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Old Apr 17, 2012, 09:18 PM
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Conditioning new LiPo batteries?

I'm sure this information is located somewhere in the forums but I can't find it.
Is there a guide on how to condition new LiPo batteries somewhere?
I remember reading that you're not supposed to run them too low for the first few flights. Should the maximum charge also be limited for the first few flights?
I have a new v911 that I just received so it has a very simple, automatic charger.
I can use a voltmeter to measure the charge if necessary
A link to whatever information is available would be very helpful.
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Old Apr 18, 2012, 12:49 AM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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NEVER run a lipo too low. Just once can kill its capacity. "Too low" is using more than 80-85% of its mAh rating.

No (proper) charger I know of can overcharge a lipo. You can always charge all the way.

It is recommended that for the first 5 discharge cycles you only run it down half way.

I always wait 20 minutes after use to recharge. The battery should be cold/room temp.
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Old Apr 18, 2012, 12:14 PM
Team Wack-a-Mole
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Joined Oct 2008
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Here is some basic reading
http://www.mycoolrc.com/LiPoInfo.html
Unlike NiMh and NiCd, you can't "cycle them back into good health".
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Old Apr 18, 2012, 12:14 PM
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Joined Mar 2012
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Thanks for the info.
Is there any way to measure % capacity remaining based on voltage?
I'm not sure how to judge how much current I've used although it's simple enough to time my flights.
I know a single cell should max out at ~ 4.2V fully charged and that they should never be run below ~ 3.3V.
Is it linear? For example, does 50% remaining capacity measure 3.7 - 3.8 volts?
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Old Apr 18, 2012, 12:55 PM
Fly Runaway Fans
United States, TX, Fort Worth
Joined Jan 2009
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Voltage mostly only tells you limits.

A computing charger will tell you how many mAh went back into it which is how much you used.

A 1C charger should take about 48 minutes to replace 80% of capacity but this isn't a hard figure because some chargers reduce rate for the latter half so it's no longer 1C.
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Old Apr 18, 2012, 01:42 PM
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+1 on using a computer charger and keeping track of what you put back into it. That's the best way to get experiance with your battery as well as how your flight times and flying style affect usage.

Lipo Capacity is somewhat tracable to resting voltage but each cell chemistry will be different. You'd have to test it individually and make sure it is unloaded because with Internal Resistance, load voltage changes from resting voltage. More so with a worn down battery.

I know with most of my Gens Ace batteries, 3.85V per cell is about 40-50% depleted.

This is an old chart and probably may not be current with most of the modern LiPos but you can take a look.
http://www.mycoolrc.com/FILES/LipoVoltage.pdf
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Old Apr 18, 2012, 02:07 PM
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Joined Feb 2012
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Using the "80% Rule":
A 2200mAH Li-Po, discharged to 80%, SHOULD- when charged- put back ~1760mAH.....
Newer generation Li-Po's CAN be charged UP TO 5C....BUT....I find it's best to still charge at ~2C, tops....especially NEW batteries......after 20-25 cycles, TRY a 3-5C charge ONCE....and check on: 1.) current put back ("80% Rule"....) 2.) voltage per cell (~4.2v/cell) and 3.) battery temp.....is it warm to the touch...or "too hot to handle"????
If ANY one of these 3 criteria aren't met...I'd revert to 1-2C charge rate.....
Just my opinion...YMMV!!
Good Luck!
Happy Flying!
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Old Apr 18, 2012, 02:24 PM
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I used a pair of Nanotechs (max charge 5C) for combat. I had to charge them back up (depleted 60% on average) in 10 mins. I charged at 4C and I can attest that they did not last as long (the IR increased) as the ones I took it easy on. Yea, the pack may say max charge rate, but you will pay for that over time is what I found at least with the nanotechs as well as the Gens Ace. Buddy has a Hyperion and he attested to the same thing.
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Old Apr 18, 2012, 05:27 PM
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Quote:
Originally Posted by chenz759 View Post
Thanks for the info.
Is there any way to measure % capacity remaining based on voltage?
I'm not sure how to judge how much current I've used although it's simple enough to time my flights.
I know a single cell should max out at ~ 4.2V fully charged and that they should never be run below ~ 3.3V.
Is it linear? For example, does 50% remaining capacity measure 3.7 - 3.8 volts?
Voltage drop is not linear and the best way to tell exactly how much you are using is to have a charger that tells you how much Mah you put back in.

In the absence of this, you can however be comfortable that you are at roughly 80% capacity used if the battery has about 3.7Vper cell resting voltage after use. It's not a perfect way of doing things, but it will keep you from ruining the packs. Remember you are measuring the voltage with no load on the battery. The voltage is lower in the heli under load.
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Old Apr 19, 2012, 09:10 PM
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Joined Mar 2012
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Thanks.
Since I'll be making limited time flights to break the batteries in, I'll measure the no load voltage after each flight to get a sense of how long it takes to get to ~ 3.7 volts or 80% discharged.
I'm only flying a v911 so it uses single cell, low capacity batteries and came with a simple automatic charger.
The upside is the batteries are available and cheap so it's not really a huge deal.
I'm just trying to learn more about it as I teach myself to fly.
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Old Apr 19, 2012, 10:38 PM
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Quote:
Originally Posted by chenz759 View Post
Thanks.
Since I'll be making limited time flights to break the batteries in, I'll measure the no load voltage after each flight to get a sense of how long it takes to get to ~ 3.7 volts or 80% discharged.
I'm only flying a v911 so it uses single cell, low capacity batteries and came with a simple automatic charger.
The upside is the batteries are available and cheap so it's not really a huge deal.
I'm just trying to learn more about it as I teach myself to fly.
That's the tricky part since the voltage drop won't be linear over time and you cant assume because one minute of fight dropped the voltage "X" that the next minute will do the same. You could be at one voltage 3 minutes into flight and dump 30 seconds later depending on the condition of the battery. You should be able to get a reasonable idea of how many minutes of flight will get you into the zone though with some experimentation.

Once you move up into bigger helis, the Mah method will serve you much better and is much easier to calculate since its more linear. I know for example, that my T Rex 500 uses about 230 Mah per minute and I don't want to use more than 2100 Mah of my 2650 pack. This is easy to determine with a charger that shows how much I'm putting back in with a couple minute test flight on a full pack. 9 minutes puts me on the edge, so I have my timer set to 8 minutes to give me padding and time to land without pushing the batts too far.

Good luck!
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Old Apr 19, 2012, 10:53 PM
V120D02S, GCP
LarsDennert's Avatar
United States, CA, Pasadena
Joined Feb 2012
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My GCP seems to loose power when the cells are at 3.8V. Sounds like this is normal then. Thanks for the info.
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