Brosol Brosol Thread OP

Quote: mvadu Originally Posted by



http://www.mouser.com/Circuit-Protec...z0rvz5Z1yzvhll Wov!! good stuff man.. I am just waiting for my v911 to arrive, and could only hope to do some if not all the mods you have done. For fuses, try one of these PTC fuses, they are straight solderable, easy to get, and dead cheap.

Thanks man. Regarding PTC fuses:





Quote: RicksterRC Originally Posted by By any chance has anyone measured the max current of the main and tail motors?



EDIT: Answered my own question.



I have a Corter with a dead RX board (burned FET) - I'm looking at getting some fast PTC fuses to protect things.

I'll keep people posted.





Tail rotor:

Tested 100% Full Bore Across battery (bypassing FET)

Free .7A.

Stalled 1.1A



Main rotor:

Tested 100% Full Bore Across battery (bypassing FET)

Free 1.1A

Stalled 2.2A (and not happy - smoke from somewhere, maybe windings, maybe board traces).

Quote: RicksterRC Originally Posted by My search turned up nothing that will work.

As you suspected, unless you get a WAY overcurrent (10x or so), they take forever to trip.

They are to be used for short circuit protection, not locked rotor (which "only" doubles or triples the current. At double the rated current, the "0.2S" ones take 10-120 seconds... the FET is long gone by then.



Even normal "fast blow" fuses take a while at only 200% rated load.



I have some current/temp protected FETs on order from Digikey (NIF62514T1G)

They are not dropins (they are larger), but I'm going to try to ue them to fix my RX and see if they are a good solution.



If anyone knows of a temp protected drop in, please let me (and WL) know!

Quote: RicksterRC Originally Posted by

I was looking for a 2A "thing" that would protect the FET during a stuck rotor.



I had high hopes, but they were dashed when I spoke to the Littelfuse rep.



I was discussing:

Rated 1.25A continuous, 2.5A trip, 0.4s/

Turns out the 0.4S is if you pull 8A.

The graph looks like 2.5A would take around 20S.



She said that their parts are designed for power supply shorts.

Current magnitudes higher than normal.

Double isn't doable might not even trip.

5 times would probably trip, but take a long while.



After research, I think the part in this link:

is this part:



It's a 3A part. It's not rated to trip until 6A.

If you pull 15A, it takes 10.8 seconds.

If you only pull 6A, the graph looks like a bit more than 30 seconds.



Motor lock is never going to trip this.

A short in your batter cable might, though our 20C 120mAH batteries probably can't put out 6A before catastophic meltdown.



If you've got a high cell pack that can put out 100A if shorted, this might be a good addition.

If you're trying to protect your V911 FETs and/or botor brushes, I don't think it's the right solution The main rotor draws around 1.1A normal and twice that rotor locked.I was looking for a 2A "thing" that would protect the FET during a stuck rotor.I had high hopes, but they were dashed when I spoke to the Littelfuse rep.I was discussing: http://www.digikey.com/product-detai...9CT-ND/2498895 Rated 1.25A continuous, 2.5A trip, 0.4s/Turns out the 0.4S is if you pull 8A.The graph looks like 2.5A would take around 20S.She said that their parts are designed for power supply shorts.Current magnitudes higher than normal.Double isn't doable might not even trip.5 times would probably trip, but take a long while.After research, I think the part in this link: http://www.horizonhobby.com/products...bcx-2-EFLH1206 is this part: http://datasheet.elcodis.com/pdf/22/.../30r700umr.pdf It's a 3A part. It's not rated to trip until 6A.If you pull 15A, it takes 10.8 seconds.If you only pull 6A, the graph looks like a bit more than 30 seconds.Motor lock is never going to trip this.A short in your batter cable might, though our 20C 120mAH batteries probably can't put out 6A before catastophic meltdown.If you've got a high cell pack that can put out 100A if shorted, this might be a good addition.If you're trying to protect your V911 FETs and/or botor brushes, I don't think it's the right solution Quote: asanado Originally Posted by You can just put a simple and cheap smt/other fuse (with socket)... and replace it when burned. It costs only a few cents, and if your calculations are right, you can choose the correct Amper value and response from a wide range.

You are not supposed to burn a fuse every 5 minutes, it will happen once a week (worst case) if you are pulling your throttle down before crash - so costs will be minor.

The V911 FETs are somehow more durable then the Solo Pro ones. I had more severe crashes with my V911 and never burned a FET. WIth the Solo Pro I have already burned three.

Its my understanding that PTC fuses would be too slow to react to protect Rx MOSFET and motors from overcurrent damage.



It was suggested to use fast blow fuses for overcurrent protection with brushed motors.



I'm using fast blow 1206 fuses. Thanks man. Regarding PTC fuses:Its my understanding that PTC fuses would be too slow to react to protect Rx MOSFET and motors from overcurrent damage.It was suggested to use fast blow fuses for overcurrent protection with brushed motors.I'm using fast blow 1206 fuses.