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[TCC]

Hi, just a quickie, what will a 385 draw if it's off a 6vt SLA and is turning a 1 inch, 3 bladed 'naval' propellor. [E Raedesock made them & the running gear. The blades haven't been tweaked]

I don't have an ameter so I have to ask what the runnng and stall amps are.

Then if I'm using 4 motors, 2 each side. Do I just double those figures so as to get a ESC to control 1 pair? (2 ESCs.. 1 each side)

I'm using 2 '8' bobs boards at the moment but I don't think they'll be a long term solution [deep grooves across the surface from the wipers and one board starts earlier than the other*, and stuff like that. What's saved my steering is I've wired them in fore and aft pairs, not port and starboard.

* I know I just need to tweak the wipers but it's (2 B boards) is not an elegant solution. The model cries out for a rudder-mixer thingmijig]

[stallspeed]

http://docs-europe.electrocomponents.com/webdocs/0032/0900766b800320ab.pdf
For six volts,divide the figures by two .
J.G.

[stallspeed]

To get the stall current match the re385 with one of these two and you will get the stall current.
There are three other mabuchi 385 motors but I am sure yours is here.
http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_385pasa

J.G.

[Shipmate60]

TCC,
What model are they fitted in?

Bob

[FullLeatherJacket]

What model are they fitted in?

.......and how big is it (actual size, not the scale)? The Bobs Boards sound as if they should be handed into the nearest police station. A ruddermotormixer thingamajig is not a problem. Try this link:

http://www.action-electronics.co.uk/pdfs/P94.pdf

The 10A "Lite" version should do the trick with four x 385s, but they really are 12v motors.

FLJ

[Ghost in the shell]

Tcc I run 2x double MFA 885 motors in my Yamato off a 6v gel cell battery, in a set up not too dissimilar to your own, and I find that the total draw low enough for a 15amp esc to handle. 

I measured the load just with a multi meter

battery: 6v Sealed Lead Acid 4.5Ah
ESC Viper 15x2
Motor - 2x paired MFA 385

one pair of motors at FULL POWER draws 1.19A thats a 2.4A load off the battery

propellers were 4 blade 25mm units off propshop

[Ghost in the shell]

stalled, I only stalled one motor on yamato and that pulled 1.74A

so thats 3.48 for the pair.

stall all 4, boy you'd have to be really wrapped to do that, and you're just shy of 7 amps

[TCC]

What model are they fitted in?

.......and how big is it (actual size, not the scale)? The Bobs Boards sound as if they should be handed into the nearest police station. A ruddermotormixer thingamajig is not a problem. Try this link:

http://www.action-electronics.co.uk/pdfs/P94.pdf

The 10A "Lite" version should do the trick with four x 385s, but they really are 12v motors.

FLJ

Hi lads, and thanks.

It's HMS lion and it's about 5 ft long.

The 385's are termed "RS 385 SH", they're not in the modern PDF linked to.

Yes, the twin ESC and mixer looks great but £70-odd? It's either I go without or the kids don't get any pocket money... ah well, I just hope they don't bear a grudge when they're bigger.  I've alreay raided their piggybanks for money for posh fittings! 

12v? can do!! I need a new SLA for it and a 12er is as good as a 6er. Does that double my amps, stalled and running? I'm still in the 'Lite' version of P94 though, aren't I? 7 amps per pair stalled? Now if it's a 10 max ESC, I should put in a fuse of 7< but <10? Right? Maybe a 8 or 9 amp fuse per ESC?


I'm just looking over their smoke units: I'd Need a LOT of smoke. Does their S3 unit do well? I'm wondering if it's doable to split one into 2 funnels And still get noticable smoke 'on the pond' as 2 units weren't in the 08 naval estimates. [naval joke for us grey funnel types.  ]

Why are the boards Boards 'criminal'? I'm doing what they advise, stuck on top of a servo with their sticky back, with the wipers applying slight pressure (is why one starts earlier than t'other... one needs a tweak downwards as they're wiping as lightly as I can get. There's nothing like a nice gently wipe. ]

[wombat]

Hi TCC

The P94 - compare the cost against 2 ESCs plus a mixer plus the wiring. I think the Lite version is cheaper.

Moving to a 12V battery will double the stall current with respect to a 6V battery - at a given speed on the water, the power should not be significantly different.

Bob's boards are a good old-fashioned solution, but will not give the same fine control as a decent ESC. They will also suffer from reliability problems and wear. Also they will not be as efficient as an ESC and on lower speeds will be more likely to stall as the motors will have less torque than when running with an ESC at the same speed.

Wom

[stallspeed]

The 385's are termed "RS 385 SH", they're not in the modern PDF linked to.

http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_385sh

Why are the boards Boards 'criminal'? I'm doing what they advise, stuck on top of a servo with their sticky back, with the wipers applying slight pressure (is why one starts earlier than t'other... one needs a tweak downwards as they're wiping as lightly as I can get. There's nothing like a nice gently wipe. ]

Four diodes per bobs board will kill the arcing that ruins the boards.Connect as in the P45 switcher where the purpose is to protect the breaking relay contacts.
A single 20 pence bridge rectifier containing four diodes in a single four-legged component does the same and is easier to connect:
 ~ to motor
+ to +
- to - .
Switch contact cleaner helps too.

J.G.

[Ghost in the shell]

TCC, Yamato is 52" long, so not that much smaller than your HMS Lion, and each of my MFA 385's pull less than 2 aps stalled, rather than fuse individual motors, fuse them in pairs on the outbound leg of the esc with a 3A fuse, however you're not likely to stall both motors together.

[TCC]

Hi TCC

The P94 - compare the cost against 2 ESCs plus a mixer plus the wiring. I think the Lite version is cheaper.
I know mate, I was having a bit of fun. It looks the right solution, seriously. The video of shipmate60s cruiser (jeez.. that's BIG. A Transit owner?]) was illuminating.

Moving to a 12V battery will double the stall current with respect to a 6V battery - at a given speed on the water, the power should not be significantly different.
My question is, if I go 12v, do I go for the 10 amp 'pair' or the 20s? The 20's have more flexibility in that they could power bigger motors if i ever make another model. BUT I do't want to loose that fine imperceptible turning (control) of the propellors.. you know, when they hardly turn.

If the 20's will still give that, well there's not much £ difference so I may as well get the most flexible. [I don't think I'll be building any other RC craft but you never know]

Bob's boards are a good old-fashioned solution, but will not give the same fine control as a decent ESC. They will also suffer from reliability problems and wear. Also they will not be as efficient as an ESC and on lower speeds will be more likely to stall as the motors will have less torque than when running with an ESC at the same speed.
Yes, the set-up was actually from another model, it was put in this as a get-me-by to get it on the water, then I lost interest before I finished building it and thus never got round to buying the control part of it.

As for control, I did watch the props and I could ge them doing the very slow turns, bout... what... 20 RPM? But I take your points fully. I know they aren't the elegant solution I want.

I see that the 385s are a very gentle motor wheer amps are concerned.
Wom

Are you the lad who build them Wom?

[Shipmate60]

Just to remind you on a 10 1/2 foot Cruiser hull.

http://s282.photobucket.com/albums/kk251/shipmate600/?action=view&current=Picture030.flv

Bob

[TCC]

The 385's are termed "RS 385 SH", they're not in the modern PDF linked to.

http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_385sh

Sorry mate if I missed it.
Why are the boards Boards 'criminal'? I'm doing what they advise, stuck on top of a servo with their sticky back, with the wipers applying slight pressure (is why one starts earlier than t'other... one needs a tweak downwards as they're wiping as lightly as I can get. There's nothing like a nice gently wipe. ]

Four diodes per bobs board will kill the arcing that ruins the boards.Connect as in the P45 switcher where the purpose is to protect the breaking relay contacts.
A single 20 pence bridge rectifier containing four diodes in a single four-legged component does the same and is easier to connect:
 ~ to motor
+ to +
- to - .
Switch contact cleaner helps too.

J.G.

Hi Mate, it's not arcing, its wear. It's not that bad for now but it's starting to rut so you know whats going to happen with more and more use.

But I'll look in to protecting these boards while I'm using them, have you got a drawing or photo of this mod? I can't seem to find the p45 switchers.

Cheers

[TCC]

Just to remind you on a 10 1/2 foot Cruiser hull.

http://s282.photobucket.com/albums/kk251/shipmate600/?action=view&current=Picture030.flv

Bob

Hey Bob, that's not a model, that's a canoe painted grey. Have you do a write-up thread on the build? How are you moving it around? I don't know about you but I went as big as I thought practical (it has to go through doorways and up stairs) so that's why I ended up with the unfashionable scale of 1:144 whom no-one makes fittigs for :-( Even at about 5 ft, I still break things every time I move it. The ensign staffs have been bent and straightened moretimes than I can remember.. so you can guess my admiration for soeone who builds bigger than me. 

[Shipmate60]

I didnt actually build it. It was a hull made 26 yrs ago.
The builder passed away and the bits were stored in a garage for over 10 yrs.
I am slowly completing her after a complete hull refurbishment.
She just fits in the back of my Vectra Estate right up to windscreen, but when completed so stop any damage she will have to go on roof or trailor.

Bob

[TCC]

TCC, Yamato is 52" long, so not that much smaller than your HMS Lion, and each of my MFA 385's pull less than 2 aps stalled, rather than fuse individual motors, fuse them in pairs on the outbound leg of the esc with a 3A fuse, however you're not likely to stall both motors together.

Hi Mate
yes, I'll do that but I think I'll be going 12v so will that mean a new fuse rating? In a day of 2, I'll come back and re-read this when I'm more inclined and I'll probably see my errors and have someting sensible to say. Y'see, I have never fused anything so I dn't even know what type of fuses to go for, the car type or the round glass tubes with metal cap versions?

Is that a scratch built Yamato? What scale?

Cheers.

[TCC]

I didnt actually build it. It was a hull made 26 yrs ago.
The builder passed away
Ah that's a shame.

and the bits were stored in a garage for over 10 yrs.
I am slowly completing her after a complete hull refurbishment.
She just fits in the back of my Vectra Estate right up to windscreen, but when completed so stop any damage she will have to go on roof or trailor.

Bob

Ah, I see. I just have this mental image of you slamming on at a pedestrain crossing and skewwering the crossees with a set of anchors attached to a hull and deck! 

Nah seriously, whatever way you transport it, is going to need to be well built as the box for will act like a sail. Still, they need to be built big, mine looks as big as an Airfix kit when on the water. I now wish I'd gone 1:128 and just that bit bigger. Alas...

Anyway, cheers mate

[FullLeatherJacket]

But I'll look in to protecting these boards while I'm using them, have you got a drawing or photo of this mod? I can't seem to find the p45 switchers.

P45?? Nah - the boy has a revenue obsession. It's P44, and it's here.........

http://www.action-electronics.co.uk/pdfs/Limit%20Switches.pdf

.......and it works a treat, Sandy/Barry/Gonzales/Microgyros/Stallspeed/Whatever your name is this week.

FLJ

[stallspeed]

Pepé Le Pew?

[Pepé Le Pew]

TCC,I'm pretty sure track wear is down to arcing even if you can't see it.
A method for shaping female portions in a casting die employs a copper coated male plug.The submerged arc gradually cuts away the metal in the die.

The best use for Bobs boards are coasters unless you have one of these massive boats that just goes nought to full speed whatever you do.

Regards
Pepé,Stablemate of Speedy Gonzales