!

Thank you

Matt Kirsch

My Feedback: (21)

3.0 Volts per cell, at rest, is the RECOMMENDED minimum voltage, pretty much industry-wide. There is very little energy left in the cell, maybe a few percent of total, at this voltage so there is little point in drawing it down further.

3.7 Volts is the nominal voltage of a LiPoly cell. Fully charged they should read 4.2 Volts.

I am not sure where people are getting the idea that 3.0 is too low, or even that 3.7 is the minimum voltage??? At 3.7V the battery pack still has about 50% of its usable capacity left.

Are you discharging your cells on a charger? Why? There is only one reason to discharge a LiPoly cell, and that's to check capacity if you feel that there is a problem. New LiPoly cells do not need any special breakin or cycling. Just charge and go flying.

9.3 Volts would be a suitable cutoff setting to discharge the pack, though once the load is removed, you'll probably find that it bounces back a few tenths.

guver

My Feedback: (325)

I am sure we agree on the first two points (recommended minimum and the nominal voltage)

The 3.7 figure is an open voltage that I am getting from the electric fliers who are posting discharge graphs. I am still debating on whether to use 3.5, 3.6 or 3.7 for a minimum open voltage, but can assure that at 3.7 there is not much useable energy left. I am showing 0-30% yet going much lower quickly approaches the zone of danger in overdischargeing. Perhaps I am more conservative from being a bit new to lipos yet. (I normally push the limits of all things rc)

I can definately agree also that there is no need to discharge, and have also seen the recommendations to use a few gentle cycles to break-in the pack, maybe check balance to be sure.

If using a 9.3 (3.1) lcv then the voltage will as you say spring back up to a higher resting voltage. This far higher than 3 volts and depending upon the discharge rate it can be close to the 3.5-3.7

lololover_

Hello,


Thank you for your help ! im a newbie in LI-PO ! Thank you for tell me that there is no reason for discharging a lipo battery. Ok, ill only charge and fly !!! :-) with a little break before charge after flying !

Really , a BIG thank you !!!!

See you !

guver

My Feedback: (325)

Seems we have a bit of difference of opinion, and glad that we helped you. Pretty much watch the voltages of the cells and do whatever it takes to stay between 4.2 and (3.7-3.5) or 3 volts according to Matt. If I get a chance I'll look into it more , I notice that on the discharge graphs there is nearly a straight line down after the knee of the curve indicating a quick voltage drop relative to capacity. I am new to it also. Trying to get rid of nickle batts,,,

lololover_

Ok thank you, but now that i know that i have no reason to discharge my LI-PO, ill never do that.. ( i see yesterday that my charger can adjust only the V discharge at : 3v - 6v - 9v - 12v - 15v So, i can't put 9,3v like i said.... Doesn't matter.. No more discharging now !!! ;-)

Sorry for my fault maybe, i never learn English at school, only internet girls friends.... i come from Swiss french part.

Thanks Alot !

Matt Kirsch

My Feedback: (21)

At 3 Volts per cell you've squeezed just about every usable drop out of the battery, and are still well above the "drop dead" voltage of 2.5 Volts per cell, and the "hurts so good" voltage of 2.8 Volts per cell. It's been the conventional cutoff voltage for nearly the entire time I've been involved with LiPolys.

Now, I'm not sure about the discharge graphs you've seen, but the ones posted by RC-Tester generally have a long, relatively flat section that signifies the bulk of the discharge. Depending on how hard they're pushing the packs, the voltage is somewhere between 3.8 and 3.4 Volts. Note that that is a constant discharge. Under varying discharge, you'll see a bounce, and a generally higher voltage.

guver

My Feedback: (325)

Ya, I think that perhaps the most important distinction is to label the voltage and not to confuse "open/resting" voltage with voltage during use/discharge.