Topic: Ahoy there!! (Read 7027 times)

Yamaha1 · « **on:** December 16, 2011, 04:38:16 pm »

Name is Mike - own in Somerset.

I'm retired, and just getting into boats, after some years of being an aeromodeler - but that was probably 30 years ago!!

I have bought the plans for a 36" Vosper ASRL ( made of ply ) which I am planning to power with a Torpedo 850 motor -
and a single shaft, driving maybe a 50mm 2 blade prop.

Not sure about an ESC yet - nor what type of batteries to use - as this will be my first foray into electric power!!

Does what I have listed so far seem sound - there is nobody near me to ask advice from?

There is such a confusing array of stuff from China listed that to say I'm confused by the choices is an understatement!!

The Torpedo 850 motor is rated as maximum about 13A at 6 - 12 volts. Is the cost advantage of Li-Po (11.1v 5000mAh maybe) direct from China the way to go -
if so, a Chinese ESC also, or are these, batteries and ESC's to be avoided like the plague from that source?

If someone experienced could kindly point me in the right direction, before I start wasting my money buying the wrong gear, I would be very grateful.

I already have the radio gear - I went for the 9 channel Eurgle 2.4ghz gear - so also need servos suitable for marine operation - recommendations?

Sorry to raise SO many questions on my first post - but it's a steep learning curve for this old codger!! Any recommendations are welcome - PLEASE!!!!!

Mike

Tug-Kenny RIP · « **Reply #1 on:** December 16, 2011, 05:00:06 pm »

Welcome to Mayhem Mike. Have a look around. Put your feet up and read, read, read. There's 290 thousand posts to get through.

You are welcome to put your location into your profile. (see Martin's green message at the top of the page) This might encourage local friends to get in touch with you.

If you'd like to post pictures of your build then we would be only to happy to help you in your quest.

Cheers

ken

john s 2 · « **Reply #2 on:** December 16, 2011, 09:11:32 pm »

Hello Mike. There are many threads on motors While the 850 is not a bad motor, ive got some. I think you would be better off with the 900 motor as sold by Action. This i have found to be better in all ways. With a boat your size it will push it nicely. John.

irishcarguy · « **Reply #3 on:** December 17, 2011, 08:38:34 am »

Mike welcome aboard, I see you are from Summerset, I live in Canada now but spent many happy days at RAF Locking & Weston Supermare. You will get lots of help here, you picked the right forum. Apart from motors ACTion also do electronics & they have great service too. There is also Westbourne & Cornwall Model Boats for all sorts of boat stuff. The guys on here know their stuff, take your time, mistakes can be expensive. Mick B.

dodgy geezer · « **Reply #4 on:** December 17, 2011, 10:58:24 am »

When you look at the cheap Chinese kit you are looking at quite a different set of items to the high-quality items you see elsewhere. Don't consider them as alternatives, consider them as complementary. Decide what your requirements are and purchase accordingly.

If you go to somewhere like Action Electronics you will get quality design, reliable components, advice and back-up support if anything goes wrong. But this will cost more money.

Cheap Chinese kit will be designed to do the job it is intended for, but is often built very cheaply, with minimal quality control. Poor quality components may find their way into the item, and soldering can be poor. When the items work they are remarkable value - if they do not you will get little support from a far-away factory in China where nobody speaks English, or from an ebay shipper...

In some cases this may not be an issue - if you are buying servos for less than £2 you can throw any that do not work away! I buy a lot from Giant God (who are based in this country) and find that they provide a very good service for the simple boats and planes I run. But if I were doing offshore racing, or flying a jet turbine, or simply wanting a known reliable operating envelope I would be using better quality kit....

The cheap kit is generally good so long as it is used within its limits (but there is a very cheap ESC around, usually identified as being in a black plastic box with blue anodised aluminium fins poking out, which is advertised as 110 amps and tends to fail at about 10amps). My advice would be to buy from a proven long-term seller in all cases, because they want to stay in business, so it's not worth their while selling complete rubbish. Expect high quality from people like Action, lower your expectations somewhat when buying cheap Chinese from Giant Cod and I don't think you will be disappointed....

Yamaha1 · « **Reply #5 on:** December 25, 2011, 10:57:49 am »

Sorry for the delay in replying, guys - been rather involved in trying to find the correct receiver connections for my brand new Eurgle (FlySky) 2.4 g system.

I couldn't believe that the instruction manual made NO reference whatsoever about connection polarity on the battery and servo pins!!

I have since ( thanks to Mayhem ) found out what I needed - and it works sweet now!!

I haven't started to cut any wood yet for my Vosper ASRL project, but have been slowly buying motors, shafts, rudders, etc for it - but still can't decide about the important bits like servos, ESC, and most importantly, what type of power source to go with!!

I would like several hours running time when it's finished - but can't decide whether the extra weight of SLA batteries is a better bet than a LiPo pack, as I have no experience of the latter.

In the meantime, I strayed onto eBay (fatal), and fell in love with a fully completed Perkasa launch, so I'm fairly sure it will soon reside with me!!

This may be a good plan, as I will be able to spend more time on the Vosper build, rather than rushing to get it finished, and maybe regretting my haste later!!

Will keep you posted!! Thanks very much for the replies so far - all info is very useful to this beginner.

Mike

pompebled · « **Reply #6 on:** December 25, 2011, 01:02:29 pm »

Hi Mike,

I'd like to add another motor option: a fan motor from the scrap yard.
It's the motor that turns the fan in front of the radiator.
Mine didn't cost anything.

These motors have a lot of torque and run on 12-24V without extra cooling (depending on propsize and runtime ofcourse).
As you mentioned wanting to have several hours of runtime, these motore are more efficient than the 850 and 900 motors, which as a rule of thumb convert about 25 - 30% of your battery power into heat (hence the need for cooling if you turn a big prop for prolonged runs).
I'm using such a motor for my 110 cm M.A.S. build: http://www.modelboatmayhem.co.uk/forum/index.php?topic=34033.0
Here's a side view:

I added cancooling and brushtab cooling as an experiment, most likely it's overkill, as tanktesting for 20 minutes full throttle showed only slight warming of the armature.
The cooling slots were filed into the housing, to let the heat out more easily, as these motors are completely closed, when mounted in a car.

If your 36" hull has to get on the plane, keeping the weight down is important, combined with your wish for long runtimes, an SLA battery isn't the way to go.

I'm going to run my motor on two 6S 5000mAh 25C Lipo packs, with a 50X prop the runtime will be over an hour at full throttle.
As I'm not going to run full throttle until the batteries are depleted, the 'several hours' should be no problem.

The picture shows the test set-up I used for tank testing, the smallest prop on the right is the X50, pulling 7A at full throttle, the black one on the left is a X75, pulling over 20A at full throttle.

The ESC in the left corner is a kit from a German company:

If you're into soldering your own ESC's this is the cheapest option available.
If you're not, I'd get one at ACtion.

Not quite the same size, shape and speed, my 60 cm tug, powered by a 5 pole 540 size motor, runs for five hours full throttle on two 2S 4000mAh Lipos(7,4V), wired in parallel.

Regards, Jan.

Yamaha1 · « **Reply #7 on:** December 25, 2011, 10:56:46 pm »

Thanks for that, Jan - very interesting article - and that motor looks ace. Maybe a bit big for my project, but certainly worth considering in the future, as I also love experimenting with different projects - my shed is littered with half-compleated "brainwaves" !!

As for the ESC - yes, I would be interested in making from a kit - do you have more details of the supplier, please?

As for the batteries, your comments on SLA's are noted - I think that LiPo seems to be my best option.

Mike

dodgy geezer · « **Reply #8 on:** December 26, 2011, 11:09:34 am »

Quote from: Yamaha1 on December 25, 2011, 10:56:46 pm

....As for the batteries, your comments on SLA's are noted - I think that LiPo seems to be my best option.

Mike

You suggest that you have not got a lot of experience with batteries - pardon me if I am teaching grandmothers, but it's probably worth mentioning a few points about the difference between LiPos and 'normal' batteries.

Batteries like SLAs are pretty tolerant about how they are used. You charge them up with a pretty standard charger, run them till the motor goes slow, and then charge them up again. Straightforward.

LiPos are a bit special. Each cell gives around 4.2v, and they commonly come in packs of 2 or 3 cells, giving 8 or12v. The cells are very light, and more delicate than SLAs - they can be damaged by being dented.

The voltage of a Li-poly cell varies from about 2.7 V (discharged) to about 4.23 V (fully charged), and Li-poly cells have to be protected from overcharge by limiting the applied voltage to no more than 4.235 V per cell used in a series combination. Overcharging a Li-poly battery can cause an explosion or fire. During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V, otherwise the cell may be damaged. This means that you need a special charger (called a balanced charger) to charge your cells, and it helps to have a special circuit on board your boat to tell you when the 3v discharge limit is being reached - otherwise you need to time your battery use quite carefully....

Brushless motors are often used with LiPos - these batteries can pump out the huge amounts of power that brushless motors can make use of - so brushless ESCs are often provided with circuitry which cuts the motor power when the 3v limit is reached. Ok for planes, which can simply glide down - not so helpful for boats....

pompebled · « **Reply #9 on:** December 26, 2011, 01:24:24 pm »

Hi Mike,

The manufacturer of the kits is here:
http://modellbau-regler.de/xtcommerce/index.php?cat=c4_Regler-Bausaetze.html&XTCsid=8g9cpa3gftde8nj0vaqbjouh86
They have a number of kits, depending on your needs.

The kit I purchased is this Type 1, as I plan to use more than 12V:
http://modellbau-regler.de/xtcommerce/product_info.php?info=p54_Bausatz--Volksregler--Typ-1-HV-Ohne-BEC.html&XTCsid=8g9cpa3gftde8nj0vaqbjouh86
This ESC has no BEC, so I'm using a seperate UBEC to supply the receiver (and the servo) with power:
http://www.ebay.nl/itm/ws/eBayISAPI.dll?ViewItem&item=290602779818&ssPageName=ADME:B:EOIBSA:NL:1123
This type is very common on eBay, I always try to find the lowest price.

If youre sticking with 12 SLA or 3S Lipo, this Type 2 has an on board BEC, so there's no need for an external UBEC:
http://modellbau-regler.de/xtcommerce/product_info.php?info=p61_Bausatz--Volksregler--Typ-2-Mit-1-Amp-BEC.html&XTCsid=8g9cpa3gftde8nj0vaqbjouh86

If youre going to use Lipo's, you'll need an external Lipo saver to avoid draining the batteries below 3,3V per cell, which will damage them, as Dodgy G has pointed out.

I prefer a liposaver like the Graupner 6495:
http://www.graupner.de/de/products/843d18cf-1eaa-4aa4-a3d0-fb05359d6f7f/6495/product.aspx
This device reduces the output, so you can get your boat back when the Voltage starts to drop.
Or you use something like this with a loud beeper and flashing Led:
http://www.ebay.de/itm/Lipo-Saver-Lipo-Alarm-Checker-3S-8S-Lipo-T-Rex-450-500-/150708895537?pt=RC_Modellbau&hash=item2316f33f31

Personally, I keep an eye on the speed of the model, when full speed isn't available anymore, I bring the boat in for a fresh battery pack.

If this all sounds like too much of a hassle, there are ESC's available with a build in liposaver also suitable for brushed motors like this one:
http://modellbau-regler.de/xtcommerce/product_info.php?info=p52_AS12-40RW-Evolution-II-EASY---Lipo.html&XTCsid=8g9cpa3gftde8nj0vaqbjouh86

Obviously these are already manufactured.

Regards, Jan.

Yamaha1 · « **Reply #10 on:** December 30, 2011, 05:42:10 pm »

Well guys, I certainly appreciate the useful advice.

Dodgy - you are correct - I have no experience of any other sources than SLA or NiCad!! Your advice was very helpful, and has been noted.

Seems I will have a stab at LiPo power - I have bought an Accucell 6 charger, so should be able to charge them safely.

I did get that built Perkasa that I mentioned - and that came with a 3750 NiMh battery - not sure how long this will run 3x 540 motors,

Still not sure whether to risk going with "direct from China" LiPo's - or splash out for more expensive UK sourced ones.

http://www.ebay.co.uk/itm/290602750561?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 caught my eye - what do you think?

Also these servos - http://www.ebay.co.uk/itm/290602756179?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 - any thoughts on these?

Pompebled - thanks for the links to the German company, and also your very helpful advice.

This Perkasa I just bought has come with several ACTion ESC's and mixer and power panel, etc - plus rotating guns and radar - but not sure they have all been wired
together in the best way - still trying to work my way through the wiring without a wiring diagram of how he configured everything to work together!!

One problem I have discovered is the steering - the rudder was going rh on a left stick - and lh on a right stick. Ah, thinks me - reverse that channel on the Eurgle tx -
that worked for the rudders - but the mixer is now slowing the wrong prop on a turn!!

Will contact Action after the hols - maybe he can advise.

Mike

dodgy geezer · « **Reply #11 on:** December 30, 2011, 08:19:48 pm »

Quote from: Yamaha1 on December 30, 2011, 05:42:10 pm

...
Still not sure whether to risk going with "direct from China" LiPo's - or splash out for more expensive UK sourced ones.

http://www.ebay.co.uk/itm/290602750561?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 caught my eye - what do you think?

Also these servos - http://www.ebay.co.uk/itm/290602756179?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 - any thoughts on these?
...

Lipos are a little non-intuitive for someone used to standard batteries, and need to be treated with respect - but they go fast!

Your servo spec seems high - 20Kg! I would have thought 2Kg was ok. And why 4 of them?

Note that buying from outside Europe attracts duty. As I recall, below £18 there is no charge. Above £18, you have to pay a duty charge (which will probably be small) and a collection fee (which can sometimes be massive). It is a bit random as to whether it is applied - I try to avoid buying things above £18, but others on the site have been happy...

Note that you are responsible for return postage in the event of any problems. I suspects that this means, in practice, that you will not be returning anything, so let us hope it is all ok.

You will wait a long time for this. Delivery times are in the order of 1 month - and you have to wait longer before complaining...

One way to get round these problems is to buy in Europe. I thing R2Hobbies has a warehouse in Germany, for instance. And Giant Cod is a UK shipper who goes over to HK, buys stuff up and then sells it over here, giving you UK service at a bit more than HK prices. I am a happy customer and can recommend them - they do servos and lipos:

http://www.giantcod.co.uk/servo-c-23.html?page=1&sort=2a&showAll=1&order=products_price%20ASC&max=50

http://www.giantcod.co.uk/cell-lipo-battery-c-1_114.html?max=50&order=products_price+ASC

Yamaha1 · « **Reply #12 on:** December 30, 2011, 08:39:51 pm »

"Your servo spec seems high - 20Kg! I would have thought 2Kg was ok. And why 4 of them?"

I wasn't thinking about the torque of them particularly - just thought they are metal geared, so must be better - and a very good price, I thought!

As for the quantity - my Eurgle 9 ch radio didn't come with ANY servos - so other than plundering an old Sanwa 35 meg set for those servos,
I do need to build up a stock of them!!

Will look more closely at Giant Cod, but I've always had quick service from China - sometimes 6 - 7 days - and no extra Import charges so far!!

The quest continues!! Keep the pointers coming, please.

Mike

dodgy geezer · « **Reply #13 on:** December 30, 2011, 09:19:56 pm »

Quote from: Yamaha1 on December 30, 2011, 08:39:51 pm

I wasn't thinking about the torque of them particularly - just thought they are metal geared, so must be better - and a very good price, I thought...

Yup - HK prices are always going to be good. Keep each order below £18 and the total price should stay good....

Looking at GC, you can get some 6kg ball bearing servos (plastic gearing, admittedly) for slightly cheaper - even including postage: http://www.giantcod.co.uk/sg5010-towerpro-servo-torque-p-205.html

Just be wary of the really cheap ESCs that sometimes occur on ebay....

john s 2 · « **Reply #14 on:** December 31, 2011, 10:48:01 pm »

Mike. You mention having a problem with the rudder turning the wrong way. By altering your servo hook up you can correct this. Im not good at explaining things , but if you have a servo with say an equal arm one side goes towards you the other away so change the side the link fits on to give you reverse action. This may involve moving the servo. John.

pompebled · « **Reply #15 on:** January 01, 2012, 11:16:22 am »

Hi Mike,

I'm running a couple of these metal gear servo's and they work fine.
Keep in mind that for those prices you'll come across the odd servo that will work for a week and stop without an appearant reason, QC is non existant at those prices.

DG had it almost right; it's HobbyKing that has a European warehouse in Hamburg, saving you shipping time an customs hassle at a slightly higher price.
http://www.hobbyking.com/hobbyking/store/index.rc
Check if the article has 'DE warehouse' in its description, then it's available from Hamburg, as an example:
http://www.hobbyking.com/hobbyking/store/__10913__Turnigy_5000mAh_4S_25C_Lipo_Pack_DE_Warehouse_.html

Regards, Jan.

Yamaha1 · « **Reply #16 on:** January 26, 2012, 01:25:00 am »

Hi guys - me again!!

Well, I sorted out the problem on the Perkasa, with the wrong prop stopping in a turn - servo reverse sorted the rudder - and swopping over the motor outputs from the ACTion P94 mixer sorted out the prop problem - although I discovered the starboard motor was fitted with a LH prop - but rotating clockwise on forward!!

Sorted this by just reversing the feed connections to that motor. Other than my bath, it has yet to be run - as it didn't sink in there, as soon as we have a decent day it will be put through its' paces.

I did get a couple of LiPo's from China - http://www.ebay.co.uk/itm/290602750561?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 - and they seem OK on the bench - will have to see if they actually perform like 5200 mAh endurance!!

Also got a 3S LiPo for my Eurgle transmitter - admittedly I wasn't sure if it would actually fit the battery compartment - but it slid straight in!! The only problem I did find was that fitting in its' 3 connectors was a bit tight - so I lengthened the compartment by cutting away a plastic stop, so the spare connectors now actually slide out of sight into the tx case. Sorted!!

I have also fallen in love with a steam-powered Borkum launch, with an SVS power plant - so that will soon be with me!! Just have to fit my radio and battery into it - luckily I have some spare receivers, also from China, for my Eurgle.

As for batteries, I went a bit mad in Lidl the other week, when they have their rechargeable NiMH packs on sale for £3.99 - that was 4x AA 2500mAh, or 4xAAA, or 2xD cells 4000mAh - so been busy soldering up some packs.

This hobby is sure getting expensive - I think I may have to sell on my once-steamed Markie Scenic Showmans engine, which has sat in my cabinet for the past 5 years!!!

Mike

john s 2 · « **Reply #17 on:** January 26, 2012, 05:59:25 pm »

Theres no problem with using LiPos for a transmitter, except that without a low voltage warning you may run them to far down. For a transmitter normal Ni Mh batterys of 2600 cap give me more time than i need.John.

Yamaha1 · « **Reply #18 on:** January 26, 2012, 09:27:24 pm »

There shouldn't be a problem with that, John, as the Eurgle has a voltage read-out on the screen. Thanks for the heads-up on that, though.

In case anyone else is interested, the LiPo I use in the transmitter is a Rhino 2620mAh tx pack.

Mike

pompebled · « **Reply #19 on:** January 28, 2012, 10:51:26 pm »

Hi Mike,

The Lipo in your link is rubbish for anything pulling over 20A, it'll puff and die...

If you plan on running them wired in parallel it might work.

I have three 4000mAh 2S from the same manufacturer and managed to puff one in the first run on a Speed 600 turning a 36K prop.
The remaining two now provide the power, wired in parallel, for my tugboat, which has a five pole 540 motor.

For a big heavy boat, you can't go much cheaper than the Zippy, or Turnigy lipo's, or it'll cost you (as I've experienced first hand).

If you want to stay with this seller, go for this one:
http://www.ebay.co.uk/itm/11-1v-4200mAh-30C-3S-Li-Po-LiPo-RC-Battery-11-1-AKKU-V-/300633028783?pt=Radio_Control_Parts_Accessories&hash=item45ff1ff8af

Regards, Jan.

Yamaha1 · « **Reply #20 on:** January 29, 2012, 12:46:08 am »

Hi Jan

Well, today was a nice day, so we bundled everything into the van, and tootled of to the pond with the Perkasa - with one of THOSE LiPo's fitted for the motors. Thanks for the info
on them - I was going to order a couple more - but will think again now.

The boat did go reasonably well - top speed was less than I thought it would be - but 10 mins saw the performance die off, even with half the time just poodling, so I brought it in to change the battery!! It was still showing almost 11v when I got home, so should still be OK - it took a charge OK, anyway!!

Next I tried the 3700mAh NiMH pack that came with the boat - that one lasted about 3 mins just poodling about - as did the next NiMH pack I had made up from 10 Lidl's 4000mAh D cells!!

I do have here a Turnigy Watt meter which I'm gonna put in the boat before its next outing, just to see what power IS being used.
I did have a brainwave for a switch to turn on power for the motors - I wired in a 30A car relay which I can control from the "gear" switch on the tx - works well - but I haven't measured the current that takes yet - minimal I thought, but I will check.

It is handy to put the boat in the "dock, switch off just the motors with one switch on the tx, and sit back for a coffee and fag!!

I did come away a little despondant with the short run times, I think I was expecting more like an hour per battery - misguided it seems!!
I was thinking on the drive home, maybe I would disconnect the centre motor to conserve some power, as my club don't really appreciate "fast" electric boats,
preferring steam or sail, so I don't really NEED the speed, such as it was - albeit briefly!!!

The tx and rx batteries held up very well, and don't really need a charge yet, so that side of things is a success - Lidl's AA 2500mAh ones.

Maybe those cheap Chinese motors supplied are to blame - but the way they are fitted in a plastic frame, and glued to the hull, it would require major surgery to remove them now,
with the deck on.

There was a little water in the hull when I finished - is this par for the course? The prop shafts are very short, so maybe the culprit.

Mike

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Author Topic: Ahoy there!! (Read 7027 times)

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