Quote from: saurabhhsrivastavaa on July 19, 2010, 02:20:57 PM
Some Useful information on Lipos...

https://sites.google.com/site/tjinguytech/charging-how-tos

Sorry for the duplicate post... i guess people have already posted this link...

Not creating a separate thread for this. I am a new user of lipos. See the images for a fully discharged and full charged 4S 5800mah lipo.

Please let me know if the cell voltages are fine for both. How much high and low can they ideally go when fully charged and full discharged?

Fully charged should be ideally 4.20v in each cell.  Note that slight discrepancies can arise out of less than perfect balancing, accuracy errors in the measuring device itself etc.

Discharged volts is a bit more flexible, keeping it around 3.3v per cell would work OK.

I follow the 80% discharge rule and end up with about 3.7V after discharge. Your pack is low comparatively.

Following the 80% discharge rule is best practice, but 3.7v after 80% discharge sounds high.   Should be more like 3.4v to 3.5v per cell, in my experience.

3.3v is more of a lower limit.  Note that most ESCs offer lipo cut off voltages around 3.0v.

Most of the mah the battery consumes during charging is above 3.70 volts. i will post a voltage/mah graph once Iam free.

So in my opinion 3.7 volts has < 20 % charge or approx 20% charge. From what I read from other sites. If discharged by only 80% all the time, then the cycle life can be doubled. But AFAIK, The battery gets destroyed in crashes by then atleast for me  .

My Turnigy and Flightmax 3000mAh packs end up at 3.7x or 3.6x worst case after 80% discharge. I got out of electrics long ago, so no recent experience with a variety of other packs.

I have kept auto lipo detect setting on my ESC which cuts off power at 3.0v per cell. Should I increase that?

Yes, it is best for the health of the lipo that you do not go that low. 

Ideally, the 80% rule is the way to decide how much you can routinely extract out of a lipo.  But I am not sure if this can be easily done in the case of electric cars, as you are constantly playing with throttle which makes it difficult to time the usage.  If you can follow the 80% rule (described as item [4] in the beginner post of this thread http://www.rcindia.org/batteries-and-chargers/taking-care-of-lipos/msg194/#msg194) for cars, that is what you should follow.

Quote from: anwar on September 22, 2010, 12:35:20 PM
Following the 80% discharge rule is best practice, but 3.7v after 80% discharge sounds high.   Should be more like 3.4v to 3.5v per cell, in my experience.

3.3v is more of a lower limit.  Note that most ESCs offer lipo cut off voltages around 3.0v.

depends on how much amp u pull from the battery but 3.7 sounds about right to me with new chemistry lipos do they hold volt much better. old lipos 3,4-5

i have 3.3V as default cut-off for car
i guess thats fine, pls correct if wrong..

 I see that below 3.65 Volts the cells already start going off balance on my flight max batteries.

Quote from: mail4ajo on September 22, 2010, 06:31:00 PM
I have kept auto lipo detect setting on my ESC which cuts off power at 3.0v per cell. Should I increase that?

a cell should never go under 3v under load, if u have the lvc to 3 volt it is 99.9% chance that your cells are out of balance and the lvc take a average volt mean that min 1 cell will be to low.

there is lipo warner that monitor each cell in the pack  instead of taking a average volt

Quote from: traxxrc1 on October 05, 2010, 09:38:20 PM
i have 3.3V as default cut-off for car
i guess thats fine, pls correct if wrong..

3,3 should b ok, but using it as a limiter and run until lvc kicks in your batteries will probably not last long,best is to get  some thing that monitors the cells individual  if u want to get max out of your batteries.
especially if u have high burst like on a heli

lipodimatic is a very god device to get max runtime out of your batteries

See image. Are the cells badly unbalanced? Is is ok to charge?

You can charge them back using a balance charger. 

Avoid draining this low next time around (stop flying/bashing/racing earlier, with more charge left in the cells).

Quote from: mail4ajo on October 18, 2010, 01:13:20 PM
See image. Are the cells badly unbalanced? Is is ok to charge?

u are killing your batteries.

new formula lipos hold volt very good and when u start to drop to 3,4-3,3 under load they are empty, allmost 0 left. when u have 3-1 3,4 with no load all your cells have been under 3 v under load, this is probably 1 of the best ways to make sure the battery would not survive for long and give u crap performance

Quote from: anwar on October 18, 2010, 03:20:52 PM
You can charge them back using a balance charger. 

Avoid draining this low next time around (stop flying/bashing/racing earlier, with more charge left in the cells).

So its safe to charge, right? I will set my ESC cutoff at 3.4V/cell. Its 3V/cell now, default by ESC. Will that work or better to set at 3.7V?

How low per cell is seriously bad?

I dont think 3V is good... I preffer 3.2V. even 0.01V matters.

Lipos tend to last longer if the 80% rule is followed.  The newer lipos end up with 20% of charge left when the voltage comes down to 3.7v per cell (per Vinay/Rotorzone/others... I did not test this again recently with newer packs).  So it would be a good idea to stop using them at 3.7V per cell.

Below 3 volts is pretty bad, and further down it gets significantly worse.

the lvc is not a safe way to manage the lipos. if u want to use the batteries to the max u need a lipodimatic to monitor watch cell in the pack. they are cheap and work very well

Quote from: clayboy on October 18, 2010, 08:46:42 PM
u need a lipodimatic to monitor watch cell in the pack. they are cheap and work very well

Where or how can I get one? Where can I read more on this device?

I send u a pm when I get back home

This should help !

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=15237