[NSRCA-discussion] LiFe batteries

[Ihncheol Park]

Mike,
What is the fully charged voltage on the pack?
at 3.3v your packs is about 35% charged.

A123 cells have 3.6V maximum
Hobbico LiFe packs and a lot of others have 3.7v maximum.
My TP820 charges them to 7.4v.
You need to check the final voltages & cell resistance of each cell.


Ihncheol
 

________________________________
 From: "Dr. Michael Harrison, DDS via NSRCA-discussion" <nsrca-discussion at lists.nsrca.org>
To: 'John Fuqua' <johnfuqua at embarqmail.com>; 'General pattern discussion' <nsrca-discussion at lists.nsrca.org> 
Sent: Friday, October 10, 2014 9:05 AM
Subject: Re: [NSRCA-discussion] LiFe batteries
  


Same with me.  I did all those things last night.
mike
 


From:NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John Fuqua via NSRCA-discussion
Sent: Thursday, October 09, 2014 7:30 PM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] LiFe batteries
 
Very Interesting.   I have 3 850mah LiFe 2S batteries I use.    I just charged all three and right at the end of the charge cycle, monitoring cell voltage, one cell went high.   About 2 tenths of a volt or so.   So I balanced them on my balancer.    Recharged.  Same result.   Then I put them on discharge.   The closer they got to 6.6 volts the closer the cells got to 3.3.   maybe 3.31 and 3.29 worst case.   it seems with these batteries there will be some voltage difference at fully charged.   Now I wonder if this is a characteristic of the LiFe battery or the Cheetah brand???????
 
 
From:Ihncheol Park [mailto:pnahobbies at sbcglobal.net] 
Sent: Thursday, October 09, 2014 5:28 PM
To: John Fuqua; 'General pattern discussion'; General pattern discussion
Subject: Re: [NSRCA-discussion] LiFe batteries
 
I use LiFe on a few glow models and have a few other friends using LiFe on gas models.  Engines are hard mounted.  
depending on the size, about 100 to 300 mAh are used.  Largest being a 30cc on a giant scale stik with 7 high torque digital servos.
 
Best way to check is using something similar to Hyperion Sentry.  it shows capacity based on the pack voltage on LiXX type.
It is pretty close to actual.  about 2 to 5% variance.
 
 
I am using Team Orion LiFe RX packs have up to 35C rating.  Hobbico is 10C rated.
 
Minimum voltage is 3.0v per cell, so 6.0v  I wouldn't fly if the pack is 3.2v per cell.  I've never had a chance to fly/discharge the rx pack down close to minimum voltage.   usually stop flying, charge, or replace the rx pack if the pack has about 30% left.
Discharge curve is similar to LiPo.  Flat and drop sharp.  
 
Hope Mike is using a charger that shows mAh charge amount.  much easier to calculate how much capacity is used per flight.
 
Ihncheol
 
 
From:John Fuqua via NSRCA-discussion <nsrca-discussion at lists.nsrca.org>
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org> 
Sent: Thursday, October 9, 2014 4:48 PM
Subject: [NSRCA-discussion] LiFe batteries
 
Mike Harrison asked a question about LIFE batteries that I don’t know the answer to but I am sure there are experts out there that do.     Mike has switched to 1750 LIFE batteries in his YS powered airplane.   So how many mah average would one expect to use per flight?    What does the discharge curve look like and what is the cut off voltage below which you quit flying???
 
I run LIFEs in my electric and I consume about 60-70 mils per flight average but do not have a clue as to a 4 stroke powered plane.    
 
Thanks 
 
John D. Fuqua
johnfuqua at embarqmail.com
850-974-6655 Cell
 

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