ryan_t888

Thread Title:
NEW to FE? BUILDING a boat? What's a LIPO? Look Here FIRST!

This thread had been created to assist new boaters, boaters looking to build a new boat or completely new to the electric scene.

It will replace the thread titled Choosing an Appropriate Fast Electric Setup / NON-RTR , which has over 150 replies and nearly 10 000 hits. Changes include additional information, some wording has been changed and organized sections that will be linked in a Table of Contents.
[link=http://www.rcuniverse.com/forum/m_7603257/tm.htm]LINK TO PREVIOUS THREAD[/link]

TABLE OF CONTENTS

1) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069147]THIS PAGE[/link]
2) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069153]INTRO / POWER SYSTEM[/link]
3) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069156]HULL TYPE[/link]
4) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069158]CELL COUNT[/link]
5) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069161]MOTOR[/link]
6) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069165]ESC[/link]
7) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069172]PROP[/link]
8) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069177]PRE TESTING[/link]
9) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069181]HEAT[/link]
10) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069185]DRIVE HARD.WARE SETUP[/link]
11) [link=http://www.rcuniverse.com/forum/fb.asp?m=9069192]LIPO INFORMATION[/link]

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This Thread will also continue to be updated to provide the best FE information.

Happy Boating
Ryan T (ryan_t888)

ryan_t888

INTRO
The biggest mistake a new FE boater can make when building their first boat is choosing a power combination that is not properly matched. In most cases this leads to excessive heat with in the system. Heat is electronics worst enemy, too much will certainly destroy any electrical component.

Over the last several years, the most difficult decision in choosing brushless power is KV selection. Please read through the Motor section to understand how this is done.

POWER SYSTEM
The 5 key components that make up a complete Power System in a FE hull are the following:

- Cells
- Hull
- ESC
- Motor
- Prop

The most successful order in which these components are selected is

1) Hull
2) Cell Count
3) Motor
4) ESC
5) Prop

ryan_t888

HULL
The hull is selected out of personal preference based on appearance, speed and handling goals. There are several different types of hulls.
The length of hull greatly effects speed, power handling, stability, and rough water handling conditions. A larger hull will handle more speed, more power, and be much more stable in all water conditions. This typically applies for all hull types listed below.

Mono Hull – Most common, consists of a single hull usually in a V shape. Excellent in rougher conditions, weaker in speed and handling. Easiest to setup. Balance @ 25-35%


Catamaran – Consists of 2 Outer Sponsons with a tunnel in the center section. Improved Speed, and handling, Good in rougher conditions. Typically easy to set up. Balance @ 25-35%


Tunnel Hull - Consists of 2 Outer Sponsons with a tunnel and cowl in the center section. Powered with an Out Board Motor. Good Speed and handling, Average in Rough Conditions. Moderately difficult to setup. Balance @ 25-35%


Sport Hydro – Full bodied hydro – Designed for speed/handling
Great Speed and handling, Average in Rough Conditions. Difficult to Setup. Balance at trailing edge of front sponsons.


Out Rigger – Designed for least drag. Consists of narrow center tub section with booms and sponsons offset a distance from the tub. Excellent Speed/Handling. Poor in rough conditions. Most difficult to setup. Balance @ Trailing edge of Front Sponsons or a few inches behind.


All FE hulls have a hatch. To properly keep water out of your hull, tape the hatch shut and check for leaks in the tub. Having a sealed hull will keep the water off your electronics. I use Clear Renfrew Hockey Tape. A separate radio box does not need to be used in Fast Electric Hulls. It’s a wise idea to add flotation to the hatch and the hull in case it is submerged and water somehow does make its way in.

ryan_t888

CELL COUNT
The cell count of a boat is best selected depending on the total length of the hull. Following this general chart will determine a cell count for a specific hull length while providing best speed, performance and handling for the power.

20�-27� / 55cm-68.5cm > 2 cell LiPo / 5000mAh / Min. 25C
25�-31� / 63cm-79cm > 3 cell LiPo / 5000mAh / Min. 25C
27.1�-34� / 69cm-86cm > 4 cell LiPo / 5000mAh / Min. 25C
34.1�-40� / 86.5cm-101.5cm > 6 cell LiPo / 5000mAh / Min. 25C
40.1� + / 102cm + > 8-12 cell LiPo / 5000mAh / Min. 25C

1P recommended for the smaller length in each range, low current consumption with lower kv.
2P recommended for the larger lengths in each range, higher current consumption and kv with increased reliability.

S = Series. When cells are placed in series voltage adds up, capacity remains the same.
P = Parallel When cells are placed in parallel capacity adds voltage remains the same. Paralleling packs will extend run time, increase maximum continuous draw, increase reliablilty and decrease pack heat accumulation.

This is only a general guide chart and does not mean you can’t use 8 or even 10 cell LiPo on a 35� hull vs. the spec’d 6s.

NOTE: Paralleled packs does not increase the C rating. C rating is a given rating and can not be changed. Paralleling packs doubles capacity, which doubles available constant current.

ryan_t888

MOTOR
To select the motor best suited for a hull it is important to know the hull size and amount of cell planned to be used. Size of hull will determine the size of motor needed to push the weight. Cell count will determine the wind (Kv) of motor needed.

Hulls from 20�/55cm – 34�/86cm typically will use a 540 size motor 36mm Diameter by 50-75mm length

Hulls from 34�/86cm – 40�/102cm + typically will use a motor with a diameter around or over 42mm and a length of over 60mm.

To determine the best suited Kv for a motor, the cell count planned to be used is needed. Following this chart will provide a wide-ranging base for proper kv selection.


2 cell LiPo > 3000-5500Kv
3 cell LiPo > 2000-3500kv
4 cell LiPo > 1350-2700Kv
6 cell LiPo > 900-1800Kv
8 cell LiPo > 675-1350Kv
10 cell LiPo > 550-1100Kv
12 cell LiPo > 450-900Kv

This is loosely based on an RPM range. This range is approximately 20 000RPM – 40 000RPM where approximately 30 000RPM is a decent standard for nearly all boat types. Anything higher than 40 000RPM may be considered to be a SAW(Straight-A-Way) setup and will not be covered here.

A mono hull will run the Kv’s listed on the lower end of the range. (Larger Prop)
An outrigger type hull will run the Kv’s listed on the higher end of the range. (Smaller Prop)

Higher Quality motors will run higher Kv within the range listed.
Lower Quality motors will run lower kv within the range listed.

ryan_t888

ESC
An ESC regulates the power from the batteries to the motor. It must be properly selected in order to be able to handle the current draw demanded from the motor.

It is recommended to choose a high quality ESC. The most common ESC is the HV and LV Hydra 120 by Castle Creations. For the most part these high voltage and low voltage ESC’s will handle the majority of setups. Be sure the motor selected will not exceed the maximum continuous current rating of the ESC. If it does a higher rated ESC is needed.

When using more than 4s LiPo or 12-14NiMh cells, it is wise to disconnect the BEC on the ESC and use a 4 or 5 cell NiMh receiver pack or 2 cell LiPo with voltage regulator. To disconnect BEC remove the center wire on the ESC to RX lead. It can be pushed out with a pin and replaced later if needed.

Follow motor manufactures recommendations for motor timing. If unknown, keep low. For example Neu 1D motors must always be set for low timing.

Voltage cut off is standard at 3.0v per cell. However, if the hull you are using does not draw a lot of power I’d recommend raising this value higher in order to stop a run a bit earlier leaving some capacity in the pack.

ryan_t888

PROP

[link=http://www.rcuniverse.com/forum/m_3120686/tm.htm]FOR PROP BALANCING AND SHARPENING CLICK ME[/link]


Choosing the right prop for an application is the hardest selection. Too large of a prop will certainly destroy electrical components. Too little of a prop will not get the boat on plane. It's not voltage that destroys motors, it is current and maximum rotational velocity that destroys motors. Current is controlled by the load placed on the motor.

It is recommended to seek advice if one does not know what a conservative prop would be for their specific application. Every combination is different!

Knowing which prop would work best for a hull, comes mostly from experience.

2 cell LiPo 6 cell NiMh – 30mm - 40mm Diameter
4 cell LiPo 12 cell NiMh – 37mm - 46mm Diameter
6 cell LiPo 18 cell NiMh – 40mm - 52mm Diameter
8 cell LiPo 24 Cell NiMh – 45mm – 55mm Diameter
10 cell LiPo 30 cell NiMh + - 48mm+ Diameter

It is extremely important to understand this chart is very basic, and the best or most conservative prop for any given combination may very well be out of this range.

A larger prop increases load. Increased Load will result in an increased current draw. A smaller prop will decrease current draw. Higher prop pitch will increase current draw, a lower prop pitch will decrease current draw.

Larger Props may create stability issues, make it difficult in corners and create torque steer. An advantage to using a larger prop at slower speeds is thrust. Acceleration on plane will be much greater. Efficiency is also higher for larger props as there is less possible slippage.

Smaller props may have higher levels of slippage, slower acceleration out of the hole but have several advantages. They are typically more stable handle well in corners, and don’t veer the hull of course under hard acceleration. (torque steer)

Advantages: 2 Blade vs. 3 Blade when diameter and pitch are equal.

2 Blade
- Higher Top Speed
- Less Load on motor
- Motor will turn higher RPM’s

3 Blade
- Higher thrust / Faster Acceleration
- Increased Stability and cornering
- Higher Lift Characteristics

OCTURA PROP GUIDE

12 Best used for submerged drive Setups. Low Pitch Larger diameter.
X4 are low lift general purpose props
M4 is similar to X4 but with the tongues removed to unload the prop
Y are similar to X series but have 10% more pitch
X5 are similar to X4 with medium lift and more pitch
X6 similar to X4 and X5 with medium-high lift
14 are medium-high lift commonly used for hydros
16 are high lift props for riggers and hydro's
17 are the highest lift prop for riggers and hydros
P7 are similar to 17 series but more rake and slightly less lift
19 are high lift for riggers and hydro's
V9 are moderate lift and high puitch suitable for riggers, hydros and SAW racing
20 are moderatley high lift with high pitch suitable for riggers and hydros
21 are high lift for riggers and hydro's
22 are high lift, highest pitch surface drive only good straight line speed

PRATHER PROP GUIDE

All general Purpose Props with Pitch ratio’s near 1.5 ranging from 1.5 to 1.6

Prop #-DiameterPitch
215-40.6mm-63.5mm
220-43.7mm-66mm
225-46.7mm-71.1mm
230-48.2mm-76.2mm
235-50.8mm-81.3mm
240-53.8mm-83.8mm
245-57.1mm-88.9mm
250-58.4mm-91.4mm
255-61mm-96.5mm

ryan_t888

PRE TESTING

When the hull is finally completed with a well suited power system it is very important to follow these next few steps.

After choosing the most conservative prop for a given setup, charging the packs and placing the hull in the water run it for 45 seconds. After the 45 second period, bring the hull in and note the temperature of the ESC, motor, and cells. If all components are well under 140F/60C, run the hull for yet another 45 seconds. If temps are under spec run for another 45 seconds and continue this pattern.

If the temperature exceeds the safe limit, one has either exceeded the maximum allowable run time or is using too large of a prop or a combination of both. Reduce prop size or run time.

Following these simple rules will greatly increase the odds for a successful 1st or 100th run.

For even greater safety, make only a few passes totaling 20-30seconds and bring the boat in. Checking temperatures can be a pain but will save loads of money

ryan_t888

HEAT

There are several reasons equipment may heat up, if this is the case here are possible causes. Too hot - greater than 140F/60C. Many times there may be more than one reason for over heated equipment. In this case choose the most logical fix.

Motor - too hot
Possible Causes
- No thrust bearing, creating extra resistance when thrust is applied
- Binding within the shaft. When the motor is disconnect, rotating the prop shaft should be done effortlessly
- Too much prop
- Too much run time

ESC - too hot
Possible Causes
- ESC not properly matched to motor - exceeding continuous current limit. A larger rated ESC is needed
- Too much run time

Cells - too hot
- Drawing too much current from the cells. Increase capacity or C rating. Only use a maximum of 80% of the calculated max discharge rate
- Too long of a run time. Be certain to not dump the packs or hit the Low Voltage Cutoff


If all components are running less than 60C or 140F, your setup is sufficient.

I also like to use a Data Logging device to record what my system is using in terms of power. The product I use is the Eagle Tree Data Logging unit. I can graphically see the amount of current I am pulling during constant throttle while the boat is near maximum speed. I can also note the peak current pulls that happen during acceleration of the boat. Although these are higher and sometimes significantly higher, these peaks only last for a few short seconds. The watts up meter, different than the Eagle Tree, will hold these values in memory and may miss-lead you when you view your system is pulling a significant amount more than it actually is.

ryan_t888

Drive Hardware Setup

There are two types of outdrives that are commonly found on RC boats. These include the Stinger outdrive and strut drive. Stinger drives are usually only found on mono hulls. They house the prop shaft completely from the transom to nearly the prop. This provides a unique appearance to the hull.

A strut setups is more commonly found on all hull types. This holds the prop shaft usually a set distance away from the transom.

The drive dog is used on the prop shaft to transfer power from the prop shaft to the prop. There are different sizes for each shaft size. Select the one that works best. The distance between the drive dog and strut/stinger should be the thickness of the cable. If you are using a .187� size flex shaft keep the distance between the drive dog and strut/stinger to .187� or 3/16�
Flex cables shorten when under load. This set distance will allow the flex cable to shorten and not wreck havoc on the motor, strut or create extra drag from binding. Keep in mind this will never be seen on the bench, it only occurs when the boat is running in the water.

Flex Coupler. This component couples the flex shaft to the motor shaft to transfer the power. Also known as Flex Hex. It is wise to place a thing coating of solder on to the flex shaft in the area the flex coupler will hold it. This maintains a nice snug grip while not separating the winds from the flex shaft.

Stuffing Tube.

The stuffing tube supports the flex cable shaft. It provides the shape the shaft will follow. It should be placed as close to the motor as possible and usually goes right inside the strut or stinger. The stuffing tube in some cases house a Teflon tube which also is used to support the flex cable.
The stuffing tube can be made out of K&S tubing with sizes as follows:
Stuffing tube Size when used with Teflon tubing.:
3/16" tube for Octura .098 Teflon tubing.
7/32" tube for Octura .130 Teflon tubing.
1/4" tube for Octura .150 Teflon tubing.
9/32 tube for Octura .187 Teflon tubing.
11/32 tube for Octura .250 Teflon tubing.

Stuffing tube sizes when used with out Teflon tubing:
5/32" tube for Octura .098 Flex Cable.
3/16" tube for Octura .130 Flex Cable.
7/32" tube for Octura .150 Flex Cable.
7/32" tube for Octura .187 Flex Cable.

ryan_t888

LIPO

It is highly recommended to use high capacity cells with C ratings of 25 or higher.

Using LiPo batteries are as simple or more simple than using NiMh cells. As long as manufacture warnings and instructions are followed use of LiPo is very safe.

Charge LiPo's at the rate specified by the manufacture. In most cases this is 1C.
C = capacity. A 5000mAh pack would be charged at 5.0A - 1C. In some cases LiPo’s can be charged at faster rates but this must be specified on the LiPo

All LiPo cells are also given a C rating. This C rating is specific to the maximum rate of discharge the battery can perform safely. The recommended maximum discharge is calculated using the C rating and battery capacity. A 25C 5000mAh battery has a max discharge of 5Ah * 25C = 125A. I would recommend drawing at most 60-80% of this. 60-80A

Long LiPo Life
To ensure long life of cells:
- Try to avoid getting them wet. Although the cell is completely water proof, the balance taps are not and can easily corrode from excessive water. If a pack becomes wet one may cut the shrink wrap off, dry out the taps, and re-shrink the pack.
- Discharge a maximum of 60-80% of the spec'd maximum discharge rate. Running 2P will greatly take the pressure off the cells. This is depandant on C rating and capacity.
- Discharge the cells to the manufacture specified voltage when storing. This is typically around 50% capacity.
- Only discharge a maximum of 70-80% off the cells total capacity. This means bring the boat in well before any voltage cut off kicks in. Or increase the cut off to a higher voltage using ESC programming tools/software
- Avoid temperatures higher then 60C or 140F.

keithbradley

My Feedback: (38)

Thanks for the great thread Ryan.  Lots of good info.  How about posting your method of estimating how fast a given setup will be?

ryan_t888

If I get around to it, I'll make a Calculation Post and add it in. I'd have to try and simplify the formula if I decide to post it for the estimation, as it is very long.

Ryan

telleslattari

congratulatios ryan!
this topic i`ll be my inspiration to finish my catamaran 1 m long
thank you a lot.
i`m learning here to realize a kid dream...

thanks
leo

wave waker

very nice of you for taking your time sharing your knowledge and concern to fellow boaters! more power to you..[sm=thumbup.gif]

srt10

My Feedback: (20)

Love the posting!
great info for others to follow..

iceman0

Thanks fo rthe writeup cleared up some questions.

tonywayne

great thread

ryan_t888

Thanks for all the comments guys. Glad people are reading it and finding it useful.

Ryan

moparmagiclives

Very good info, you have helped me with a smaller boat i'm building but this will be very helpfull on my vegas conversion I'm starting.

Slowjohn

Thanks for all of that info big time[sm=thumbs_up.gif]
At least I now know I'm pretty much on the right track with my Miss Vegas conversion. What I need to know at the moment is where I can get the coupler I need for the 5mm inrunner motor shaft? The boat had a .18 size glow eng. to start with so the eng. end of the coupler is for a threaded shaft. The boat was given to me and since all of my planes are lipo powered I figured I'd go the same on Miss Vegas.
I'd appreciate any & all help especially if anyone can point me to a conversion like I'm doing.

Thanks
&
Standing By,
SJ

ryan_t888

For all parts check offshorelectrics.com. Your coupler should be there. Be sure to choose the correct one based on the diameter of your flex shaft.

Thanks for the comments

Ryan

Slowjohn

Thanks a lot Ryan,
I have a couple of Grandsons who're gonna enjoy this so much. They love to go flying with me and get so disappointed when I tell them the wind is blowing too hard to go flying so I figure the boat will fit in nicely & keep them happy.

SJ

ryan_t888

Good luck. I would suggest creating a thread on your project and goign over the specifics of your setup just to confirm everything will work properly.

Ryan

Slowjohn

Sounds like a good idea. Once I've got everything I think I'll need to put it together I'll start a thread. I've got way too many unfinished planes sitting around in various stages of completion due to not having everything I needed to start with to finish and since there's not a close LHS I order everything online. If I have to wait more than 2 or 3 days then I start another project

Standing By,
SJ