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Old Mar 02, 2003, 03:53 PM
Registered User
West Chester, OH USA
Joined Jan 2000
1,052 Posts
HS-81 vs Hs-85 current draw?

Hi All,
I am finishing up a Waco Bipe that I have had laying around for awhile. I will be using a Kontronic Easy 4000 ESC with 10 cells powering four servos. I have used this ESC in other 10 cell/4 servo applications with good results using HS-81 or HS-55 servos. I had intended to use HS-81 servos all around on this plane, but discovered that I was one servo short. However, I do have a HS-85 servo from a deceased plane that I could use. My concern is that since this is a higher torque servo that is basically the same size as an HS-81, I suspect that it will draw more current. The specs on Hitec's website don't include any current draws, so I'm wondering if anyone knows if indeed the HS-85s draw more current (in which case I'll buy another HS-81), or not.

TIA,
Don
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Old Mar 03, 2003, 03:40 AM
(aka Cliff Lawson)
Wright Flyer's Avatar
United Kingdom, Essex
Joined Oct 2001
1,897 Posts
Just a thought but rather than buying another servo you could get a uBEC for around the same amount - it's a battery eliminator that operates separate from your ESC and has a MUCH higher current sourcing ability than the low spec BEC circuit in most ESC's. Obviously the more cells you have the harder a BEC has to work and at 10 cells a uBEC could be the safe choice (it's often used in e-helis where there are LOADS of cells and also loads of 4.8V electronics to be powered).

Cliff
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Old Mar 03, 2003, 05:08 AM
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Haldor's Avatar
Stavanger, Norway
Joined Feb 2000
7,999 Posts
The HS85 has higher torque but this comes from longer transition time, not more input power. I'd say they consume about the same.
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Old Mar 03, 2003, 02:19 PM
Registered User
West Chester, OH USA
Joined Jan 2000
1,052 Posts
Cliff,
The UBEC is intriquing. I do intend to buy a couple of them to replace RX packs in a 14 cell and 16 cell plane. I hate having to remember to charge the RX packs the night before flying.

Haldor,
I checked the Hitec website again, and you are right - the HS-85 is slower. Given that information, I think I'll be alright to leave the HS-85 installed. BTW - I was wrong about the model of ESC - it's a Sun 4000, not the older Easy 4000. I believe the BEC capacity was upgraded in the Sun ESCs. Thanks for your help.

Regards,
Don
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Old Sep 16, 2003, 10:58 AM
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Kevin Murray's Avatar
USA, NC, Greenville
Joined Dec 1999
9,271 Posts
servocity.com lists the idle and stalled draw in all of the HiTec servos. In the spec part on each servo's page.
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