Power Systems Part 2 (Class 8)
Posted March 5th, 2009 at 01:05 PM by ThursdayBeginnerBlog
Take a looky-see at our ebook here. If you are new to RC and are trying to figure out props, motors, ESCs, batteries, etc this ebook can help you out alot.
There is a good thread on Lithium battery saftey at www.RCGroups.com Just go in, scroll down some, and click on "Batteries and Chargers" and then click on the top thread called:
"Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports"
Here is a list of some decent discount servos. Best to use these if you are flying real easy without alot of crashing and intense aerobatics or flight testing. Just cruising around real easy on a Sunday afternoon is what these work best with.
- Discount Servos
- List of more Servos
Here are the servos that I use
- HS 65MG (for control surfaces)
- HS 82MG (for thrust vectoring)
Here is the BEC I use for my big planes as well. I use these whenever I'm using 7 or more servos.
Also, scroll down and see the posts below for more info!
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Comments
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More on BECs...
BEC stands for Battery Eliminator Circuit... which will probably strike you as kind of odd, because it most certainly won't work if there's no battery! In the old days, before electric flight, you had an engine, and a receiver, and servos, and the receiver and servos ran off of a battery pack. This battery was in the range of 4.5 to 5 volts or so; and usually was 4 AA or AAA sized NiCads.
Fast forward a few years, and electric planes started appearing, with higher voltage battery packs for the electric motor that drives the prop - 7.2v, 9.6v, etc. Well, you can't connect that to your 4.5 to 5 volt receiver and servos without frying them - so you needed a separate battery pack for them.
The electronics industry has had to deal with this problem since the beginning, and had a wonderful little gizmo to deal with it: the voltage regulator. Feed a high (and possibly variable) voltage to the regulator, and it outputs a fixed lower voltage.
A BEC is just a fancy name for a voltage regulator... it's called that because you can now eliminate the extra battery, and run all your gear off of the main battery that drives the motor.
Most ESCs have a voltage regulator built in that's capable of putting out about an amp at 5 volts. If you have more servos than that one amp can feed, you need to add a voltage regulator that can put out more amps - which is what a standalone BEC module is.
The tricky bit is that you usually don't want more than one voltage regulator connected to the same power distribution line - so, to use a BEC, you need to make sure that the voltage regulator's output coming from the ESC is not connected to the receiver (basically, clip the + wire from the ESC's receiver connector - but do it in the middle of the cable so you can re-attach it if you want to use the ESC later on with a different plane). Or, your BEC may have a passthrough port that you hook your ESC's receiver connector up to, and it takes care of swapping the power leads for you (no wire clipping needed); or you can use an adapter harness that's wired for it.
Posted March 6th, 2009 at 07:38 AM by hammerhead74k 
