A123 Mah usage (Full Version)

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Josey Wales -> A123 Mah usage (8/26/2007 11:04:23 PM)

Since switching over to the A123 on my 50cc Yak I have noticed a pretty big reduction in Mah-per-flight usage..I used to use 250 per 12 min flight--all 3D..now Im averaging 140 per 12 min flight...any ideas why ? Nothing has changed except the batteries---not that Im complaining or anything! [:)]



Bob Pastorello -> RE: A123 Mah usage (8/26/2007 11:45:43 PM)

You KNEW I'd chime in here.....[:D]
1. More stable, consistent voltage to servos; they work less hard
2. Because of 1., you're probably making less larger corrections, because of the ability of the servos to HOLD because the voltage isn't dropping under heavy loads

OR

3. It's all in your imagination, and you have flawed measurement equipment.

[:)]

(I was, and am, really surprised at how little mah all my Hitec 5955's really DO use in operation. Nothing like we've been led to believe all these years....)



onewasp -> RE: A123 Mah usage (8/27/2007 1:52:44 AM)

Nope. #3 is out. Possible but unlikely ---- TIC by Bob anyway.

Assuming the same 'work' load (and no regulator @ 6.6v nominal the on charge voltage of 7.2+/- will drop rather quickly so reg. is not needed).
You've got additional voltage applied so the current drain goes down. Since the current drain goes down the mah out drops.

Want a non RC world actual example-------automotive usage on the 6 volt to 12 volt. Exactly 1/2 as the voltage applied doubled.
Same principle applies.

Rx handles up to 9 volts easily----servos rated @ 6 volts------less life due to the higher applied voltage---------Now try and measure a few weeks in a servo's life span ----- trust me you won't be able to ID it. No matter how hard you try!



Josey Wales -> RE: A123 Mah usage (8/27/2007 1:58:46 AM)


quote:

ORIGINAL: aerobob

3. It's all in your imagination, and you have flawed measurement equipment.

[:)]



Well I am calculating my usage with the Cellpro by reading how much is put back into the pack---so far its been pretty much exact and consistent

Prior I was using the Accucycle Elite using the same method



Bob Pastorello -> RE: A123 Mah usage (8/27/2007 2:00:17 AM)

I was harassing you, Joe. I know the Cell Pro is accurate, and onewasp just offered a really good, undertable explanation of the phenomenon.



Josey Wales -> RE: A123 Mah usage (8/27/2007 2:12:18 AM)


quote:

ORIGINAL: aerobob

I was harassing you, Joe. I know the Cell Pro is accurate, and onewasp just offered a really good, undertable explanation of the phenomenon.


Oh yea--I know[:)]..sometimes when you write it you realize you eff'd up somewhere----Im not complaining at all!![8D]



k_caller -> RE: A123 Mah usage (8/31/2007 9:49:59 PM)

Hello,
I just read your post and had to inquire about hese batteries you're using.
I just bought 2 in-line packs of the A123 2300ma 6.6v batteries. I'm planning on using them in my Wigens with 7 or 8 HiTec 625 servos with a DPSI 2001. Are these batteries really enough power?
Also, what charging program should I use for these? LiOn or LiPo or? I have a Graupner Ultra Duo 30 Plus charger which is capable of charging just about anything on the market. The guys in the LHS were not sure but they suggested using the LiOn program set to 2300ma, 2 cells, and 6.6V. Supposedly I can charge these at a 4C rate but how?
Appreciate any ideas and suggestions.
Thanks



dick Hanson -> RE: A123 Mah usage (9/1/2007 1:31:26 AM)

any amperage you want - 4 amps is fine

best to use constant voltage charge -
exa,ple
start with 4 amps and set to 7.2volts
the cells are 3.6 each -which is a peaked reading
use a volt meter and read the cell voltage if possible -
if correct the charger or YOU stop charge at 7.2.
this is ideal but not critical -just don't go to 4.2 volts per cell except in freezing weather
when pack is settled - typical voltage will read about 3.4 per cell and under a very small load will drop and then work hard at 3.3 volts per celltill 2000mah is consumed -then it will end quite quickly - not a problem -just recharge.



JettPilot -> RE: A123 Mah usage (9/28/2007 6:16:09 AM)

quote:

ORIGINAL: Josey Wales

Well I am calculating my usage with the Cellpro by reading how much is put back into the pack---so far its been pretty much exact and consistent

Prior I was using the Accucycle Elite using the same method


You might be USING almost the same power as before, it might be a matter of battery efficiency. Some batteries take more charge to get to the same level and others take less, in other words, most of the energy is held in the battery as a charge rather than wasted. Maybe your old batteries wasted a bunch of the charge you were putting in... So you always put in more for the SAME usage.

So given the way you are measuring, you are NOT measuring usage, you are measuring charge and making some very bad assumptions based on that.

JettPilot



Josey Wales -> RE: A123 Mah usage (9/28/2007 12:19:01 PM)

So then how DO you measure it then ?--Ive been flying these most of the summer and those readings are very constant--even after just a single flight



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