SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Apr 21, 2006, 09:08 AM
Registered User
taekwondo's Avatar
USA, FL, Orlando
Joined May 2003
7,977 Posts
Discussion
BEC 4s1p made from 2 cell packs

Everyone:

I have a question regarding using BEC on a 4s1p made from 2 cell packs. I purchased 4 two cell packs with the intention of making 2 4s1p packs. I later found out I needed to use a BEC so as to not burn out the receiver because of the higher voltage. Question is, which BEC would you guys recommend, where can I get it and do they all work basically the same? I'm planning on using this in my larger planes, I have a electric telemaster with 6' wingspan and I am using an axi 2826-12 with an apc sf 13" x 6.5 pitch prop. I don't have access to moto calc. Thanks for your help in advance.

Henry
taekwondo is offline Find More Posts by taekwondo
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 21, 2006, 09:10 AM
Registered User
taekwondo's Avatar
USA, FL, Orlando
Joined May 2003
7,977 Posts
Sorry, I forgot to mention. Obviously, I will be wiring them in series.
taekwondo is offline Find More Posts by taekwondo
Reply With Quote
Old Apr 21, 2006, 10:35 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,812 Posts
Series / parallel

http://www.commonsenserc.com/page.ph...l_diagram.html

UBEC

http://www.rcmodelworks.com/xcart/pr...t=0&bestseller

BECs

http://www.rcgroups.com/pages/splist/link.php?s=527


Charles
everydayflyer is online now Find More Posts by everydayflyer
Reply With Quote
Old Apr 21, 2006, 10:41 AM
Registered User
dave morris's Avatar
orlando fl
Joined Oct 2000
5,713 Posts
Ubec and Parkbec are a couple. Ubec is made by Koolflight, and the parkbec is dimension engineering.

One thing to watch out for is the chance for interference from the switching BEC, just be sure a do a very good range check, if if fails you can try rearanging the wireing and placement of the BEC.

BTW your Rx will not burn out, but the BEC built into the ESC can.

Besure to disable the built in BEC before using an external power source.
dave morris is offline Find More Posts by dave morris
Reply With Quote
Old Apr 21, 2006, 10:42 AM
Registered User
dave morris's Avatar
orlando fl
Joined Oct 2000
5,713 Posts
opps Charles beat me to it.
dave morris is offline Find More Posts by dave morris
Reply With Quote
Old Apr 21, 2006, 11:26 AM
Registered User
taekwondo's Avatar
USA, FL, Orlando
Joined May 2003
7,977 Posts
Charles:

Thanks for the info. Based on what I read here briefly,

If you are using a speed controller with a built-in BEC, it will very likely have only a limited ability to supply power to your receive and servos without overheating, if you have a relatively high-voltage battery pack or have high servo loads. Consult the speed controller specifications to determine what the stated recommendations or limitations are. In general, if you are using a 4S Lithium pack, or more than a 12-cell Nickel based pack, you should consider using the UBER-BEC

The ubec would be the way to go if I decide on 4s1p. But really, in thinking about it, I should find out if it is at all possible to use the batts in a 2s2p configuration. They are Polyquest 12c 3100 mah, capable of about 36 amps draw each. If I'm not mistaken, this means 72 amps together in the 2s2p configuration. Do you have a link to pcalc or motor calc or some free software so I can check if this would work or do you know yourself?

The park bec said it wouldn't work on 2s so that's out. I flew this plane twice on the 3s2p configuration at 1/2 power with a friends batteries. If I used a 2s2p configuration, would I use a bigger prop? Thanks for your help in this matter.

Kindest regards,
Henry
taekwondo is offline Find More Posts by taekwondo
Reply With Quote
Old Apr 21, 2006, 11:29 AM
Registered User
taekwondo's Avatar
USA, FL, Orlando
Joined May 2003
7,977 Posts
Quote:
Originally Posted by dave morris
Ubec and Parkbec are a couple. Ubec is made by Koolflight, and the parkbec is dimension engineering.

One thing to watch out for is the chance for interference from the switching BEC, just be sure a do a very good range check, if if fails you can try rearanging the wireing and placement of the BEC.

BTW your Rx will not burn out, but the BEC built into the ESC can.

Besure to disable the built in BEC before using an external power source.
Dave:

Thanks for the information. You said 'Besure to disable the built in BEC before using an external power source.' how do you disable it, with a software programming code? Sounds like the bec/park bec methods are going to be complicated for me. I just ordered 2 3s1p batts which I can use in the 3s2p configuration and utilize these batts else where or if I can get it to work, then I will have a 4s1p configuration possible as well. Thanks for your help.
Henry
taekwondo is offline Find More Posts by taekwondo
Reply With Quote
Old Apr 21, 2006, 11:34 AM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
Quote:
Originally Posted by taekwondo
Dave:

Thanks for the information. You said 'Besure to disable the built in BEC before using an external power source.' how do you disable it, with a software programming code? Sounds like the bec/park bec methods are going to be complicated for me. I just ordered 2 3s1p batts which I can use in the 3s2p configuration and utilize these batts else where or if I can get it to work, then I will have a 4s1p configuration possible as well. Thanks for your help.
Henry
Pull the red wire out of the connector going to the RX and tape/shrink wrap it.
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Apr 21, 2006, 11:46 AM
Dismembered Member...
arx_n_sparx's Avatar
Niagara Falls/Toronto area
Joined Dec 2003
4,536 Posts
http://www.rcgroups.com/forums/showthread.php?t=326226

Start reading at post #90. It's tough to beat a $1.00 UBEC

Brad
arx_n_sparx is offline Find More Posts by arx_n_sparx
Reply With Quote
Old Apr 21, 2006, 12:41 PM
Dimension Engineering
Akron, Ohio
Joined Jan 2002
1,705 Posts
Quote:
Originally Posted by taekwondo
Dave:

Thanks for the information. You said 'Besure to disable the built in BEC before using an external power source.' how do you disable it, with a software programming code? Sounds like the bec/park bec methods are going to be complicated for me. I just ordered 2 3s1p batts which I can use in the 3s2p configuration and utilize these batts else where or if I can get it to work, then I will have a 4s1p configuration possible as well. Thanks for your help.
Henry

A parkBEC disables the ESC BEC automatically if you follow the installation instructions. It installs inline between the ESC and RX.

On 2s you almost certainly don't need a switching BEC. The heat generated by the linear BEC in your speed control is a function of the difference between the input and output voltage. On 2s, thats only going to be about 2V. On 3s, its about 5V difference, so 2.5X the heat. With 4s, its more like 8 volts, so 4X the heat.
Comatose is offline Find More Posts by Comatose
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Li Ion packs I made from surplus cell phone batteries daveoner Batteries and Chargers 19 May 13, 2004 09:13 PM
FS: 1300mA Lithium-ion 2 cell packs Twmaster Aircraft - Electric - Airplanes (FS/W) 4 Feb 13, 2003 12:28 AM
Kokam 2-cell packs in parallel SoaringDragon Batteries and Chargers 1 Dec 31, 2002 08:19 PM
FS: Li-Ion 3-cell 1250/1350mah & LiPoly 145mah 2-cell packs Danny Troy Aircraft - Electric - Airplanes (FS/W) 2 Oct 17, 2002 02:34 PM
Lithium Ion Charger For 2 Cell Packs tnrwayne Aircraft - Electric - Airplanes (FS/W) 2 May 30, 2002 12:07 PM