Stick 40

I did a search on cycling lipo battery's and found nothing.

does anyone cycle lipo's to check on Mah capacity. There must be a way to check on capacity .

sticks

guver

My Feedback: (325)

Some of us will run a discharge cycle to check capacity , but since the charging of lipos is near 100% efficient the displayed capacity on a charge cycle is usually "good enough" to verify capacity. Balancing will make the number go higher depending upon how it is done.

Stick 40

ok, I have been getting into capacity with some my battery's and wondering about Lipo's.

If you discharge down to get a capacity of a lipo, what voltage to you go to.

sticks

guver

My Feedback: (325)

If I understand you properly you're asking what voltage is 100% of capacity? I'm not sure what the spec is. Many of mine have been about 3.5 volts (RESTING) when new. Some are labeled high or low though for various reasons. I label my packs for actual capacity between 3.7 and 4.2 exactly and that is never what the label is , but I don't really care. I just need to know the actual capacity.

jetmech05

It is my understanding that you don't need to cycle Lipos.....I use LiIons myself...I am regulated to 6v and recharge at 7 volts on a 1 amp load.
I can go 2 or 3 weeks between charges flying 3 or 4 flights a weekend. hope this helps you

jester_s1

Lipos don't have a memory effect, but all batteries should be cycled occasionally to test capacity. When the internals start to break down, you get a loss of capacity or a reduction in voltage under load. Testing lipos for capacity and also real world amp draw on your plane is a foolproof way to catch a battery that's going bad before it costs you a plane.

3v per cell is the lowest safe discharge, although full capacity is more like 2.5v. A discharge to 3v won't give you the rated capacity of the pack, but it will show you what I call the "working capacity" which is the maximum safe discharge in flight. I then time my flights to use less than 80% of the working capacity for the best battery life.

Stick 40

yes, your answers are what I am looking for.

I bought a elect plane from a friend and the thunder power Lipo is 3 years old. He did not feel that you could cycle a lipo to check on remaining capacity.

I see mine as being run between 3.7 v to 4.2v per cell, that is I don't want to go below 3.7v on a flight.

I would think I should cycle down below 3.7 to see if there is still capacity left for safe flying?

Just went back and read Jester, so 3v is a safe and effective level to go to?

thanks
sticks

guver

My Feedback: (325)

Make sure you make a distinction between loaded voltage and resting voltage. Resting voltage is the only reliable indicator of remaining charge for ALL packs. Using a loaded voltage is a moving target as it relates to remaining capacity. The figures for open voltage is exactly as you stated 4.2 - 3.7 with a tiny bit of capacity down to 3.6 and 3.5. There IS capacity down there below , but you are operating over the "knee of the graph" and if it's power packs your working with then there's almost NO useable capacity below 3.6 volts. If it's radio batts then there is useable capacity down lower , but you may not want to take the chance of running out and/or damaging the battery by using it too low.

I'm a stickler for wanting to use all of my capacity up , yet never using more than I should. I like to wind up with exactly 11 volts on my 3s packs. My last OOPS was a flight that was far more aggressive than normal and even before the timer went off I felt and heard a noticeable drop in power. I immediately dead-sticked in and the pack was at about 10 volts. This is way below what is normal for me since I set my timers to land at 11 volts. I should've known better , but just didn't quite pay attention that I was hammering it for 23 minutes. My timer is set to 27 minutes. I knew exactly what happened as soon as it happened and is not normal for me. I haven't felt a LVC in over 1 year.

Stick 40

what about a discharge to the 50 % storage level.

on a 2600 Mah pack 3 cell, would that tell if the pack has good capicity? If I get abou 1200 Mah at storage level, is that a good indication that the pack is still good?

sticks

guver

My Feedback: (325)

Yes, probably. You'd have to have previous knowledge of the exact actual capacity to get any closer accuracy than that.

Stick 40

I went ahead and charged the 3 cell 2600 Mah lipo pack, its 3 years old.

I then discharged it in 50% storage mode and got 950 Mah.

don't know what that means. I am going to charge one of my new ones and do the same thing. I will charge and then discharge to 3v first, and then do the 50% storage.

don't know if I will get it done real soon.

sticks

Stick 40

I really wonder about the idea of resting voltage readings, I have found that a resting battery will move up in voltage readings.

I call it phantom voltage, are lipo's different in this regard?

sticks

guver

My Feedback: (325)

After use they will move UP. After charging they will move DOWN.

acdii

Full charge 4.2 V per cell, storage 3.8 V per cell, cut off 3.0V per cell.  Lipos also have a life span, so discharging to check capacity reduces the number of times you can use it.

Simple rule of thumb I use, Run the pack in the plane until the ESC cuts out, time it, land, and recharge. Now you know how much charge is in the pack.

A good charger is a must too.

Stick 40

so the esc will cut out and let you land?

sticks

Stick 40

that is what I am getting at.

a battery that has been run down, will come backup and show a higher voltage and that is the phantom voltage that is not really there.

A battery that is charged to peek will come down, I would guess that the voltage it comes down to is close to useable condition voltage.

jester_s1

The 3.0v cutoff would be a voltage under load test. My Triton EQ defaults to that for testing a lipo. I haven't checked to see what the resting voltage is when it's at that level, but I'm sure it's a little more. My batteries give me about 80% of their rated capacity at that 3v cutoff, so that's my baseline from that point forward for evaluating those batteries. For lipos though in my limited experience, the first thing to go is their internal resistance, which means that your full throttle power is reduced. I knew it was time to replace the batteries in my Stryker when I went from 19700 rpm to 17100 rpm at full throttle on the same batteries. They still capacity tested fine and weren't puffed at all. 3 years is the point where you need to keep an eye on a good battery because lipos break down internally over time even if they aren't used a lot. If your capacity test is around 80% and the plane has enough power to suit you, I'd say your battery is still good.

Stick 40

that sounds good.

The guy I got the plane and battery said he does not check them, maybe what you are saying is what he is doing.

He is one of our best elect flyer and only flys elect planes , I will have to talke to him more and see what he says.

thanks

sticks

Stick 40

that sounds good.

The guy I got the plane and battery said he does not check them, maybe what you are saying is what he is doing.

He is one of our best elect flyer and only flys elect planes , I will have to talke to him more and see what he says.

thanks

sticks