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Author Topic: What electrics?  (Read 8831 times)

dhb141

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What electrics?
« on: December 08, 2011, 07:53:13 AM »

Hi,

Iíve just got myself a Seaport tug and inspired by the amazing rebuilds Iíve seen on the forum, I want to have a go myself but keep the costs as low as possible   My question is about the electrics.   I have an old 2 ch Sanwa Saber outfit which includes, servo, receiver, battery pack etc and Iím wondering if the batteries will give a reasonable running time -  itís a 6v nicad BEC pack - or do I really need to get something else?   The receiver says power supply 4.8 v to 8.4 v so Iím assuming that the original batteries with the boat is too much.    Another thought -  could I use the original batteries to power the motor and the Sanwa pack for the receiver?    Not being very well up on these things, any help would be gratefully received!   Thanks in anticipation.

Don
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Chameo

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Re: What electrics?
« Reply #1 on: December 08, 2011, 08:14:09 AM »

Hi Don,

your Sanwa Saber generally will do. You didn't mention anything about a speed controller which will certainly be needed. For the standard motor a little ESC for brushed rc car motors will be fine. But be careful: most of these ESC only allow 6-7 cell packs (7,2-8,4V) to be used. So I would also recommend a 6 or 7 cell racing pack with about 2000mAh. These ESCs mostly do have a BEC so that there is no need for a separate battery pack for your receiver.

Michael
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DickyD

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Re: What electrics?
« Reply #2 on: December 08, 2011, 08:31:10 AM »

Hi Don

When getting a speed controller make sure it has reverse, not all car controllers have this.

The tug is a boat, why not use a marine ESC.

You will notice that most people use a 6v 5amp or 6v 4amp SLA battery. These give you a long run time and also the ballast you will need to get your tug low enough in the water.

My build if helpful.  http://www.modelboatmayhem.co.uk/forum/index.php?topic=8411.0
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malcolmfrary

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Re: What electrics?
« Reply #3 on: December 08, 2011, 08:37:25 AM »

An old battery might be well into its retirement age by now, soa new one will be a good idea.
It is often cheaper to buy a "proper" ESC than a "bargain".  The "bargain" often ends up being dead money, as an almost immediate replacement, by a "proper" one is needed.
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Chameo

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Re: What electrics?
« Reply #4 on: December 08, 2011, 08:54:57 AM »

@DickyD
I like your build. I'm just converting my seaport tug to look like a Fairplay I/III/X tug.

Well, in fact I'ver never seen a brushed car controller without reverse during the last years but some marine controllers that don't have reverse. I'm using car ESCs in most of my boats without any problems.

I don't know if 6V are enough to get sufficent speed and pulling power.

By the way: Don likes to stay cheap so a dedicated marine controller and a SLA battery/charger might be too expensive.

Michael
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dhb141

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Re: What electrics?
« Reply #5 on: December 08, 2011, 09:12:37 AM »

Hi All,

Many thanks for the replies which are really helpful.  Sorry, I should have said that I intend to get Marine 15 ESC but was hoping that would have to be my only outlay.    Does anyone have any idea what length of run time I could expect from the 6v nicads, bearing in mind that being a tug, I want to be running it at something like scale speed?   And, will the 9v original battery pack not be suitable for the receiver I have?   It's not that I'm tight - I just don't like spending money!

Don
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Chameo

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Re: What electrics?
« Reply #6 on: December 08, 2011, 09:24:35 AM »

Hi Don,

doesn't your desired ESC have a BEC to power your receiver? If your receiver is rated up to 8,4 volts you shouldn't exceed this limit. Make sure that this voltage isn't forwarded to the servos because most servos are only rated up to 6V.

The length of the runtime can't be estimated without knowing the capacity of your battery.

Michael
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MikeA

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Re: What electrics?
« Reply #7 on: December 08, 2011, 09:24:47 AM »

when you install the marine 15 amp esc. it will take a small voltage from your main motor pack to run the receiver in the boat. what size batteries in the 6v nicad?
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john s 2

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Re: What electrics?
« Reply #8 on: December 08, 2011, 09:25:17 AM »

The marine 15 has a bec and is rated for 12v. Your high rated pack should be ok but if your motor was  6 v rated then may get a bit hot. But as long as you keep to scale speed all should be fine. Best try it and see. John.    
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dhb141

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Re: What electrics?
« Reply #9 on: December 08, 2011, 10:41:00 AM »

Thanks again to everyone for the replies.   I haven't actually bought the Marine 15 ESC yet so don't know anything about it - as I said, I'm a novice at these things!   Each of the 4 batteries in the Sanwa power pack is 1.2 v  700 mAh.  Will that give enough power to run the boat at low speed for say 1/2 hr or am I being too optimistic?   

Don
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MikeA

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Re: What electrics?
« Reply #10 on: December 08, 2011, 11:16:24 AM »

depending on how old the nicad is if its been sat for a while you will probably find its had it. unless it charges and holds the charge of course. the run time depends on the amp draw of the motor. in order to run for half an hour the motor will need to draw a very little 1.4 amps and that is unlikely. you will have to see but i doubt it. The voltage from the original boat battery pack will be too high also.

what motor are you using?
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dhb141

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Re: What electrics?
« Reply #11 on: December 08, 2011, 11:22:18 AM »

Hi Mike,

Thanks for your reply.   I've been using the nicads on and off for about 3 years now to power the steering on a yacht and they still seem to be holding their charge pretty well.   In the Seaport, I intended to use the original motor - at least for now.
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dhb141

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Re: What electrics?
« Reply #12 on: December 08, 2011, 11:24:23 AM »

Mike,

I forgot to say that if changing to a different motor would make a difference with the batteries I have, that would be an option for me - just don't want to have to spend any more than is necessary!
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Nige52

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Re: What electrics?
« Reply #13 on: December 08, 2011, 11:28:32 AM »

Thanks again to everyone for the replies.   I haven't actually bought the Marine 15 ESC yet so don't know anything about it - as I said, I'm a novice at these things!   Each of the 4 batteries in the Sanwa power pack is 1.2 v  700 mAh.  Will that give enough power to run the boat at low speed for say 1/2 hr or am I being too optimistic?   

Don

From what you say, you just have a receiver pack there? Is it a 4 cell pack of AA size batteries? If it is, that would only power a yacht for a short while, using the 2 servos. You will need a bigger pack to power a motor....preferably as Dickie says, a sealed lead acid battery of 6v...
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MikeA

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Re: What electrics?
« Reply #14 on: December 08, 2011, 11:33:21 AM »

if the boat has the standard motor and prop in it then i wouldnt advise on downsizing the motor as this would overload it and draw more amps lol.
heres a pic of a 6v SLA, the esc and the receiver:



the main battery drives the motor. The BEC or battery elimination circuit in the speed controller drives the receiver thus eliminating the need for a seperate battery pack to run the receiver. If you get the marine 15 esc it will hve a BEC in it. I personally use car esc's in my boats as their cheaper. at 20 quid a go for a marine esc you could buy a second hand car esc and nimh battery pack for the same price.
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dhb141

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Re: What electrics?
« Reply #15 on: December 08, 2011, 11:44:03 AM »

Very grateful for all the help and advise.   Nige, the battery pack I have with the Sanwa is a 4 cell AA size and I only use it on the yacht to power one servo for  the rudder - no sail control - which gives me as much sailing as I want in one go.

So from what you all say it looks as though I'm going to have to open my wallet and do some spending.   Those £1 notes are still legal tender, aren't they!?   :-).   Thanks again.
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MikeA

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Re: What electrics?
« Reply #16 on: December 08, 2011, 01:03:33 PM »

im a budget builder myself and try my best to do what i can on jelly beans. You will definatly need a new battery as those little 6v aa battery packs are only designed for the receiver, servos and other small load electricals.

i would personally use a car esc from ebay or something eg:

http://www.ebay.co.uk/itm/Mtroniks-20-Turn-Reversible-Car-ESC-Viper-/180771467071?pt=UK_ToysGames_RadioControlled_JN&hash=item2a16d1af3f

or this:
http://www.ebay.co.uk/itm/New-LRP-Ai-Car-Electronic-Speed-Control-/270868302836?pt=UK_ToysGames_RadioControlled_JN&hash=item3f11024bf4

tamiya one:
http://www.ebay.co.uk/itm/Tamiya-teu-101bk-speed-controller-brand-new-packet-/270867181805?pt=UK_ToysGames_RadioControlled_JN&hash=item3f10f130ed

if your willing to gamble and fancy some possible repair work this guy has all sorts of rc gear for sale:

http://www.ebay.co.uk/sch/i.html?_nkw=esc&_sacat=0&_dmpt=UK_ToysGames_RadioControlled_JN&_ssn=advan_gooch&_odkw=&_osacat=0&_trksid=p3286.c0.m270.l1313

if you bid dont bother going over ten pound including pnp for eg 7.50 bid pnp 2.50 etc.

you will also need a battery, nimh batteries can be found for nothing people practically give them away now. Dont bother with nicad there old news. if you go to wants and swaps or sales on this forum you might even be able to pick you a nimh battery for postage only. heres one on ebay:
http://www.ebay.co.uk/itm/GP-7-2v-3000Mah-NiMh-Battery-Pack-TC203-/320807209892?pt=UK_ToysGames_RadioControlled_JN&hash=item4ab1998ba4

that will work with the esc's, and the charger you have with the boat will charge it as long as the voltage of the charger is higher than the voltage of the battery.

for can get both parts for 20 quid.
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essex2visuvesi

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Re: What electrics?
« Reply #17 on: December 08, 2011, 01:09:32 PM »


tamiya one:
http://www.ebay.co.uk/itm/Tamiya-teu-101bk-speed-controller-brand-new-packet-/270867181805?pt=UK_ToysGames_RadioControlled_JN&hash=item3f10f130ed



Be wary of these ESCs in boats they are very sensitive to damp.  For the same money there are more suitable escs available
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MikeA

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Re: What electrics?
« Reply #18 on: December 08, 2011, 01:27:05 PM »

of course these a car esc's and not marine ones. The difference is that although they are electrically the same, more waterproofing goes into marine ones and they have a higher tolerance for running high amps for long periods. Its normal waterproof to your radio gear anyway, car esc's rely on air flow cooling the heat sinks on top them. As long as you dont go daft like trying to run a 700 motor on them overheating is not as issue, especially with the small motor your using. so it wont hurt putting the esc is a balloon or something similar.
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Netleyned

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Re: What electrics?
« Reply #19 on: December 08, 2011, 03:22:44 PM »

Run a 6vSLA and get enough runtime to numb the brain.
I used above batt with an £8 Blue ESC  O0 O0 and Grandson gets fed up after two hours.
BTW the SLA is 4.5AH and aforesaid Grandson runs it flat out most of the time (They do don't they  <*<)

Ned
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MikeA

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Re: What electrics?
« Reply #20 on: December 08, 2011, 04:12:00 PM »

if you not keen on bidding then you could buy these if your willing to wait for the post:
marine 1
http://www.ebay.co.uk/itm/130554115725?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648

or car 1
http://www.ebay.co.uk/itm/380387245289?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648

there hit and miss these esc's though, theres no QC on these chinese products so theres no guarantees they will work. its case of luck being on your side.

sla battery;

http://www.ebay.co.uk/itm/6V-4-5AH-RECHARGEABLE-SEALED-LEAD-ACID-BATTERY-SLA-NEW-/320698373781?pt=UK_ConsumerElectronics_Batteries_SM&hash=item4aab1cd695
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Netleyned

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Re: What electrics?
« Reply #21 on: December 08, 2011, 04:29:05 PM »

That's the blue marine one Mike
I know Dave No6 and others have had probs with them
but mine has performed ok.
I don't endorse the product though as mine could make smoke at any time.
The Dickie is more likely to be wrecked by the youngsters so the cheaper the better  :-))

Ned
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MikeA

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Re: What electrics?
« Reply #22 on: December 08, 2011, 04:59:51 PM »

i knew what you meant when you mentioned it. ive considered them myself. obviously ned your one of the lucky ones :-))
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dhb141

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Re: What electrics?
« Reply #23 on: December 08, 2011, 08:25:21 PM »

Thanks again to everyone who's taken the trouble to answer my questions - and especially to Mike for the links to various items I might want to get.   I'll do a bit of thinking, re-read all the threads again and then make up my mind which stuff to get.   Who knows, I might even post a few pics of the rebuild if I can pluck up the courage :-)
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MikeA

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Re: What electrics?
« Reply #24 on: December 08, 2011, 08:34:57 PM »

yeah some pics of your progress would be great :-))
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