[NSRCA-discussion] UBEC

Thu Mar 30 06:06:56 AKST 2006

Hello All,
I am going to get real busy, for the next couple of weeks here at work, so a few hours after this e-mail, I will have to leave the list for a bit.

Pat,
Let me make a couple of troubleshooting suggestions:
1) check the output voltage.
2) make the wires from battery to UBEC as short as possible, and keep them as far away from the antenna and any other wiring as possible.
3) keep the wire from UBEC to RX away from the antenna and other wires, but this is not as critical as the input side.
4) tightly twist the two wires from the battery to UBEC.

Most switching regulator designs pull pulsed current from the battery. Some pull a current that changes abruptly from nothing to something large, in a sorta' square wave shape. This is a horrible interference generator. Other circuit topologies pull current from the battery that has a large triangle-shaped ripple. This makes the wires from the battery into awful radiators. No manufacturer makes a "no input ripple current" type regulator for our purposes, though it is do-able. It would be somewhat larger and heavier than the UBEC. 

Chad,
I hear your problem with the inlet cheeks on the Twister. Who says that cooling air must go front-to-back all the time? Think about taking air from the existing chheks, into a plenum surrounding the back of the 30-10. Use a duct like mine or Earl's, and dump into a plenum in front of the motor. You may need a shaft extension to get the motor back 3/4" or so, to get a decent volume. Then place rear-facing outlet scoops, just behind the spinner, to suck the air out of the front plenumm. I keep imagining a turbo-prop exhaust pipe. You could even use an oversize spinner and a large spinner to fuse gap (aesthetically yuck!) to create a vaccuum at the motor front.

I'll still be on the list 'till lunchtime.

Dean

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Pat Hewitt
Sent: Wednesday, March 29, 2006 10:11 PM
To: NSRCA Mailing List; 'NSRCA Mailing List'
Subject: [NSRCA-discussion] UBEC

I ask this question a couple days ago but not one reply so I am thinking it
did not go out.

I am new to this E-Power thing and my first day to the field had a bad RF
problem. So for my set up Plane is an ABBRA, Hacker C50 Comp. Hacker 90
controller, TP-5300's I am using a UBEC not a second battery. JR 770 slimline
PCM with this I could not get 25' with out major RF. First and only thing I
did was remove the UBEC place a second battery in and had NO RF walked over
200'. I know some will say just use the second battery but I need to why
because a friend that got me into the E thing has never had a problem in fact
he has the same setup in a sport plane and has had NO problems.

Thanks

Pat Hewitt

------ Original Message ------
Received: 07:32 PM CST, 03/29/2006
From: "Park, Ihncheol" <PnAHobbies at sbcglobal.net>
To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Interesting Battery stuff

Isn't "a123" the batteries that Sony is currently using in their MP3
players?

Ihncheol Park

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of brett terry
Sent: Wednesday, March 29, 2006 6:38 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Interesting Battery stuff

I had a long response ready, until a server crash dumped my message.

There is a long thread about these cells in the electric helicopter forum on
RCGroups.  They exhibit a greater voltage depression under load than LiPo
cells, but they seem to have great success pulling 50+ amps continually with
bursts of 100A.  The cells they are using come from the Milwaukee 28V drill,
weigh 100 grams each, and are 3000 mAh capacity.  Best of all, a 7-cell pack
(28V) costs around $100. 

Both manufacturers (a123 systems and eMoli) refuse to sell directly to RC
guys, but stripping the cells from the Milwaukee battery pack seems easy
enough.

Pros:
cheap!
reliable
readily available
durable construction

Cons:
somewhat heavy for their capacity compared to LiPo
increased voltage depression under load requires running an extra cell (7S
vs. 6S, for example)

There is a thread on RCGroups under the ELectric Helicopter forum about
these cells.  Here is the link.  Be warned the post is about 78 pages long
now.   Page 22 (and several others) has charts showing voltage with watts
and voltage with amps over time. 

http://www.rcgroups.com/forums/showthread.php?t=456011

On 3/28/06, Stuart Chale <schale at optonline.net> wrote: 

http://www.a123systems.com/html/tech/power.html

Above is their technology page.  35C discharge.  5 minute charge.  

Anyone with good battery knowledge take a look at this?  Is this the no
worry cells that will convince everyone to go electric :-) 

If only they live up to their advertising :-)

Stuart

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Cameron Smith
Sent: Tuesday, March 28, 2006 8:56 AM
To: Discussion
Subject: [NSRCA-discussion] Interesting Battery stuff

http://www.a123systems.com/html/technology.html#
<http://www.a123systems.com/html/technology.html> 

http://www.technologyreview.com/BizTech-R
<http://www.technologyreview.com/BizTech-R&D/wtr_16624,295,p1.html>
&D/wtr_16624,295,p1.html

http://store.yahoo.com/poe512000/ma18vlxtlico.html
<http://store.yahoo.com/poe512000/ma18vlxtlico.html> 

45-minute Optimum Charger and battery communicates throughout the charging
process using the built-in chip in the battery and built-in CPU chip in the
charger. The Charger also uses "Active 3 Control" for current control,
thermal control & voltage control

http://blogs.toolbarn.com/mattg/2006/01/smells-like-dewalt-spirit.html

It seems that their DC9360 battery will use exclusive nano-phosphate
lithium-ion cells. They deliver two to three times the run-time compared
with their current 18 volt batteries. DEWALT is anticipating 2000 recharge
cycles on the battery, which is a significant increase. The battery is
slated to be 2.4 pounds which is roughly the same weight as their current 18
volt batteries. Otherwise, it will be a slide on style, instead of the
familiar pod currently in use.

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