Stiletto Race Prep

[jasoncyclone]

I added the cap. It was a 60 amp proboat esc.

[SkipJack]

Well, I have never seen a schematic of an ESC yet but I worked as an Electronic Engineer for 15 years in Silicon Valley and I have seen a lot of power units. Some take the DC input and create an AC waveform that is then Pulse Width Modulated, called a chopper stage, that can be cut on and off so the total effective power is controlled. Other things happen in the middle stages like timing and then the output drive has to match the poles of the motor like 3 phase motors we have. This is not the place to go into details but the values of a capacitor are usually made on two considerations 1) Voltage Rating and is usually twice the voltage it will be exposed to so for 14.8 input stage you would want about a 30V part but to be cheap they may have shipped with a 25V part, internally the voltages may be as high as 100V so the internal caps could be rated as high at 200V; and 2) Capacitance and this is based on how it is designed to work with other components for filtering, wave shaping, and possibly in a network to prevent back-EMF from letting spikes hit the battery or the control signal output from the RX. A chopper power supply is very noisy electronically and has to be designed also to limit the RF that would disturb the communications signal as well. So when you say you added a cap, What are you talking about? I am left clueless as to what it improves and if you are not replacing one for a higher voltage rating what are you talking about? THX and sorry about the long message. I have posted this question on other forums and I have gotten directions on how to build a necklace, LOL. Thanks for some clarity, I am open to learn everything I can about RC and EP!

[jasoncyclone]

I am pretty new to the electric boat world. If you do a search in this forum about adding caps you might find the answers you are looking for. I just know that a cap take the main voltage spike and are what usually fails first on the esc. You will not be replacing the caps just adding more caps. If you go to the OSE shop and look at the esc section you will find extra caps for sale. I just installed a 35v 1000uf cap on my 60amp esc. All you do is take the two wires from the cap and solder one cap lead to the positive wire on the esc and the other cap lead to the negative lead on the esc. If you do a search you will find tons of info from guys that are alot smarter than I am giving how to's on this topic. I hope this makes sence to you???

[SkipJack]

Thanks, I saw the caps for sale and I read something on one of the threads about the top of the caps puffing out from over heating or abusive operation and they had to replace them but I hadn't read anything recently about adding them; completely different than Lipo's puffing, another $$$. I thought you probably meant putting the cab across the power leads from the battery, but I wasn't sure. This would make sense to stop spikes from hitting the battery, kind-of like an input filter, sometimes a zener diode of the right spec can be added too unless it already has one internally. Also, a lot of older electronics would die quicker from hot-plugging things and since we have no on/off switch we are kind-of hot-plugging when we connect the battery to the ESC. Even static electricity can be on our boats and right before we make a complete connection a spark can hit the ESC. Thanks, I am happy you got back to me. I am always open to learn as much as I can and will share if I can!

I got some additional info from another forum, getting off topic but I guess the older brushed motors caused problems for the AM / FM radios of the day so it was common to add caps to cut down interference. I am also assuming that the older the brushes get the more interference they cause.

It is a beautiful and sunny day here in Florida...

[sailr]

Adding caps is to suppress the ripple current, the spikes between when the boat jumps out of and back into the water...creating instant heavy loads on the esc. The capacitor(s) will absorb the shock (ripple) and thus smooth out and save the esc!

[giddyuperic]

Hello guys and maybe gals. I am going to run another water pick up for my 120amp ESC and let the stock one just cool the motor . Can some show me or tell me the best place to mount the pick up on the transum? I was going to put it to the right of the out board maybe a 1/2 " or so does that part stay in the water? And help would be great. I going to run the out put from the motor right coming out of the case and then the ESC I need to put the pick up on and then it can just come out of the old tube it came out of before.

[giddyuperic]

Hello is this thing on!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!

[SkipJack]

Most of the outboards I have seen, the water pickup is behind the prop on the outdrive. I believe if you mount it on the transom the pickup tube will come out of the water when you are flying on a plane. If you mount it anywhere on the hull, e.g.; on the back of one of the sponsons I think it will effect the handling of the boat. I would guess you could drill a hole on either side of the existing pickup tube and run a brass tube externally on the outside of the outdrive and then ? take it from there.

Hope this helps, if this is what you were meaning?

[giddyuperic]

So the whole trasom is out of water when running? I would think there would be some part of it still in the water when running? There was a guy on this thread who added a second water pick up but I can't find his post. Thanks for your time.

[SkipJack]

Well, I took my new boat out of the box, they sure did a good job. I ordered batteries from HK so that is like waiting for water to boil with a cigarette lighter.

I have plenty of time to race prep the boat but unfortunately the bullet plugs are coming with the batteries so that is one thing I can't do yet.

I have read all the stiletto posts I can find so it seems weird that the ESC manual says the unit ships pre-programmed for Ni-MH with brake on in soft timing mode with a linear throttle curve; and also says

"Caution: It is imperative that you do not attempt to use LiPo batteries with the ESC unless it has been properly programmed or serious damage to the batteries and electronics may occur due to over discharging"

I will keep everyone advised how it goes... Maybe someone can shed some light on this?

I went back and found on post #64 that the ESC is programmed at the factory for LiPos


Maybe if you only buy the ESC, then the manual is correct but if you buy a complete Stiletto Boat then they reprogram at the factory? See what I get for reading the manual, LOL, more confusion?

Update: I ordered a battery from a US source so I will find out if it makes toast or boils water in a few days...

THX, Harry

[Mel279]

I also wanted to add the ability to oil the flex shaft without taking it out. So, I pulled the lower unit apart, and replaced the teflon with a new stuffing tube made of brass.

To bend the brass, which is right at .187ID, I slid in a .187 flex shaft, which JUST fits, and carefully and slowly bent it around a mandrel to shape. I had lightly anealed the brass first.

Once I had it bent to fit, I drilled a small hole near the back of the top, and soldered on a 5/32" tube for a fitting. I will simply attached some larger sized water tubing to this, which will allow me to use a syringe to inject oil into the flex shaft. I'm going to exit the tubing out the back of the outboard so I can service it without taking the cover off.

Once you have the stuffing tube built, mark the placement of the oil tube on both halves of the outboard and grind/file the material away at this point.

Darin

what's the size of the brass tube you use to replace the teflon tube?

[sailr]

I replaced the teflon on an O.S. unit and picked up considerable speed and reliability! I didn't put in an oiler though which is a good idea.

[Darin Jordan]

Darin

what's the size of the brass tube you use to replace the teflon tube?

I'll need to go back and look... I THINK it's 7/32"... but I'll have to look again. It's been awhile since I've done it. That would give you 0.190" ID, which sounds about right...

[Proboat]

Is there anyone or anyplace that I can buy a pre-made oiler tube from?

[Proboat]

Darin,
You have commented a few times that you would hold off on recommending what prop to use on a stock Stiletto. I can't seem to find what prop you recommend for this boat.