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Old Nov 08, 2012, 11:05 AM
I think I'm inverted. Maybe.
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United States, CA, Pacifica
Joined Apr 2012
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Quote:
Originally Posted by Miami Mike View Post
By the way, your idea of installing a speaker in a model so that you can broadcast sound through it is interesting. I'll bet you could cause a lot of trouble with something like that.

http://www.mrrcsound.com
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Old Nov 08, 2012, 12:26 PM
Rocket Programmer
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United States, AZ, Mesa
Joined Jul 2007
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Originally Posted by acetech09 View Post
That generates sound based on a servo signal, usually tied to the throttle so it can generate engine sounds. It could probably broadcast a voice recording too, but it wouldn't be like a flying PA system with a ground-based microphone.
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Old Nov 11, 2012, 07:37 PM
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Originally Posted by richard hanson View Post
No surprise to me -
A a 4.8 v 750 ma pack -even fully charged is typically far smaller than all but the most tiny servos can use.
I got into a little discussion with a guy on using th 2000ma ENELOOPS as rx packs - he said -they sell em as rx packs and they work.
In testing them using Horizon ampmeter set on 2 amps - -each pack of four I tested (I have a bunch of latest ENELOOP) dropped instantly from 5.5 v to 3.8 aprox-that is a 1.7 volt drop!
As long as users persist in using cells with little ability to resist voltage depression- the problem with "rx failure" will just keep on going.
I don't expect the problem to go away-
Im not sure how you tested your setup, but there is obviously something faulty with something in that pack. http://www.candlepowerforums.com/vb/...ischarge-study Has an AA Eneloop discharged at 10 amps and it didnt go below 1.0v for the cell...

I personally tested a AAA 750mah Eneloop with a battery analyzer and at 1amp discharge it dropped to 1.25v for the cell after a few minutes, which is a higher C-rating discharge than your test.

Is it the perfect battery for a receiver pack ? No not compared to a higher discharge/lighter life or lipo.
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Old Nov 11, 2012, 07:59 PM
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Originally Posted by pach View Post
Im not sure how you tested your setup, but there is obviously something faulty with something in that pack. http://www.candlepowerforums.com/vb/...ischarge-study Has an AA Eneloop discharged at 10 amps and it didnt go below 1.0v for the cell...

I personally tested a AAA 750mah Eneloop with a battery analyzer and at 1amp discharge it dropped to 1.25v for the cell after a few minutes, which is a higher C-rating discharge than your test.

Is it the perfect battery for a receiver pack ? No not compared to a higher discharge/lighter life or lipo.
Easy to repeat my test - I used a stock (new) digital Variable Loadmeter by HANGER 9.

The wires on these and on HD receivers andservos are rated for constant 3 amps max.
The criteria was to have a pack which stayed well into the 4 volt range under load- this allowed a one volt drop- The ENELOOPS as I noted fell into the high 3 volt range -

The ENELOOP discharge chart is not for the same results . There was nothing faulty in the packs . I have at leat 6 of these sets - which I charge on the ENELOOP charger as wel as my ASTRO 12 charger
the cells are all in excellent shape.
ENELOOP shows the internal resistance to bequite high in these cells - so the results really did not surprise me
My DX8 * txs both use these cells and they work very well - weeks between charges.
My Canon camera, same - as well as all my tv remotes etc..
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Old Nov 11, 2012, 08:03 PM
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Did you test each cells individually to see if you had a bad one ?
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Old Nov 11, 2012, 08:05 PM
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absolutely - my meters read to three places - the cells are all good
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Old Nov 11, 2012, 08:40 PM
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Originally Posted by richard hanson View Post
absolutely - my meters read to three places - the cells are all good
I just did a retest differently to see if there was something I was missing which would screw up the test.
The tests were repeated on two packs -which were in spring clip holders from Futaba tx.- these read perfectly with no load but when 2 amp load was applied , the reading at the battery wiring connections read 4.4 volts as opposed to 3.8 at the test meter! No load was 5.4
Obviously both my good old spring clip packs have LOTS of resistance not in the spring clips but from the wire connector to the test meter connection!
So the ENELOOPS are not as bad as my other tests showed but still a volt or more drop at 2 amps load
Now imagine having high resistance cells and high resistance connections - under load - in the model - A no load test would never show a problem.


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Old Nov 12, 2012, 06:53 AM
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When load testing batterys, always use the four-terminal-sensing.

http://en.wikipedia.org/wiki/Four-terminal_sensing

If this is not done appropriately, the high resistance of the wires, connectors, contacts etc. may fool one into believing that it is the battery which has a high internal resistance.
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Old Nov 12, 2012, 07:26 AM
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Yes -
Iwas trying to do the tests in a manner where others could easily replicate the results
The surprise was that both spring holder s had almost identical high resistance in wiring.
I still was not satisfied that the ENELOOPS had low enough internal resistance for my use-as rx batts
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Old Nov 12, 2012, 07:55 AM
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United Kingdom, North York
Joined Feb 2003
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Quote:
Originally Posted by richard hanson View Post
Yes -

I still was not satisfied that the ENELOOPS had low enough internal resistance for my use-as rx batts
Your measuring with the Batts. in Tx Batt holders
These are not meant to be used at 2A, more likely around 200mA in Tx use

For a Proper Test make a soldered Rx pack up
using suitable wiring for the load you intend applying
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Old Nov 12, 2012, 08:18 AM
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I am glad I retried the test - I will be making a better cell testing setup for the ENELOOPS .
I knew that the crimped connections (std servo leads ) had high resistance but did not expect the total small wire and ends resistance to be as bad as it prooved to be .
Easy to see how some guys blamed rx for failure when power delivery was real issue
I have a box of extensions made by various mfgrs and in various sizes .
Some of these are just junk.
To add to the problem- There are now lightweight extensions available - which could easily be adapted as battery power leads .
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Old Nov 12, 2012, 08:40 AM
Proud to eat Kraut ;-)
Julez's Avatar
Germany
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Maybe that explains why I have no problems with eneloops in my large glider: I personally soldered the pack, and connected it to the RX with a Multiplex plug, which is rated for 30A. No switch in between.
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Old Nov 12, 2012, 09:43 AM
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You would have eliminated a very possible problem -
When I tested other soldered packs - I saw less voltage depression.
The combined losses are very sneaky! (betrugerish)
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Old Nov 12, 2012, 10:55 AM
Taranis Tyro...
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United Kingdom, England, Hitchin
Joined Jan 2004
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Quote:
Originally Posted by richard hanson View Post
I am glad I retried the test - I will be making a better cell testing setup for the ENELOOPS .
I knew that the crimped connections (std servo leads ) had high resistance but did not expect the total small wire and ends resistance to be as bad as it prooved to be .
Easy to see how some guys blamed rx for failure when power delivery was real issue
I have a box of extensions made by various mfgrs and in various sizes .
Some of these are just junk.
To add to the problem- There are now lightweight extensions available - which could easily be adapted as battery power leads .
Interesting - I did some more research found your original thread on Eneloop RX packs. I guess you have have changed your tune on the validity of your original testing setup after all...
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Old Nov 12, 2012, 11:24 AM
TRB
United States, TX, Richardson
Joined Oct 2005
91 Posts
Eneloops are very good cells with very good high-current characteristics. Not as good as dedicated high-current, high-capacity cells, but the overall performance considering the low-self-discharge makes Eneloops some of the best Nimh cells out there. I'm powering my Slow stick on 8 Eneloops.

Quote:
Obviously both my good old spring clip packs have LOTS of resistance not in the spring clips but from the wire connector to the test meter connection!
What kind of packs are you using? If the cells are not soldered together, it's not a pack. Period. AA-battery holders with the steel springs are absolutely worthless for any medium-current application. In fact the springs will get hot and melt through the plastic at quite moderate current draws.

I'm not easily deterred so in the past I have modified AA battery holders with strips of copper between the cells and the springs. It cuts down on the melting but still isn't as good as soldering or spot-welding.
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