[NSRCA-discussion] Battery Resistance

[Ron Hansen]

I'm running a Hacker Q60, HV80 ESC, and 21x 14 prop.

 

The motor quickly reaches 5900+ rpm but quickly drops to 5700-5800 or less
after a few seconds.

 

I tried a Jeti Mezon with similar results.

 

I tried a new Himax with similar results.

 

Only think left is the batteries.

 

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On
Behalf Of Chris Moon via NSRCA-discussion
Sent: Sunday, June 07, 2015 11:12 AM
To: Stuart Chale; General pattern discussion
Subject: Re: [NSRCA-discussion] Battery Resistance

 

IR numbers of 6-7 per cell mean the packs are pretty much done for our
purposes.  A good new 25C pack should have IR numbers around 2-3 and a 35C
pack around 1.8-2.2 or so.  Essentially with an IR of 6 you have a battery
that will perform like a 10C or 15C battery which will limit the top power
output and will run hotter doing so.

Chris

On 6/7/2015 11:04 AM, Stuart Chale via NSRCA-discussion wrote:

2 possibilities.
1) packs are worn out replace and fly  (most likely)
2) Motor is messed up rotor demagnetized if Neu or Hacker etc.  Generally
current is much higher than expected and hotter after a flight.  

If you fly with another pattern pilot with similar battery setup/connectors
you could always borrow a good battery for a flight.

On 6/7/2015 10:55 AM, Ron Hansen via NSRCA-discussion wrote:

The packs are less than adequate on some or most of the advanced maneuvers.

 

They are also getting more and more difficult to charge to close to 100%.
Actually I can't really get then to 98%.

 

From: atwooddon at aol.com [mailto:atwooddon at aol.com] 
Sent: Sunday, June 07, 2015 10:35 AM
To: rcpilot at wowway.com; nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Battery Resistance

 

Ron, what is the pack temperature when you are measuring the resistance?
Temperature has a big impact on the measurement.

Also, how are you measuring the resistance?  

If those are the resistance values (6 per cell) at 70F measured with an
iCharger, FMA charger or Giles dedicated meter, then the pack is starting to
get 'tired'.  However, if they get you thru your sequence and isn't too hot
at the end, go ahead and use them until they don't perform adequately.

Another thing that can kinda sneak up on you is lipo packs gradually loose
capacity over time.  If you fly the same sequence each time and the voltage
at the end gets lower and lower, the packs are probably loosing total
capacity.

Don

 

 

 

-----Original Message-----
From: Ron Hansen via NSRCA-discussion <nsrca-discussion at lists.nsrca.org>
To: NSCRA Discussion List <nsrca-discussion at lists.nsrca.org>
Sent: Sun, Jun 7, 2015 7:24 am
Subject: [NSRCA-discussion] Battery Resistance

How do I know when it is time to replace my batteries.

 

The total resistance in my 5 cell Zippy Compacts is 30 - 33 milli ohms
(about 6 per cell).

 

Thanks



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