graniteguy

New to site, long time fuel flyer newb to electric. Couple of questions. I have the mini Funtana by e-flite with 480 motor, 40a speed control with bec. Question, there is a second lead off the thunder power battery that I dont know what it is too. There is a + and - the second one has a small plug. Second Q. do I need to put an on/off switch on an electric system? if so how do I wire it?

Thanks in advance.

Sir Raleigh

Welcome aboard and welcome to the wonderful world of electric flight...

If the type of battery you are asking about is a Lipo, then there are probably 2 leads and plugs coming out of it.
The red and black wires with the large plug supplies the main battery power to the ESC and can also be used to charge the battery.
The smaller wires and plug are used to charge and balance the battery.
If a battery is made up of more than one cell each cell needs to be at the same potential as the others. It's like having 2 or 3 glasses of water side by side and having the water level the same in all the glasses.
Balancing is how this is done.
There are 2 ways to balance a battery.

1) Balance the battery after it's been charged. This is like putting a tube between the glasses of water and have the water from the higher level drain into the glass with the lower level. The problem with this is that after all the cells are balanced the battery is no longer fully charged.

2) Balance the battery as it's being charged. This is like having the tubes running between the glasses, but you will also be filling the glasses up with water at the same time. As the glasses fill the water equalizes itself among the glasses until all the glasses are full. Then you turn off the water, or in case of the battery, it stops charging.

Battery chargers come with and without balancing capabilities. If you have a charger without balancing, you should get a balancer to do the job. This is equal to 1) above.

If the charger comes with balancing capabilities then you just plug the small plug into the charger and the charger does the rest. This is like 2) above.

As for needing any kind of switch, you really don't. The ESC has a sort of switch built into it.
The normal startup procedure for an electric plane is to:
1) Turn on the transmitter.
2) Make sure the throttle lever is all the way down (off).
3) Plug the flight battery into the ESC. You should hear some startup beeps as the ESC arms. Some ESCs require you to move the throttle lever all the way up and then all the way down to arm, some don't.
4) Now the plane is armed and ready to fly.

Glacier Girl

My Feedback: (4)

Well said Sir Raleigh. A switch is most times used in a plane where battery access is not available to plug it in to the esc to connect the system, without a lot of work.

In this type of configuration, a switch cuts the connection so no power goes to the esc/motor. This way the sytem is "dead" so to speak, until the switch is turned on.

dignlivn

Glacier Girl


You and sir raliegh both had great answers. As for the
Switch, What Amperage should the on/off switch be ??
I'm running 4s 14.4 volt lipos with a 60amp and also a 45amp
esc's. Thanks granite guy for a good question,btw.

Bob


dignlivn

Ps, I am running a 10amp switch in my 300 size heli, now
for 18 Months or so with No problems.

Sir Raleigh

As to your question about the amperage of a switch, I'd pick a switch that will handle the maximum current you plan to use, in this case, a 60+ amp switch rated at 12 volts.
As you know, switches have an amperage rating based on various voltages. As the applied voltage goes up the current capability of the switch goes down, and vise versa. Just watch the current rating for a 12 volt switch (since that's as close to 14.4 volts as the specs will get) and reduce the amperage by 2 or 3 amps to make sure get what you need.
Now, this is assuming you'll be pushing the full 60 amps through the switch. If your system actually draws less, then a lesser amperage switch will do just fine.

dignlivn

Sir Raleigh

Thanks for your help. I have only found a 30 amp switch
rates at 12 volts. Do you happen to know who sells higher
rated switches ? BTW, my set up should not pull 60 amps
constantly. I just bought the next size (amps) up than I
should require. IE: 60 amp instead of a 45 amp Esc.
Thanks again Sir.

Bob

Sir Raleigh

Let's start at the beginning...

What plane?
What motor? (with specs)
What ESC(s)? (with specs)
What battery(ies)? (with specs)

The first thing is to find out exactly how much current is going to be pulled from the battery.

Actually I've never used a switch to pass more than just a few amps. If I need to pass more current I'll have a switch operate a relay which will then pass the current.

I really need more information and then time to think about this more throughly.

dignlivn

Sir R


I'll collect that info and get back.

Bob

dignlivn

Did not mean to highjack this thread BTW.
So Sir Raleigh I'll pm you the info, if thats ok?

Bob

Sir Raleigh

No problem. I PM'd you back.

You might want to start a new thread on the subject of high current switches. It could turn out to be interesting to see what others do in this situation.

dignlivn

Sir


I just might do that. Thanks,

Bob

graniteguy

Thank you all for the information.I will keep you posted on how it goes.

Thanks Again,


Bill