[NSRCA-discussion] LiFe batteries

[John Fuqua]

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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