Fuses?

[jbaur]

Hi all.

I want to add fuses to my Super Cub LP. Do I add them to the motor leads or to the battery leads - or to both? Also, what size fuse should I use.

Thanks.

[flydiver]

You DON'T want to do that.
A fuse blows, the only thing you have left is the slooooow looonnggg time to watch the crash.

If you need a fuse, you are doing something wrong. There is a reason they are not there already.

[Dillzio]

if you MUST add a fuse, you'd want about a 20amp on the motor lead. That way if the fuse does blow, you still have control of the radio/elevator/rudder. I'm really not to sure how a fuse would behave though with the current going through it at 100% but cutting in and out 1000 times a second (that's how the speed controller works).

Generally, the only thing on your plane that should be fused is accessories you've added yourself, like navlights.

[flydiver]

Jul 26, 2010 2:55:06 GMT 1 Dillzio said:

if you MUST add a fuse, you'd want about a 20amp on the motor lead.

That would be feasible and an interesting experiment. Actually some of the old brushed motors did come with fuses on the motor lead so I'm sure the ESC switching would not be an issue. In a stalled prop would the fuse or the RX/ESC blow first?
Fast or slow blow fuse? Make a difference?
Slightly higher or slightly lower than the ESC rating?

jbaur, want to try it?

[Dillzio]

I would think a fast blow that's rated higher than the ESC, you wouldn't want the fuse to blow in the ESCs normal operating range. I think we worked out once upon a time that the stock cub LP with the 9x6 prop uses 12-13 amps. A dead short should blow a 20amp fuse no problems, and hopefully save your ESC and/or battery from carking it.

If you try to make the motor spin while the prop can't turn (stalled prop) that will blow your stock ESC (know that one from experience), but with a fast blow fuse I think the fuse would blow before your ESC suffered permanent damage.

I say go for it jbaur, use a 20amp fast blow on the motor's positive lead, close to the ESC and be a pioneer!

[flydiver]

Some motor re-wind guys advocate a fuse between the motor and ESC to protect it should you end up shorting and grounding a wire while winding. There are tests to check but some are kind of complicated. Sometimes it's just easiest to see if it runs. I don't bother with a fuse, I just use a TowerPro ESC I refuse to fly but still works on the bench.