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A-123 2 cell pack and Servo compability

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Old 06-16-2007, 06:46 AM
  #1  
d_wheel
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Default A-123 2 cell pack and Servo compability

I have read that some people are using 2, A-123 cells in series to power their receiver/servos. The voltage of a fully charged pack would be 7.2 volts. I realize that this would quickly fall to the working voltage but am curious if the higher voltage will damage the servos. What servos have been used with these cells without damage?

Later;

D.W.

Updated 06/17/07

Here is a list of servos that have been used with 2S A123 battery packs. They are divided into those that have actually been flown, and those that have been bench tested:

Bench tested:
Futaba 3001, 3010, 9204, 9303, 9202.
Spektrum DS821.

Flown:
Hitec 5945, 5955TG, 5625.

If you have any to add to the list, please let me know.

Later;

D.W.
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Old 06-16-2007, 08:36 AM
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Default RE: A-123 2 cell pack and Servo compability

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Old 06-16-2007, 09:49 AM
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Default RE: A-123 2 cell pack and Servo compability

I think it would depend a great deal on the load you subject them to. The servos draw the current needed for the load. The higher voltage simply allows the servo to draw a larger current.
I tested a Hitec 5955 at full load on 7.4 volts. It lasted about three minutes before it blew the amplifer. You are never going to subject such a servo for that load for as long as three minutes unless you have it in a crane that is lifting a weight or similar.
The JR 8611A burned out its motor in about 10 seconds when subjected to full load on 6V. In fact I burned out three of those trying to test them. I would be more careful with those.
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Old 06-16-2007, 10:13 AM
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Default RE: A-123 2 cell pack and Servo compability

dirtybird
Hitec have really stepped their game up. I just ordered me 5-5955TG. They have arrived I can't imagine these servos being as tight as they are now years later. I have about 20-8411 and 1-8611 on various other birds but to me JR has lost their edge and don't seem to be at it like they use to be in the servo dept. What do you do to subject a servo load to have it fail?

tks
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Old 06-16-2007, 11:07 AM
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Default RE: A-123 2 cell pack and Servo compability

IF it was a sustained 7.2v with most digitals it would damage the servo after a while, how long depends as stated on the total load. From information I have found talking to a few who are using them the working voltage quickly drops to about 6.6v, so as long as the servos are rated to work at 6v they should be ok. In comparison a 5 cell nimh packs peaks about 7.1v and quickly drops to around 6.5 or so. When its time to replace the packs in my smaller planes this is probably the route I will go. Use li-ion in all my big stuff, mostly to save weight.
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Old 06-16-2007, 03:08 PM
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Default RE: A-123 2 cell pack and Servo compability


ORIGINAL: krayzc-RCU

dirtybird
Hitec have really stepped their game up. I just ordered me 5-5955TG. They have arrived I can't imagine these servos being as tight as they are now years later. I have about 20-8411 and 1-8611 on various other birds but to me JR has lost their edge and don't seem to be at it like they use to be in the servo dept. What do you do to subject a servo load to have it fail?

tks
www.servotestsite.com explains my testing. The site is still there after I quit paying for it. I just can't change anything.
Overall I rate the 5955 as the best servo I tested even if I could only get about 60% of the torque out of it that they clain.
The 8611A tested the highest torque but the curve is such that you will never get anywhere near that in normal operation. It just takes too much difference between the servo position and its commanded position to get it. That will keep you from burning it out.
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Old 06-17-2007, 03:01 PM
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Default RE: A-123 2 cell pack and Servo compability

I've started compiling a list of compatible servos. I will update post #1 when new data is added.
If you have any to add to the list, please let me know.

Later;

D.W.
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Old 06-20-2007, 04:15 PM
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Default RE: A-123 2 cell pack and Servo compability

The A123s that I fly in my planes are only 6.9v off charger. 6.6v with 1A load. They are charged with a Cellpro.
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Old 06-20-2007, 04:28 PM
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Default RE: A-123 2 cell pack and Servo compability

FWIW--any servos which work well with a non regulated 5 cell Ni Cad or NiMh pack --will work with 123 cells .
actually the "100% charge from the CellPro 4 charger is LOWER in voltage than a 100% charged, quality , low impedance NiMh - 5 cell pack
so-------------------- the NET advantage of the 123 is that it starts at about 6.6 v and stays there --down to about 6.3 volts till pack is about 3/4 or more, depleted .
essentially you get a regulated "6.5V" output with NO regulator -plus far more current on demand than any regulated setup. thru entire effective charge.

You wil have to monitor YOUR setup and see how much current you use per flight - If you don't already know this ----you really should find out.
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Old 06-21-2007, 03:17 PM
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Default RE: A-123 2 cell pack and Servo compability

Dick you mentioned before where you bought your 123 Cells but I forgot. Did you raid a DeWalt pack?

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Old 06-21-2007, 03:32 PM
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Default RE: A-123 2 cell pack and Servo compability

I stole a pack and ran out the store --
the pack is the DeWalt 36 volt ONLY. not any other De Walt packs
EBay good prices
Horizon also has then in various combos 20$ apiece for singles I also have those --and-- I also bought a ready to go pack from vendor.
To be candid --best price is to buy 10 (one pack ) from EBay. as long as cells are new - who cares . Maybe you will luck out and find a carton which "fell off a truck"-------------------
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Old 06-21-2007, 06:25 PM
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Default RE: A-123 2 cell pack and Servo compability


ORIGINAL: dick Hanson

I stole a pack and ran out the store --
the pack is the DeWalt 36 volt ONLY. not any other De Walt packs
EBay good prices
Horizon also has then in various combos 20$ apiece for singles I also have those --and-- I also bought a ready to go pack from vendor.
To be candid --best price is to buy 10 (one pack ) from EBay. as long as cells are new - who cares . Maybe you will luck out and find a carton which "fell off a truck"-------------------

Thanks - and if you don't mind some more questions...I hate soldering cells by hand. Is that how you assembled them? Also, what charger do you use? I have a Triton that meets my needs well and don't want to invest in another.

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Old 06-21-2007, 06:55 PM
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Default RE: A-123 2 cell pack and Servo compability

Tabs are on all of em - no sweat - blow a few bucks to get a CellPro4 cell A123 charger -also good for Lipos
it is 80 bucks but as things stand -I think it is the best
really a much simpler one will work - a DAPTER used with your charge (39 buks) is great but the learning curve is higher .
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Old 07-05-2007, 04:24 PM
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Default RE: A-123 2 cell pack and Servo compability

dick hanson: Can you get the 123 cells out of some battery pack made for a electric drill? I and my Grandson are geting into electricc airplanes. Best Regards capt,n
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Old 07-05-2007, 05:16 PM
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Default RE: A-123 2 cell pack and Servo compability

Just one pack -- the DeWalt 36 volt pack
The pack will cost you about --$100-$130 on EBay - or $180 at a retailer .
so each of the ten cells will be 10 - 18 bucks each.
Horizon sells em at about 20 bucks each
IF you buy them from EBay and you have too many - post the remainder for sale -I betcha they go faster than a rat up a drain pipe -
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Old 07-06-2007, 09:23 AM
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Default RE: A-123 2 cell pack and Servo compability

I bought a pack off of ebay and used six cells for my starter. Whats a good airplane to use the other four cells in?
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Old 07-06-2007, 10:05 AM
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Default RE: A-123 2 cell pack and Servo compability

well -- here are two I am doing -- the Diamante and the AJ 300 I love the setup a 32 Eflite motor a overkill 75 amp Align ESC and a BEC by Parkbec
I wouldn't trade the 4 cell 123 setup for the LiPos --on a bet .
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