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[Killerinc]

Hey Everyone, I'm very new to all this so please keep it simple..
I have a motor from a Robbe boat, a BRUSHED 7.2V Super 600 22k. I'm not too sure when it comes to Brushed motors which battery to use in this as the Robbe Boat PDF manual states using a Sanyo 7 N C2,4 k AMP.
It's going in a 17" no name small Boat. I think i should get a 2S, but not sure about the maH or the C Rating. There is no ESC just an old analog speed controller with a servo controlling it, so I'm not sure what type of Amps this could handle. a hobby shop told me 25amp is the max. I was thinking a Turnigy 1400maH 2S 15C .
Also is there a BEC that will work for a Brushed setup for a Futaba radio, if so please include links. I was also thinking of getting an ESC but there hard to find one for Brushed boats above 30Amps and work with Li-po, any suggestions of one i would appreciate the link for it.

Thanks for the help ahead of time

[AlisterL]

I can help some of the way here.

Firstly, the type of battery doesn't matter to the speed controller or the motor - it's all volts and amps when it gets that far.
The Sanyo is, at an educated guess, 7.2 volt, 4000 mAh (milliAmps per hour) based on the info you provide. Therefore the closest Li-Po you could get would be a 2 cell (2S) 4000 mAh - this would give you 7.4 volts nominal.
In terms of current draw, the limiting factors are what the motor will draw, what the ESC/Speed Controller can handle and what current (Amps) the battery will supply. Li-Po's will supply a LOT of current in a very short time frame - that Turnigy you mention, rated for 15C will supply 1400 mAh for one hour - or can supply 15C times 1400 mAh in a burst. That is way more than anything scale (probably even fast electric types) would need. If the hobby shop says the speed controller will handle up to 25 Amps then a 20 Amp fuse either side of the controller would protect the controller you have. Electronic Speed Controllers can be sourced that handle more than 25 Amps. Action Electronics I believe, and Mtroniks, have ESC's to handle this. Electronize may have - I'm not sure about those. See the Traders pages for links for these, or just Google...
As for BEC's - some will recommend for and others against. Mtroniks ESC's have a BEC built in. I don't think that the Action ESC's do - someone (probably several!) people will correct me if I'm wrong. No idea about Electronize. You can buy and install these separately from the ESC/SC anyway. And I would recommend a Li-Po guard to protect against over-discharge of the Li-Po too. I imagine that E-Bay or your local equivalent will have these, if not your local hobby shop. Presumably if you are thinking about Li-Po you will know you need (or already have) a suitable charger.

Any other advise will need some detail about the boat you are putting the motor/ESC/battery combo into and others more knowledgeable than I will likely assist. Details of the prop will be a requirement - this affects the current draw (amps) of the motor, as will the type of hull displacement or planing - photos work well :)

HTH!

[CF-FZG]

The battery you describe is a Sanyo 7 cell Nixx Sub-C pack rated at 2400mAh (2.4Ah)

As Alister says, it should run okay on a 2S LiPo pack of similar capacity


Mark

[wibplus]

Hobbyking in the far east do a step-down voltage regulator which will handle input voltages up to 23v and output 5v at 3 amps. This is essentially a BEC and costs a few pennies. This will run your receiver at a safe voltage.  

Hope this helps.  

[AlisterL]

Foiled by the , = . convention... Thanks Mark :)

[wibplus]

Foiled by the , = . convention... Thanks Mark :)

Eh ????   

[CF-FZG]

Eh ????   

It was just the way the OP wrote the battery details from the manual - European convention writes a ',' to represent a decimal point and vicky-verky with a 'thousands' definer.


Mark

[Killerinc]

Thx CF, but the boat that this came out of does not have the same ESC so the 2400 capacity will be overboard for my speed controller from what i learned i think and size of the 2400 battery wont fit either. What i was told to figure out Amps is 15C x 2.4ah=36amps, so cant do that. I figure now that i know this i can do Max 1400mah 15C. I am looking into getting a real speed controller but cant find one over 30amps so far.

Thx Alister, for the fuse tip, good idea. I will check out those places for a real ESC. I have on order from ebay a low voltage buzzer.
As for the prop, i have no idea and will take a few shots, but i do know is i ran it with a 9.2v Nimh, and both Motor and speed controller ran cool, i do have some coils around the motor for water cooling. I was told that if the prop is too big or pitch it will get too hot and need to go smaller.

[philk]

What i was told to figure out Amps is 15C x 2.4ah=36amps,

sorry you've lost me with this one what are you trying to work out because that makes no sense at all


phil

[MikeA]

I dont think youl need a speed controller over 30 amps you know. i just looked up that motor and its operational current is 20 amps max is 25. bear in mind that if ya get the set up right i doubt itl be over 15.
a golf kart luggin to fat blokes down a fairway is probably about 60 amps   
somebody better check me on this

also killerinc not bein presumptuous I think you got the mah and amps mixed up. In simple terms the mah on a battery is like the capacity of a petrol tank. The higher the mah is the more juice it can supply, but the motor isnt slave to the battery though. The motor is the demanding participant , the more work its made to do the more amps it requests from the battery. And if you have a motor that sucks up a lot of juice (amps) then your gonna need a big tank (mah)

I have a speed 600 motor. it runs from a 8.4v 3000 mah battery. controlled by a 30 amp speed controller. i have a 25 amp fuze on it just to be safe. but i reckon i could put a 10 amp fuze in it and i dont think it would pop. But thats something ill do in the test tank.
 

[Killerinc]

What i was told to figure out Amps is 15C x 2.4ah=36amps,

sorry you've lost me with this one what are you trying to work out because that makes no sense at all


phil

Thats what someone on another forum told me how to figure out how many Amp ESC you need. Also to stay under the AMP rating for the motor.

[Timo2]

Hi Boys ( you all )

   Go to Sckool       try     http://batteryuniversity.com/learn/

 Timo2

     

[Killerinc]

I dont think youl need a speed controller over 30 amps you know. i just looked up that motor and its operational current is 20 amps max is 25. bear in mind that if ya get the set up right i doubt itl be over 15.
a golf kart luggin to fat blokes down a fairway is probably about 60 amps   
somebody better check me on this

also killerinc not bein presumptuous I think you got the mah and amps mixed up. In simple terms the mah on a battery is like the capacity of a petrol tank. The higher the mah is the more juice it can supply, but the motor isnt slave to the battery though. The motor is the demanding participant , the more work its made to do the more amps it requests from the battery. And if you have a motor that sucks up a lot of juice (amps) then your gonna need a big tank (mah)

I have a speed 600 motor. it runs from a 8.4v 3000 mah battery. controlled by a 30 amp speed controller. i have a 25 amp fuze on it just to be safe. but i reckon i could put a 10 amp fuze in it and i dont think it would pop. But thats something ill do in the test tank.
 

Ok thx mike, 30a ESC it is, i will start looking.
I understand batteries a lil better but i noticed the bigger the mah rating obviously the bigger in size the battery, so cant fit that much

[MikeA]

well mah really means two things it also means the amount of current the battery can discharge per hour. if you have a 1000mah battery or we could just say a 1Ah battery same thing. And we have a motor that wants to suck up 1 amp then the run time will be 1 hour. If the motor wants 2 amps then the battery will only last half an hour. if the motor wants 60 amps the battery will last 1 second!! 

do you have the transmitter, rceiver and the the rest of the stuff for it?

what is your set up as far the drive train is concerned?  are you using a reduction gearbox or direct drive ?

[MikeA]

i just had a read threw again and i was recommended this:
http://www.shopadilly.co.uk/Auctions/brushed+esc
this speed controller has the bec built in. and its compatible with both lipo and nimh.

if you look around ebay youl find a few suppliers of them different but similar price range.  The draw back is it has no reverse because its an aircraft speed controller. secondly aircraft transmitters have no centre return spring on the throttle so the speed controller registers 0 throttle as the leaver fully back. means youl have to remove the return spring in the transmitter.
there are instructions in the futaba hand book to do this but just grab a screw driver and have a look its very simple to do:



i hope you alo realise that if you are to use a lipo battery youl need a balance charger for it. Dont use a standard nicd/nimh charger itl put a hole in ya house!!

[Killerinc]

well mah really means two things it also means the amount of current the battery can discharge per hour. if you have a 1000mah battery or we could just say a 1Ah battery same thing. And we have a motor that wants to suck up 1 amp then the run time will be 1 hour. If the motor wants 2 amps then the battery will only last half an hour. if the motor wants 60 amps the battery will last 1 second!!  

do you have the transmitter, rceiver and the the rest of the stuff for it?

what is your set up as far the drive train is concerned?  are you using a reduction gearbox or direct drive ?

So then for my motor u said is 20a , 25 max, how do we know how much it would draw in the water under load? so then a 1.4ah would last how long. what is the calculation to figure that out?
I'm going to get a 30a ESC w/reverse and BEC which battery should i go with then if my calculations were wrong based on my setup?

[Killerinc]

i just had a read threw again and i was recommended this:
http://www.shopadilly.co.uk/Auctions/brushed+esc
this speed controller has the bec built in. and its compatible with both lipo and nimh.

if you look around ebay youl find a few suppliers of them different but similar price range.  The draw back is it has no reverse because its an aircraft speed controller. secondly aircraft transmitters have no centre return spring on the throttle so the speed controller registers 0 throttle as the leaver fully back. means youl have to remove the return spring in the transmitter.
there are instructions in the futaba hand book to do this but just grab a screw driver and have a look its very simple to do:



i hope you alo realise that if you are to use a lipo battery youl need a balance charger for it. Dont use a standard nicd/nimh charger itl put a hole in ya house!!

i would like to have reverse though but i will take a look.
I have a friend who has a really good charger and will use his until i get mine, but thx for the tip

[Killerinc]

I dont think youl need a speed controller over 30 amps you know. i just looked up that motor and its operational current is 20 amps max is 25. bear in mind that if ya get the set up right i doubt itl be over 15.
a golf kart luggin to fat blokes down a fairway is probably about 60 amps   
somebody better check me on this

also killerinc not bein presumptuous I think you got the mah and amps mixed up. In simple terms the mah on a battery is like the capacity of a petrol tank. The higher the mah is the more juice it can supply, but the motor isnt slave to the battery though. The motor is the demanding participant , the more work its made to do the more amps it requests from the battery. And if you have a motor that sucks up a lot of juice (amps) then your gonna need a big tank (mah)

I have a speed 600 motor. it runs from a 8.4v 3000 mah battery. controlled by a 30 amp speed controller. i have a 25 amp fuze on it just to be safe. but i reckon i could put a 10 amp fuze in it and i dont think it would pop. But thats something ill do in the test tank.
 

With your Super 600, how long does the 3000mah last on your boat?

[MikeA]

to be honest with ya i havent got it to run properly yet i took it for its maiden run. it lost signal after 15 ft got caught in the wind and stuck in a tree growing out the bank. i had to strip down and go wading up to me neck in nout but me boxers. i got it back but i had to go home commando i am currently running a 27mhz futaba kit but thats all going as hopefully tomorow ill get my new 2.4ghz in the post. I dont have no suppression caps on my motor either all added up problems. I would personally reccomend getting a 2.4ghz radio kit. im getting an fs gt2 which is cheap but got good reviews. If i manged to get the boat to work yet id tell ya but i did some calculations and i reckon it will be roughly 18 minutes. well see though. I have 2 batteries so ill swap em over when ones flat.

as far as amp draw on your motor all i can say is do a test. get the motor and the power train in. hook it up to a battery.

look at post 27 about halfway down to see how a test can be done
http://www.modelboatmayhem.co.uk/forum/index.php?topic=31199.msg308421#msg308421

to work out what battery you need do

expected run time X amp draw /60 = battery mah required

to work out how long your a 1.4 will last do

1.4 X 60 / amp draw = mins

these are rough calculations but give you an idea

[Killerinc]

Wow, sounds like a lil bad luck there, but it could have been worse javascript:void(0);
Ok i have those 3 caps on my motor i just checked, and it sounds like i have the same 27mhz Futaba, lol
I bought the FS GT2 for my other boat and i love it and will most likely upgrade soon for this boat, but for now it will have to do. Hey if i just get another FS GT2 RX can i use the TX for 2 Boats?
That info about figuring out Amp draw is very very helpful and will try that out tomm. Once i do that i just have to find the biggest battery that can fir in that small compartment.
Oh today i purchased a Proboat PRB2314 40amp ESC w/Reverse and BEC for $33US.
Let me know how your upgrade goes

Mike and All u guys been great and so helpful, i really appreciate it.

[MikeA]

with the fsgt2 you can just buy another rx you dont need another tx. you just pair it with the transmitter again. Obviously your not a complete noob. When i get my fs gt2 im gonna have to modyfy the trigger to use with my speed controller. if i had a reverse i wouldnt need to but ohwell till then. keep us posted on your tests dont forget to use fuses.

[Killerinc]

Oh ok, if i bring both out to the lake at the same time do i have to pair them every time i use it, or just once on both?
I'm new to boats, about 22yrs ago i had a electric Grasshoppers and a Falcon, and a Formula One race Car, so i know a thing or two. Been gone for a while, So many new things, lol
Oh and I wont forget the fuse.

[MikeA]

well you the pair the boat you want to use with the transmitter. this youtube video shows you how to pair the fs gt2:
http://www.youtube.com/watch?v=3WiSJYhmNv0&feature=relmfu

I got mine today and i love it i had to modify the trigger throttle so its resting point is full reverse. on my esc thats neutral.

[Killerinc]

Yeah but lets say if first one is already paired, if i get a second one and pair it, when i want to use the first...do i have to pair the first one again and so on every time i switch boats?

Nice, you'll like it, i like mine and has great range and response for a $19 RX and TX.

[MikeA]

yeah everytime you want to change boats youl have to pair it again. Only takes a second though.