adam crosby

How long should I be able to use a 1000mAh LiPo? I have had it for 3 months and use it twice a day but it seems to be losing power. Is this normal?
Thanks
Adam

HeliTB

If you are over discharging the battery. The life of a lipo can be long if the cell are balance and care for properly. But over time the capacity will diminish.

mrasmm

Most good quality lipo's are rated for something like 800 cycles. That's a flight a day for 3 years =). Most die before that because of abuse or poor manufacturing. Over heating, improper charging, over draining, improper conditioning, not a high enough C rating, ect ect.

I have found a way to sometimes get them to come back a bit is to fly half of your normal flight time and put them on the charger (of course wait till they come down to room temp, or about 80F), and repeat this 5 or 6 times. It has worked for me to get my batteries that are sloping off to perform a bit better.

credence

My Feedback: (2)

800 is highly optimistic and only applies if you're seriously under-using your battery (i.e drawing at 1C rates or less). At the rates we use our packs at, 500 cycles or less is more in the right area.

I believe at around 350 - 400 cycles under normal use you'll see about a 20% capacity drop off, and then it'll continue to deteriorate after that.


If you really push your packs to their max rated discharge, you'll likely only see 50 cycles before getting noticeable capacity loss.

Quality of the battery and how you treat it also has an impact on lithium life. Not all cells are created equal.

Basically, there is no solid answer to lithium cell life because theres simply too many variables, if you want a general estimation though, assuming you are not abusing the packs and your cells of are atleast moderate quality, id say you should see expect to see somewhere between 200 to 300 cycles.

Some tips to prolong cell life ->

Keep pack temperatures as low as possible. In other words, don't drain power from the battery at a fast enough rate to cause excessive heat build up.

When discharging your batteries, discharge to about 80% of capacity and then end the flight. The lower you drain the pack per flight the shorter the overall life will end up being.

When charging the battery, lower rates are better than higher ones. Charging at a 1/2C rate is better for the packs life than charging at a 1C or even 2C rate.

Avoid physically denting the cells as this usually results in immediate capacity loss.

When storing your batteries, store them in a 50% charged state in a cool, dry area.

Maintain cell balance over the batteries life (use a balance charger to charge the pack).

andyroxs

on the topic of recharging LiPos, can anyone tell me how to store them? After im done using it, am i supposd to put it away w/o power left inside?

andyroxs

oh haha im so dumb, didnt see that credence already answered my question. Sorry

mrasmm

if you have a good discharger charge the pack all the way up, and note how much you put in. Take out about 50 to 70% of the juice. So, if you put in 950mAh then take out about 600mAh. Alternately you can just discharge it to about 3.8v per cell.

DebianDog

The reality of "Hard 3D" on a helicopter on 20C packs is more like 200-300 flights. -I think- it will be more once we start seeing the 25C packs being the packs will more readily give up their electrons.

credence

My Feedback: (2)

In my experience, the biggest killer on cycle life is draw rates and heat buildup (the two are often linked).

It does not matter who makes your battery and how good it's quality is, if you're always pulling your pack down at true 20C rates, you won't see a long cycle life. 200 cycles at 20C would actually be pretty good. Most guys don't seem to get past 150 from what i've seen, but other factors (such as user negligence) come in as well so that may have an effect on the outcome.

If you take two batteries from the same mfg and same capacity, and both are rated for 20C discharge, and if you discharged one at 10C constantly and one at 20C, it's a good chance the one discharged at 10C rates will last quite a bit longer.

Debian is right though, once we start seeing 25C and even 30C packs (as the manufacturers claim, we'll see..) cycle life should go up quite a bit.


As far as lipos go, if used within or below spec, the average (theoretical, anyways) life cycle is 500. However, the way we use our packs usually results in much, much less..

DebianDog

Flight Power has many of their pilots testing the new 25C packs and (I have been told) they are almost cool to the touch after flying them. I problem (I hear) is that since the packs are able to deliver this energy rather easily the new packs are hard on the gears and frames of whatever type helicopter you put it in. So just be aware you may be able to dial it down a bit and get the same performance with 25C packs.

credence

My Feedback: (2)

Well that's probably the general idea now with these new packs. With more power on command because of the better delivery, the idea is not to make the helicopters power output more ballistic, but to make it more efficient. That will likely require some toning down of the throttle or pitch curves when going to high rated discharge packs. But at the same time, should provide the same power we're used to now at much reduced stress on the battery.