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Ask your electric FAQs HERE! - 5/17/2004 2:31:58 PM   
Matt Kirsch



Posts: 7037
Joined: 7/5/2002
From: Rochester, NY, USA
Status: online 		I think it's high time that the electric flight area of RCU had an Electric FAQ. It's always discouraging to have to send people over to the competition when they just need to know the basics. While I suppose we could simply plagiarize their FAQ, that's just not a nice thing to do, so let's create one from scratch.

What I need from you is your help. Anybody with basic questions, post them. Experts, please take a few minutes and post an answer or two.

Please refrain from asking about specific applications or specific products, or answering a question using a specific product if possible (e.g. Astro Whattmeter is okay because it's pretty much the only product of its kind on the market).

For now, we'll run it as a "Living FAQ," but I do intend to compile the answers into a single document, perhaps something we can post somewhere on the website.

< Message edited by Matt Kirsch -- 5/31/2004 3:10:27 PM >
       Post #: 1

RE: Ask your electric questions HERE! - 5/19/2004 3:27:53 AM   
hbruhn


 

Posts: 8
Joined: 5/18/2004
From: Beeton, , CANADA
Status: offline 		There is an other wattmeter on the market, better but also more expensive.
It is made by Graupner and looks and works like the one electrician use,
Clamps around a wire and that is it, no connecting to wires .

(in reply to Matt Kirsch)
       Post #: 2

RE: Ask your electric questions HERE! - 5/20/2004 7:02:52 AM   
Time Pilot



Posts: 1468
Joined: 10/25/2003
From: Vancouver, BC, CANADA
Status: offline 		I've asked this question today, but how to properly do a water break-in on a brushed motor.

I've read about it in a magazine, but it wasn't clear enough. How much of the motor needs to go in the water? How long does it need to dry out (should one use WD-40 to disperse the water)? Where exactly does the oil go after the motor is dry? How much oil? What kind of oil?

Pictures would be very helpful. For someone who doesn't know what names of the parts are, a description of what to do is not always that helpful.

(in reply to Matt Kirsch)
       Post #: 3

RE: Ask your electric questions HERE! - 5/21/2004 12:33:05 PM   
Matt Kirsch



Posts: 7037
Joined: 7/5/2002
From: Rochester, NY, USA
Status: online 		Well, this idea isn't going nearly as well as I thought it would...

Come on, guys! It takes but a second to post a simple electric question.

Thanks for your submissions so far, both of you.

< Message edited by Matt Kirsch -- 5/21/2004 7:33:35 AM >

(in reply to Time Pilot)
       Post #: 4

RE: Ask your electric questions HERE! - 5/21/2004 8:15:35 PM   
Greg Covey



Posts: 4375
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		Why should I fly electric? It seems more complicated and costly than glow-powered setups.

_____________________________

Visit my Web Hangar at www.gregcovey.com/rc.htm

(in reply to Matt Kirsch)
       Post #: 5

RE: Ask your electric questions HERE! - 5/22/2004 12:22:56 AM   
Jim Finn



Posts: 660
Joined: 10/15/2002
From: Lubbock, TX, USA
Status: offline 		Some of the advantages of flying electrics are: You can build as small or as large as you like............Quietness allows you to fly most anywhere...................No mess to clean up..................Planes stay looking new because of no fuel mess.................Quieter.............More challanging to fly ...............Quieter..............Smoother running...................Quieter..................no fuel smell on everything including your car.....no fuel purchase required..............Quieter.......Multi engines are a dream (no one motor qutiing)..........You can test your powerplant in your living room....and did i mention that it is quiteter?

_____________________________

" But that is just my opinion, I could be wrong" (Dennis Miller)

(in reply to Athlon)
       Post #: 6

RE: Ask your electric questions HERE! - 5/22/2004 12:27:29 AM   
Time Pilot



Posts: 1468
Joined: 10/25/2003
From: Vancouver, BC, CANADA
Status: offline 		How about these:

How and why (or why not) one would put a fuse on the electrical system?

How big of an ESC should you get for different motors?

How should you manage batteries to get maximum life out of them?

What is a rough guide to gearing, propping, and powering different kinds of planes (sometimes you want to convert a direct drive plane to a geared system, or upgrade from the manufacturers recommendations....)?

(in reply to Matt Kirsch)
       Post #: 7

RE: Ask your electric questions HERE! - 5/22/2004 12:34:52 AM   
Jim Finn



Posts: 660
Joined: 10/15/2002
From: Lubbock, TX, USA
Status: offline 		A rough guide to sizing planes to motors to props to cells is a computer program called "Electricalc" $40. Fuses are a source of failure and add weight. Many manufactures recommend them and few flyers use them.

_____________________________

" But that is just my opinion, I could be wrong" (Dennis Miller)

(in reply to Time Pilot)
       Post #: 8

RE: Ask your electric questions HERE! - 5/23/2004 9:58:42 PM   
Walt1



Posts: 67
Joined: 9/4/2003
From: tampa, FL,
Status: offline 		OK I'll bite!

I really could use some help understanding where my lippos should be as far as Max and Min charge.. I understand running them too low will do damage.

I have two battery packs One a 3 cell hacker 11.1V 3x700 mAh
the other a ThunderPower 860 mAh 7.4v 2 cell

I have a Radio Shack Multi meter.

Thanks guys!

Walt,

(in reply to Jim Finn)
       Post #: 9

RE: Ask your electric questions HERE! - 5/25/2004 2:17:29 AM   
Walt1



Posts: 67
Joined: 9/4/2003
From: tampa, FL,
Status: offline 		Well that worked out well!

(in reply to Walt1)
       Post #: 10

RE: Ask your electric questions HERE! - 5/25/2004 2:30:25 AM   
Jim Finn



Posts: 660
Joined: 10/15/2002
From: Lubbock, TX, USA
Status: offline 		I do not know enough about Lipos to comment. I use nicads. I do know that a wattmeter is what is needed to know what is going on with any battery pack. A multi meter does not tell you much about a batteries state of charge.

_____________________________

" But that is just my opinion, I could be wrong" (Dennis Miller)

(in reply to Walt1)
       Post #: 11

RE: Ask your electric questions HERE! - 5/25/2004 3:57:30 AM   
RickAvery


 

Posts: 617
Joined: 3/17/2004
From: Moorpark, CA, USA
Status: offline 		It was recommended that when I build up a wing that I not use a single conversion Rx. What is the difference between single and multi conversion Rx's, and what would be the advantage of one over the other? Would having a multi conversion Rx require a different Tx?
Rick

(in reply to Matt Kirsch)
       Post #: 12

RE: Ask your electric questions HERE! - 5/26/2004 7:11:20 AM   
Time Pilot



Posts: 1468
Joined: 10/25/2003
From: Vancouver, BC, CANADA
Status: offline 		It depends on the Rx. I use a Berg Stamp 4 which is a full range, single conversion, Rx that can be used in glow models.

The advice to stay away from the cheaper single conversion Rx's was likely because they are more prone to interference from other radios. How much I don't know because I've not used one but didn't get one because of what I read here at RCU. I choose to spend the extra $20 than take the chance of crashing because of a glitch.

As long as the Rx is on the same frequency as your Tx, and the Rx is compatible with your Tx, it doesn't matter whether your Rx is single or double conversion.

(in reply to RickAvery)
       Post #: 13

RE: Ask your electric questions HERE! - 5/26/2004 12:37:22 PM   
Matt Kirsch



Posts: 7037
Joined: 7/5/2002
From: Rochester, NY, USA
Status: online
quote:

ORIGINAL: Walt1
I really could use some help understanding where my lippos should be as far as Max and Min charge.. I understand running them too low will do damage.


Such information should be provided with the battery packs themselves, as overcharging seems to be the main cause of LiPoly fires.

For our purposes, LiPolys have a MAXIMUM voltage of 4.2 Volts per cell. You do not want the charge voltage to exceed that.

It is generally recommended that you also do not go below a MINIMUM voltage of 3.0 Volts per cell. Something on the order of 95% of the pack's capacity is in between 4.2V and 3.0V, so running it any lower doesn't really gain you much.

What does this mean for packs? To get the maximum and minimum voltages for a pack, you multiply the maximum and minimum cell voltages by the number of SERIES cells in the pack. An 11.1V pack has three cells connected in series. 3 times 4.2 Volts gives you a maximum voltage of 12.6 Volts. 3 times 3 Volts gives you a minimum of 9 Volts.

(in reply to Walt1)
       Post #: 14

RE: Ask your electric questions HERE! - 5/26/2004 3:04:39 PM   
Walt1



Posts: 67
Joined: 9/4/2003
From: tampa, FL,
Status: offline 		Thanks Matt!

walt,

(in reply to Matt Kirsch)
       Post #: 15

A question on LiPo cell packs. - 5/27/2004 4:38:45 AM   
Debonair



Posts: 6
Joined: 2/11/2002
From: Goshen, IN, USA
Status: offline 		Here is one for you.
I am building an electric powered Hangar 9 Aresti. I am using an AXI 4120/18, Jetti controller and 3 X 5S 1500Mah Kokam LiPo cells.
I built up the 5S packs myself from individual cells and was going to put shrink tube around them to hold the packs together like
the packs you get from vendors. My question is, should I place some kind of spacer between each cell in the packs to allow air to
circulate between them to cool them? If so, any suggestions what material to use and what thickness?
Thanks for your help.

(in reply to Walt1)
       Post #: 16

RE: Ask your electric questions HERE! - 5/27/2004 7:00:11 PM   
Matt Kirsch



Posts: 7037
Joined: 7/5/2002
From: Rochester, NY, USA
Status: online 		Guys,

Keep 'em coming, but please try to keep the questions basic. Think back to when you were starting out with electrics and how clueless you were. I'm looking to compile questions and answers for things like basic battery care, terminology (e.g. What do the motor numbers mean?), differences between types of motors, etc.. Stuff like that. Specific application questions should go in their own threads in their own appropriate forums!

We'll get it, slowly but surely.

(in reply to Debonair)