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e-Electric General Discussion > Anybody have a chart on Lipo's and voltage cell percentages ??
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

My Posts This: Topic  Forum		Start with a basic :

Say Individual cell charged and discharged

Cell counts 1S - 2S - 3-S ect



Cell multiple voltages Highs and Lows

Then a cross reference showing pack % in capacity and related voltage.

Sure help in watching the 80% rule

No Hit's ? OK " try this " on a 3S pack what is the STOP VOLTAGE

For ref : 1S Data

100% charge = 4.20 volts
76% charge = 4.02 volts
62% charge = 3.86 volts
43% charge = 3.83 volts
30% charge = 3.79 volts / Storage ???
11% charge = 3.70 volts
0 % charge = 3.6? volts




I'll try to edit this same post as the numbers come in till it's sifted out a bit

greyeagle
11-02-2009 04:54 AM
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Wingman77
Elite Veteran
Location: Pulaski TN US

My Posts This: Topic  Forum		don't ever run a lipo below 3.7 a cell.
11-03-2009 04:11 PM
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Heli 770
rrProfessor
Location: Lemon Grove, Ca. USA.

My Posts This: Topic  Forum		This is what I use.

100% 4.20 volts
90% 4.15
80% 4.10
70% 4.05
60% 4.00
50% 3.95
40% 3.90
30% 3.85
20% 3.80
10% 3.70
11-03-2009 04:32 PM
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GREYEAGLE
Key Veteran
Location: Sioux City IA

My Posts This: Topic  Forum		Thanx for your number 's 770

Much appreciated ! Well done, Thanx : Cut Copy Print !

greyeagle
11-04-2009 02:04 AM
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MrMel
rrProfessor
Location: Lidingo, Sweden (GMT+1)

My Posts This: Topic  Forum		It totally depends on C-rating, IR of the pack.

3.85v is considered "around" 50%

My Hyperion G3 VX is around 3.89 for 60%.
(talking resting voltage here)

My site: http://heli.dacsa.net
11-04-2009 12:51 PM
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Terrabit
Key Veteran
Location: Seattle, WA - USA

My Posts This: Topic  Forum		It's important to note that even if your lipos settle at or read 3.7 after flight it is very likely that cells experienced much lower voltages during flight. I aim for an after flight resting pack voltage of 3.75/cell or higher.

Are you attempting to setup a voltage cutoff?

Esprit Model Flight Team
11-04-2009 08:07 PM
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GREYEAGLE
Key Veteran
Location: Sioux City IA

My Posts This: Topic  Forum		Wish I could set a LV warning

Just getting into the science of Lipo's - looking for some basic preventive maintenance spec's to prevent damage - before I spend the $$$.
Not sure of the OEM BEC/ SC " Align 35 A has " preset safety limits.

greyeagle
11-06-2009 12:42 AM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum		Great Topic and precisely what I have been looking for.
Can we get more people to chime in please?

2 charts posted are not way off from each other but saying 3.85 has %50 capacity, does conflict with both of the charts...

Has anybody done a test with an actual lipo cell?
11-16-2009 05:29 AM
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helicraze
Elite Veteran
Location: Victoria - Australia

My Posts This: Topic  Forum		Different lipos and different conditions= no chart will give you exact.

Time your flights and check MA put back in. Better to discharge less than more. I time for worst case if i fly very hard then its no problem.
11-16-2009 07:10 AM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum		I do understand there is NO exact chart for this. All lipos are slightly different and this may depend on the application but one chart says 3.95volts for 50% and another person says 3.85volts.
It may seem small but there is a BIG difference between 3.85votls and 3.95volts. That's why I asked...

I myself have been doing tests and I am getting all confused.

For example: 6s 3300mAh lipo pack(almost new; has 3 cycles only)
After the flight, I measure around 3.79-3.80volts per cell and I can only put back 1700mAh (where I expect to put around 2500mAh back) This does NOT sound normal to me. Does it to you?
11-16-2009 03:18 PM
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MrMel
rrProfessor
Location: Lidingo, Sweden (GMT+1)

My Posts This: Topic  Forum		I have _never_ seen a lipo which follow Heli 770's chart, I think he's refering to cutoff voltages under certain load, not resting voltage..

Only way to tell is to do a controlled discharge to 3.2-3.3v and see how much capacity you have left.

(3.2-3.3v discharge for all >25C packs), do not discharge to 3.0.

My site: http://heli.dacsa.net
11-16-2009 03:20 PM
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Heli 770
rrProfessor
Location: Lemon Grove, Ca. USA.

My Posts This: Topic  Forum		The chart I posted was made over 3 years ago. Lipos have come a long ways since than. If your batt pack has lost capacity you will get all of the voltage reading as the chart, but it won't tell you anything about the capacity you've lost only what is usable in the batt pack. The only accurate way to check capacity is monitoring the mah you're putting back in the pack when charging. So only use the chart as a guideline.
11-16-2009 03:54 PM
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MrMel
rrProfessor
Location: Lidingo, Sweden (GMT+1)

My Posts This: Topic  Forum		yeah, lots have happened with lipos in 3 years

Here is another graph or resting voltages.
http://www.rcgroups.com/forums/atta...29&d=1230902392

My site: http://heli.dacsa.net
11-16-2009 03:58 PM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum		MrMel,

I would be willing to do a controlled discharge on one of my packs. It is a TP 4000mAh Prolite series pack with 12C rating.
I will fully charge it and then what discharge condition (load, cut off voltage etc.) would you use to discharge and test the capacity?

Thanks
11-16-2009 05:09 PM
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MrMel
rrProfessor
Location: Lidingo, Sweden (GMT+1)

My Posts This: Topic  Forum		For those packs (older packs) use 3.0v as cutoff, use the charger to discharge,max 1C for capacity check, or 0.5C for more exact.
But most likely it will be even less since most chargers are limited around 50watt discharge.
Make sure to have balancer connected in case some cells are bad (they will then drop faster)

My site: http://heli.dacsa.net
11-16-2009 05:14 PM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum		Yeah, I really do not think I can even do 0.5C. It will probably be no more than 1.0A or maybe just 0.5A.
I will definitely keep the balancer connected.
11-16-2009 09:18 PM
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MrMel
rrProfessor
Location: Lidingo, Sweden (GMT+1)

My Posts This: Topic  Forum		Just as a sidenote;

It seems that end-of-2009's lipos (like Hyperion, TP45C etc), when they degrade the voltage is still high, so you loose capacity while the power is still there, compared to older packs where the IR of the pack raised over time/after much use and voltage started to sag as well as capacity loss.

Meaning, with these packs today you have to cycle them to know how much capacity is left really if you dont want to end up doing 100% discharges.

So every year/generation there is a new beast to tackle.

My site: http://heli.dacsa.net
11-16-2009 09:31 PM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum		I just checked and my 1010P does NOT go above 0.50A for discharge when picked 10S pack. Given with the 4000mAh capacity, this discharge will take over 7 hours...
I gotta find a smaller pack to do this test... Plus I do not believe a pack will deliver the same capacity when discharged at much higher rate than 0.50A. But I would like to do the test anyways...
11-17-2009 04:09 AM
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JuanRodriguez
Elite Veteran
Location: Rochester, New York

My Posts This: Topic  Forum
Quote 
I just checked and my 1010P does NOT go above 0.50A for discharge when picked 10S pack

Why not "fool" the charger by setting it to a cell count that will allow you the discharge rate you are after..... IMO, it's just a discharge to a given "set" voltage at a "set" discharge rate and then the charger will shut off. The charger is not going to "know" what type of battery or cell count is attached to it and IMO, it does not matter....What you're after are the readings after the discharge cycle......Not being familiar with the 1010, it may not let you "manipulate" things in this fashion ??

A couple of us locally have the FMA 10S charger which (unfortunately) does not have discharging capabilities....To "circumvent" the issue, we use our Triton's to discharge our lipos if need be.....

Also, I would not recommend using the method above IF you cannot set your charger to do a discharge cycle ONLY. In other words, don't use a program that discharges and then automatically charges for this exercise....

I'm by no means an expert in this are and so I'll let the gurus chime in.......
11-17-2009 02:13 PM
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iskoos
Key Veteran
Location: Orlando, FL

My Posts This: Topic  Forum
Quote 
Why not "fool" the charger by setting it to a cell count that will allow you the discharge rate you are after.....

I do not know any way to fool the TP 1010C charger. It is not about fooling it. It is the capacity of the charger. It will do higher discharge rate with low cell count of course. It is related to total wattage. With 10s pack, 0.50A is the most you can get. It is not about fooling it or not...

I do not intent to use programmed cycle(charge/discharge)
I will manually charge and then manually discharge to see what(nominally) I can pull from the pack...
Like I said above, I will use smaller pack to do this test...
11-17-2009 04:32 PM
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e-Electric General Discussion > Anybody have a chart on Lipo's and voltage cell percentages ??
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