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Old Apr 22, 2004, 11:32 AM
H2OFLY
Portland Oregon USA
Joined Feb 2000
2,509 Posts
How much voltage is too much for this Aveox motor?

Couldn't find this on the Aveox site: I know that too much voltage into a motor can overspeed it - throw windings, overheat, etc.

I have an Aveox 1412/3y with the Robbe 3.7:1 planetary gearbox, and would like to use 8s Lipo's. My concern is that I have used it for years with 20 and 21 cells (NiCd and NiMh) but never with Lipo's. I believe that a 7s lipo battery would emulate 21-cell 'old chemistry' performance, but prefer to use 8s lipo for reduced current with the same gearbox and prop.

Do you have specs on Max Voltage into the motor? And, how are the Lipo's rated, per cell? I am used to the 1.2 v or 1.25 v per cell for NiCd and NiMh, but am hearing some say "use 3v for Lips" yet I note that a fully charged cell is 4.2 v.

Thanks!

Terry
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Old Apr 23, 2004, 04:53 AM
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plinse's Avatar
Baden Baden, Germany
Joined Feb 2001
1,059 Posts
Quote:
Originally Posted by Terry

...

I believe that a 7s lipo battery would emulate 21-cell 'old chemistry' performance, but prefer to use 8s lipo for reduced current with the same gearbox and prop.

...
I think you have a mistake in your thouht: More voltage with the same gearbox and prop gives higher current.

By the way just look for the max rpm Aveox gives for the motor and the RPM/V and calculate the max voltage. This is close to the situation you have in a dive with motor on.

Eike
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Old Apr 23, 2004, 05:30 AM
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davidfee's Avatar
San Diego, CA, USA
Joined Mar 2001
3,068 Posts
Terry,
Did you get the new carbon-wrapped rotor for your 1412? Aveox lists a max RPM of 50,000 for the current 36/30/3Y. With a kv of 1011, that works out to about 50V unloaded (as in a dive on a geardrive like Eike mentioned). I think you're probably safe from a voltage standpoint, but I can't offer assistance with the lipo stuff.

-David
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Old Apr 23, 2004, 07:07 AM
Product Manager at Hobbico
GWRIGHT's Avatar
United States
Joined May 2000
5,156 Posts
I've ran 3S,4S,5S,6S,7S,8S,9S, 10S, 11S systems and find these pretty well suit the comparison., Figure 3.5 roundcells per lipo in series.

6S= 20~21 cells
7S=24 cells
8S= 27~28 cells
9S=30~31 cells
10S=34~35 cells

also,..the newest thunder power cells hold higher voltage under load, so you could approximate more roundcells for each config. For example, the new cells, a 10S4P pack is at 37 volts at an 81 amp load, so each lipo is equiv to 3.7 roundcells, or 10S is like a 37 cell pack. Since the unloaded voltage is 4.2 per cell, just make sure the ESC can handle it. For example, controllers I've used that are labeled for up to 30 cells, are assuming 45 volts unloaded (1.5V per roundcell) with a bit of cushion built in,.. and they actually handle 11S since that's only 46.2V unloaded and the actual practical limit is around 50~52 volts, but the manuf. are a bit conservative in their specs.
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Old Apr 23, 2004, 07:36 PM
H2OFLY
Portland Oregon USA
Joined Feb 2000
2,509 Posts
plinse - I had my brain turned off when I wrote "same prop" as I have been
thinking I would move from a 15x12 to a 15x8, to keep the current
under 30 amps. Thanks for spotting that goof.

davidfee - someone else mentioned the new rotor; I will contact Aveox
and see if, with my older motor, they would exchange it for a fee.

gwright - I appreciate your experience, Gary, and will post the "3.5 NiCd/NiMh
= one Lipo" on my wall over the bench
I will be using Tanic packs, because I'm too conservative to not
be able to check each individual cell as I get used to lipo's.

Mucho gracias, guys,

Terry
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