RCU Forums - RC Surfer

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- - RC Surfer (https://www.rcuniverse.com/forum/rc-boats-general-discussion-77/5503299-rc-surfer.html)

Yeah, LiPo's rule, don't they ? I use them in all my RC stuff except my Amphicar ( need the weight from NiMh). If you treat them well they will give you no problems. And power-night vs. day !! Do you think you will ever try 11.1 volts, does it work fine on 7.4. Maybe 11.1 is overkill?

7.4v seems fine.
I don't know about 11.1v.
If I found a hard case with 4000+ mAh that fits???
Well, I would like to try one.
But yes, 7.4 is great for the NQD.
Blew my mind.
Once the surf gets too powerful the NiMh don't cut it and weigh too much as well.
My board seemed to surf fine with the lighter packs with no adjustments to the ballast configuration I am using.
It may change over time.
JIMI (LiPo Powered & Stoked)

Hi guys,
ESC started playing up on second pack.
Opened up and it was crackling.
So do I need a bigger ESC to handle the power of my new LiPo's?
I only have a 60A Seaking.
Seb, Help???

Also,
I have proof chicks can surf too.
Check out the pic of Jazmine Fawcett at Kalbarri.
She is my photographers daughter.
A Real life Lisa!!!
This place is Very HEAVY Dudes.
I don't think I will be RC surfing there.
Sea Ya Guys.
JIMI (Gero W. A.)

Hey Jimi,

The 60A Seeking ESC is a great and hassle free ESC as long as it stays BONE DRY!!!If you get it wet, they will start having problems. I have bought about 5x60A, 2x90A and 1x120A Seeking escs and they have all performed flawlessly until they got wet. I have flushed them with WD40 and RP7 when they did get wet and have let them dry and they have worked again but they will die or give you problems in the near future.

If it is not because it got wet, then check the solder on the ESC. If the plugs were not soldered properly, they can start to separate and that can cause problems.

It may be the battery, so check the battery plugs and see if the solder has melted. The solder will melt if it was not soldered properly and the soldering iron tip was not cleaned during the soldering process.

Sometime if the battery has got wet or just damp inside the surfer, the wires can start to rust orcorrodewhich will cause problems, however your batteries are new so this may be unlikely as it could only happen if your surfer got flooded. I do my own soldering and I re-solder plugs i feel may have problems. It has on numerous times fixed the problem.

It is not because your batteries are of a high ampage. Your motor draws a maximum of about 55A during bursts, so a 60A esc will work fine. You can run a 1000A battery (if such a thing existed) through a 60A esc and it will only draw through the esc what the motor needs. I run 11.1v 30A 5000mah batteries (200A burst rate) through a 60A esc using a motor that draws 54A and have had no problems. I have even used the same battery and esc to run a 540 Large motor in my big surfer that draws well over 60A and have had no problems. I know first hand the 60A esc will handle more than just 60A, the manufacturers put a rating of 60A to cover their asses. So I am sure the problem it is not because you are over loading your esc.

These ESCs are fairly cheap, so I always have a spare ready in the event a water pipe comes loose inside the board or if I forgot to do up a deck bolt. Yes, I have done this before..... I am human!

Another solution is to fill the ends of your esc with silicone. Silicone is non-conductive and will stop any water getting in. However, silicone will eventually deteriorate so keep an eye on it if you do.

About your lipos, turnigy are good batteries at a great price! I get mine off hobbyking for $26US each, with the exchange rate being almost 1:1 to the US dollar, they are very good value. I enjoyed the 7.4v lipos, they kept the board light and helped the surfer self right well. When I switched to 11.1V 30A 5000mah lipos, my first thought was this isridiculously fast. However, I have learnt not to be trigger happy and it surfs very well and I can get out to the lineup 80M out in seconds and do airs that are unnatural (hit the lip of a 3 foot wave at full speed and you could jump a two store house, i'm seriously not joking) and i get run times of up to 25 minutes of non stop surfing. Eventually you will move to 11.1v, it's just evolution, and you will be just as blown away as you were when you first got onto lipos.

Anyway, check the solder on your plugs and let me know if you still have problems.

Seb.

Hi Seb,

Are you able to charge your 11,1V-LiPos from your car battery (12V) or do you only charge them at home?

THX for any info
Rainer

Rainer,

If your DC charger has the large crocodile clips that connect to a 12V car battery then yes you can. However, a car battery is only about 7000mah, so if you try and charge a second battery, your car will probably not start ; )

If your charger takes an AC adaptor, then spend the 20 bucks and buy one off eBay, much less hassle.

There are lots of cheap lipochargers with balancing on eBay from China. They are fine. I have bought two and they have lasted years and charge up to 5A which is normal as you DO NOT charge your lipos more than the amps. For those who do not understand amps or currents, I will explain below with what i have learnt online. I hold no responsibility for any false information, i'm just passing on what I have read.

Battery example:

7.4v 20C 4000mah.

When a battery says it is a 4000mah battery, it means it is 4amps.

The 20C means the current. is times 20. A battery at 1C will discharge in one hour at full throttle.2C will discharge in 30 minutes, 3C in 20 minutes.Dividethe #C into an hour.
So a 20C battery is able to be discharged in 3 minutes. No this is where it gets confusing..

The battery above is 20C, to work out itscontinuousdischarge rate, we times 20C X 4000mah (4000mah = 4Amp. Mah ismilliamp) So we get a 20C x 4Amps = 80Ampcontinuousdischarge. If your motor is rated at 80A and your battery is 80A, at 20C you will discharge the battery in 3 minutes at full throttle. If the motor only draws 40A (half the amps) then it will last approximately 6 minutes. You all get longer than 3 minutes at the beach as you do not go full throttle for the entire time.

Now the 7.4v has no impact on the aboveequation, it is just the rotation power of the battery. But this is where volts come in to play.

A motor will rotate 33% more with a 11.1v than to a 7.4v at full throttle. So in effect, you use 33% less power to do the same speed as a 7.4v would using a 11.1 battery or at full throttle you will go 33% faster. However, 11.1v batteries ate also 33% bigger...

Us RC Surfers (excluding those who make their own and require much bigger motors and ESC with greater capacities) will use a motor that spins at approximately 3000rpm/v motor. This motor can draw 54A max.
Now we all use an 60A ESC, which is appropriate for our needs.
Our choice ofbatteriesdiffer, however, those on lipos will probably be using around 7.4v 25C 4000mah batteries as they will fit in the space for the battery without cutting out the battery area.

This means:
The motor will rotate at around 21,500 time per minute and draw at a maximum rate of 54A at full throttle.
The battery has acontinuousdischarge of 100A
The ESC can handle only 60A, but this is ok as the motor will not draw more than 54A and your ESC will not blow up. If you were to run a motor which draws 100A on a 60A ESC, then your ESC will heat up and go pop and a small puff of smoke will come out and you will have to buy another ESC.

Props.

A prop with a higher pitch will put more strain on the motor. We all use around 30mm props with a pitch of around 1.4". This is good as the motor can spin the prop effectively without over heating, or spinning too easily which will waste power and push our surfers that weigh around 1.7-2kg. A motor loses efficiency the hotter it gets. If you have a good cooling system, your motor will perform better, if you do not the motor will heat up and become less effective. If your motor is running hot after a surf, then i suggest either installing a better water cooling system, reducing the size of your prop, of reducing the weight of the surfer.

Electric RC is complicated. You always need to take into account the motor Amps and rotations, the ESC amps, the battery Amps, the size and the pitch of the prop and the weight of the object you are moving. While there is no straightequation, it is best to use what is recommended by those who have trieddifferentconfiguration.

People will often recommend to have a motor and battery that draws and discharges an ampage rate lower than the ESC rating, but as we all use batteries that are rated higher than 60A and we all use ESCs that are rated for up to 60A, this is not a problem. Just always make sure the maximum rate at which a motor will draw amps is below the Amps of the ESC.

CHARGING

Now with charging your lipo battery, always charge it at the same rate as the amps. So if your battery is 4000mah, charge it at a rate no higher than 4amps. For a 5000mah battery, no higher than 5. Now remember lipos lose their punch after a while so when you battery starts to charge to 3500mah, lower your charge rate to 3.5A. I always charge mine .5 below the rated level to make sure i do not damage any of the lipo cells.

I know a lot of you out there reading this already know this, but i wanted to know this a couple of years ago and i really had to search elsewhere to find the answers, so those RC Surfers who were not sure will now know.

Hope this was helpful.

Seb.

PS. I don't write too often here so i think this long explanation gives me a week or two off from adding material ; )

Forgive me for any typos above, I was typing as fast as I was thinking and I can not touch type....

Hi Seb,

Impressive explanation - thanks a lot!

Never mind - my car battery has got approx. 70.000mAh (Diesel engine ;-))

But I'm still not sure about the over-voltage you need to charge11,1V-LiPos with a car battery of 12V:

When I'm charging my 7,4V-LiPo my charger (Graupner Ultramat 16)uses approx. 8,3-8,4V charging voltage (= over voltage).

Applying rule of proportion I would need 12,5-12,6V to charge 11,1V-LiPos.
But a car battery only supplies 12V - rather less than 12V under load.

That's why I'm asking:
Has anyone of you ever charged 11,1V-LiPos using a 12V-car battery as the power source??

Thanks for any info!

Take care!
Rainer

You'll be fine.

The DC amps from the battery is only 12V and you are charging a 7.4v battery. The charger (If it has the clips that connect to a car battery) will convert internally the 12v to the voltage set to charge a specified battery. The input can take any voltage between 11-16v from DC power (car battery is 12) and convert it to the voltage required to charge the battery.

The AC adaptor which runs from the mains power to the charger converts the input power from 220V to 12V and the charger takes over from there. So connecting it to a 12 volt battery will supply the charger with exactly the same voltage as theadapterfrom the mains.

Do not connect a car battery directly to the terminals of a lipo battery or you will experience exactly what happens when a lipo explodes from being over charged.

I have attached a picture of a charger like mine. If you have the battery clips like the ones shown in the picture then you can charge from a 12 car battery. It has these clips so you can charge lipos from your car battery at theairfieldif you are flying electric planes.

Does that answer your question?

Thanks Seb,

I just learned from another (German) forum that my charger is able to increase the 12VDC input internally to higher charging voltages.
I'm deeply impressed! ;-)
So, 11,1V LiPos are no problem.

Anyway, thanks for your reply!

Take care!
Rainer

Guys

what charger and lipos do you recommend? Idon'tmindmodifyingthe battery compartment either if its worth theperformance.
I'vegot Seaking 3600 and 60amp esc.

LiPos:
Turnigy 7,4V 4000mAh
http://www.hobbycity.com/hobbycity/s...dProduct=12932

Charger:
Graupner Ultramat 16
(However, this one might be difficult to get outside Europe/Germany)

Take care!
Rainer

Cananzi,

Call me and I will explain everything. I don't feel like typing everything out.

Seb

Cananzi,

You bought it as a combo, so it will be fine. Just reduce your prop size as your motor isgoingto have less torque and more rotations than a 3000kv motor.

Goodluck.

Thanks for all the info Seb.
JIMI

Ran 4 Lipo's today in average and pretty destructive conditions ESC seems fine.
Carbo Dude is holding up to some extreme slamming.
Still having minor issues to resolve.
Small amount of water getting in up front and around prop shaft/coupler.
Never ending process of elimination.
Kept having intermitent loss of half power.
Not sure why yet.
Board needs a thorough strip and clean again.
What great fun.
Did get a few good waves.
JIMI

Hello,
Stripped, cleaned and rebuilt this evening, RTR again.
Had to replace a coupler and prop shaft.
Got that hot the other day when the grub screw came loose, it is stuffed.
Couldn't get rid of the motor bounce 'till I put a new one in.
All set to go now.
Phew, these little machines are a full time job if you hammer 'em every day.
I LOVE IT!!!
Lipo's are CHARGIN", Yahoo..........

Have Fun Guys.
Sea Ya.
JIMI (Geraldton, WESTERN AUSTRALIA)

Jimi,

I'm thinking i'm going to come live in Geraldton, the surf around here has been absolute crap, and you seem to get awesome waves everyday! Actually IGoogleEarthed your area and there are heaps of spots to go surfing.

I read your last post and you said your motor was bouncing, was that because you couldn't align the coupling and shaft perfectly? This is what killed my first board. The bouncing motor eventually broke the small pieces of plastic that the motor mount screws screwed into . After that the board was useless. That is when I decided to open the board up and investigate.

While i separate all my boards now and silicone them, I also put a huge amount of epoxy around the pieces of plastic that the motor mount screws go into from inside the board as i don't want them to break ever again.

I really suggest moving to a shaft with a flexi end and a coupling designed for it. They cost about $30 for both items but the vibration will never occur and motor will never bounce again and removing the motor from the coupling to re-grease the shaft is a 2 minute job max and only needs to be done about every 5-7 sessions. It was the best rc surfer investment ever. Giving the amount of time you use your surfer I would hate for you to experience what killed my first board.

Below are two links to the items.

<a href="http://cgi.ebay.com.au/rc-boat-5mm-x-3-18mm-collet-/370352023837?pt=AU_Toys_Hobbies_Radio_Controlled_V ehicles&hash=item563ab3691d#ht_1175wt_905">http://cgi.ebay.com.au/rc-boat-5mm-x...#ht_1175wt_905

http://www.cornwallmodelboats.co.uk/...ex-shafts.html </a>
Check it out.

Seb.

Thanks Seb,
That is my next mod I am intending.
But I will do it on a new hull and go all the way with the seal and everything.
The bounce was caused by the metal getting so hot from the friction and turning black and a little bit of smoke even.
Once that happens the coupler propshaft never aligns again.
On my old board this caused the motor mount to crack into 3 pieces and also a second motor mount that I used.
I replaced the coupler and propshaft and it is nice and straight again. No more bounce.
I will be eventually changing to the flexi coupler but not sure when as I have two other brand new hulls that already have the tube stuck in and don't don't want to remove them again.
So I guess I will just use my current setup for a while untill I have had enough of the hulls that I already have.
When I build another one from scratch I will be sending you a zillion questions so that I can seperate the hull and also do the flexi thing.
I think the combination of your hull and flexi setup with John's "Surfcurls" gear that I use and my own personal modifications will definately result in a great RC Surfer.
Thanks for sharing all your knowledge, it takes a lot of hours trial and error to get these things consistently reliable and performing at the highest level in real surf.
You are a master of the NQD and I hear what you are saying Dude.
Come and live in Gero, there is lots of work here and the surf is perfect for your surfer girls.
JIMI

Seb,
I just had a look at the gear.
Which propshaft do I need?
Tell me and I will order a couple.
Didyou cut and shorten the coupler, it looks like you did in the photo you posted a while back.
How hard will it be for me to take out the tubes I already installed and replace them with these?
Will the coupler fit to my motors?
Tell all Bro.

JIMI (RC SURFING HEAVEN)

Jimi,

It takes about 20 minutes to fit one and that includes the time it takes to for the epoxy to set....

You want the 146mm shaft (16mm flexi insert, 130mm shaft) The shaft is 4mm, the tube is 6mm and the flexi end is 3.2mm.

The flexi coupling is for a 5mm shaft end and a 3.2mm flexi end. You can get different ones for different size motor shafts.

The flexi coupling is a fraction longer than the solid coupling, so you need to get a drill the hole where the prop shaft comes into the board compartment with an 8mm drill bit, make the hole bigger and clear away some of the Chinese epoxy.

You don't even need to epoxy the end on the shaft that comes into the board, only the end nearest the prop, it is seriously that smooth.

You will never need to buy another coupling, maybe a shaft once a year, but that's it. And no more broken motor mounts or the plastic where the motor mounts screw in. And changing motors to re-grease shaft is a 2 minute job.

I wouldn't recommend it if i didn't think you would be blown away by the difference and smoothness.

I have attached three pics for you to see what i mean in regards tomodification. It is very simple. And to remove theprop-shaftyou have already fitted is a 30 second tasks.

Deliver from the UK is about 6 business days.

Thanks for the invite to come live in Geraldton, if the weather continues to be crap, who knows....

Seb

Seb,
Why does the coupler in the board only have 1 allen key screw and the one in the photo on its own has 2?
That is why I said it looks like you had cut the coupler shorter.
Oh God, I know I have to do it but am a bit apprehensive.
I just know it is the next step and it has to be done.
More work.
JIMI

If this is a bit complicated and you want to stick with your prop set up thats cool, maybe later.

Flexi coupling doesn't need to becenteredlike the solid couplings do, which is why I will never go back to them EVER!. The grub pushes against where the motor shaft is flat. The other end twists tight against the flexi coupling.

With flexi- shafts, your motordoesn'tneed to be inline with the prop, hell it will run smoothly with the motor at a 45 degree angle to the propshaft, thats thebeautyof these shafts!

The reason one of my couplings has 1 grub and the other 2 is because they are from different manufacturers. The grubs only screw against the motor shaft on one side. The one with two grubs I use on my big rc surfer.

If you look back through this forum you will remember a couple of months ago I said you need to switch from NiMH to lipos, and now that you use them, you are like WOW..... Well this is another one of those moments.

Seb

hey guys

Bad news!!! finish work late so i had a heat gun going last night to dry paint faster, it was sittingprobablya good 3 metres away and it slightly warp my board!! n0o0o0o0o0o0o0o0oo0o ...extremely soft plastic!! crazy.Iwouldn'tof thought it would of been that hot from that sort of distance but obviouslyIwas underestimating my heat gun lol Oh well LUCKYIbrought 2 boards.

Had to started from scratch!. Ripped everything in to pieces. It was so easy pulling the a board apart the second time! got the shaft out no problems ,drilled small holes in the china adhesive and it pop straight out . Epoxyed about 100grams of weight in the board and sealed her up, i think i might epoxy a layer of cloth on the seams to be safe.Ordering a couple of flexi shafts and couplers that sebrecommendin earlier post, thought Iget a few spares. Transmitter arrived today 2.4ghz venomcheapy,hopefully that will do the trick.

guys where do you get the small copper from for the water inlets? Irealisedthat the other stuff I got was slightly to big anyway.I'vetriedair conplaces and plumbing stores but smallestIcould get was 5mm

Alsowhat servo do you guys recommend??I'vegot a brand new 3kg hitec standard one here laying around but not sure if it will do the trick.

SEB!! ill have toorganiseanother time to meet up mate