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Author Topic: ESC Suggestions  (Read 400 times)

Seacommander

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ESC Suggestions
« on: October 11, 2020, 08:29:10 PM »

Hello
I picked an old MFA spearfish up, cheap, in lovely condition with a Torpedo 850
I have 12v Gel batteries already and it's running a 50mm Prop
Any suggestion on a good speed controller for this set up
it's a put it in the car at a min's notice type boat and a bit of fun
Thanks
Mark
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Stan

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Re: ESC Suggestions
« Reply #1 on: October 11, 2020, 08:40:11 PM »

Hi seacommander see the link to the MFA web site.  This motors stall current at 12 volts is 61. 34 amps so you are going to need something that can handle this or a little bit more


https://www.mfacomodrills.com/pdfs/RE850.pdf
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Des

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Re: ESC Suggestions
« Reply #2 on: October 11, 2020, 09:01:15 PM »

Hi Seacommander

I disagree with the previous reply.

Using the link provided to the MFA data sheet, we find that the full load current for this motor is a little less than 11 Amps.  If you install a 15A fuse between the ESC and the motor, then this will blow long before the ESC self-destructs in the event that your prop(s) get fouled and jammed.  So an ESC with a continuous current rating in excess of 15 A will be adequate, and will cost much less than one rated in excess of 60 Amps.

Also, don't forget that you are usually not likely to run the boat flat out;  dialling back your throttle settings on your Tx will reduce the amount of current actually drawn by the motor quite significantly - for instance, running the motor at 90% of its full load rating will reduce its current draw by almost 30%.

Des.
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Stan

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Re: ESC Suggestions
« Reply #3 on: October 11, 2020, 10:10:16 PM »

Hi Des thank for your reply yes it shows a low current draw.And you could use  15 amp controller and fuse. In the uk at at the moment you can buy a decent 60 amp controller for under £18. Yes the stall current may never happen but for very little expense you can have controller that can coupe with this. But you pays you money and makes you choice.




Stan.
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Seacommander

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Re: ESC Suggestions
« Reply #4 on: October 11, 2020, 10:37:13 PM »


Thanks for points made,
can anyone suggest a particular speed control  make / model from experience with a similar set up
Thanks
Mark
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Stan

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Re: ESC Suggestions
« Reply #5 on: October 11, 2020, 10:48:23 PM »

Hi if following the advice on a 15 amp controller I would use a 20 amp with 15 amp fuse.Mtronicks viper at 20 amps..




Stan
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Stan

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Re: ESC Suggestions
« Reply #7 on: October 11, 2020, 11:25:59 PM »

Hi Tarnis the spec for this only allows up 10.6volts the drive battery will be 12 volts.




Stan.
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Des

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Re: ESC Suggestions
« Reply #8 on: October 12, 2020, 12:24:40 AM »

Check out the Action Electronics section on the Component Shop website - there should be something there.
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Taranis

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Re: ESC Suggestions
« Reply #9 on: October 12, 2020, 07:34:59 AM »

Well spotted Stn  :-)

derekwarner

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Re: ESC Suggestions
« Reply #10 on: October 12, 2020, 08:02:31 AM »

 %)  does the specification not indicate 10.8v to 11.1v?...........[I go to :-) ]
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Taranis

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Re: ESC Suggestions
« Reply #11 on: October 12, 2020, 08:25:26 AM »

A fully charged 3S is 12.6, 4.2 volts per cell end of charge. A 12 volt pb will be higher at end of charge


 11.1 is I expect nominal voltage. 


I should not have taken the spec for granted and didn't read the OP requirement  :embarrassed:  my bad

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Re: ESC Suggestions
« Reply #12 on: October 12, 2020, 08:30:40 AM »

 
Hi if following the advice on a 15 amp controller I would use a 20 amp with 15 amp fuse.Mtronicks viper at 20 amps..
Stan


Most of the Mtronik's unit can be setup for  Lead-acid batteries....

https://www.mtroniks.net/cat/Boat-Speed-Controls#category_id-583/applied_filters-f11%7Cf5%7Cf6/order-PLH/page_number-1/items_per_page-240

https://www.mtroniks.net/prod/Boat-Speed-Controls/Viper-Marine-20.htm
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malcolmfrary

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Re: ESC Suggestions
« Reply #13 on: October 12, 2020, 10:50:42 AM »

When the Spearfish came out, gel cells were sort of the state of the art, and had to be tolerated.  A 3S Lipo of the same capacity will result in a much livelier boat due to the huge weight saving.  Also a lot easier to carry, and probably better run time.
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Stan

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Re: ESC Suggestions
« Reply #14 on: October 12, 2020, 01:30:43 PM »

 
 Having spoken to MFA this morning the figure of 10.82 amps of the 850 motor at maximum efficiency is with no load applied to the motor. When the kit was made M F A  fitted a 30 amp speed controller and a 12 volt 7amp gel cell battery. So using the information supplied from M F A you need a E S C that will handle 30 amps  fit a in line fuse should you decide not to do that  and your motors stalls then it will pull 61 amps plus which will result in very poorly E S C. I have taken the time to consult with the supplier of this model and i would like to thank them on your behalf .

Please note i would like to clarify the information on the E SC and battery were supplied by M F A como I hope this helps


Stan. :-)) :-)) :-)) :-)) :-)) :-))
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Colin Bishop

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Re: ESC Suggestions
« Reply #15 on: October 12, 2020, 03:06:25 PM »

That sounds like a very high discharge rate for a 7Ah Gel Cell. Most are not designed for high discharge currents. I found this table which gives an indication of rates for scooter batteries but they are proably designed for higher rates than the ones we commonly use in our boats.

https://electricscooterparts.com/battery-maximum-discharge-current-chart.html

Colin
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Stan

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Re: ESC Suggestions
« Reply #16 on: October 12, 2020, 04:20:47 PM »

Hi Colin MFA did say the motor may pull 15 to 18 amps but they fitted a 30 amp controller we assume has a safety measure. We could go on talking about this forever if I was the person who first asked the about this I would feel a little confused.
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Tug Fanatic

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Re: ESC Suggestions
« Reply #17 on: October 12, 2020, 08:14:09 PM »

That sounds a horribly high discharge for a 7A Gel Cell. I would expect the voltage drop to be bad and it won't do anything for the life of the battery either for a single charge and for the life of the battery.

I wouldn't go there.
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Stan

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Re: ESC Suggestions
« Reply #18 on: October 12, 2020, 08:51:51 PM »

It is a big beefy motor once again were losing the plot the ordinal question was what E S C do I need no mention of a battery only a 12 volt gel cell will be used. the question on the E C S has now been sorted.


Stan
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Seacommander

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Re: ESC Suggestions
« Reply #19 on: October 12, 2020, 11:07:50 PM »

Hello all,
Well that caused some ripples.
I got the boat inexpensively with the idea of using it as a go to boat, a bit of fun and not to serious, also remembered them from long ago.  A good T cut and it looks great.

When I posed the question, I was hoping that someone would say, I had a so and so in one for years, or Iíve a Sea Queen running similar, have a look at this product. Obviously ESC are still a hot topic of discussion.  Iím using the battery because I have some and itís an old 27mg radio, but itís OK.

I must thank Stan for his commitment and dedication, thanks so much. I will look at all of the suggestions and options and make a choice.

The boat worked pretty much out of the packing, so a quality Controller is not unreasonable. I put a very cheap Chinese thing in,  but donít like it, itís not smoking yet, but itís not as it should be. Thatís why I asked the question

Again thanks for all of the comments made

Cheers

Mark
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DaveM

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Re: ESC Suggestions
« Reply #20 on: October 12, 2020, 11:12:12 PM »

Avoid anything that's a) Chinese; b) Blue, or c) claims a continuous current capacity of 320 Amps. Avoid ESPECIALLY anything which is all three.
DM
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Taranis

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Re: ESC Suggestions
« Reply #21 on: October 12, 2020, 11:20:44 PM »

Good advice Dave  %%  However it is increasing difficult to identify anything that isn't made in China. People keep saying buy British but I think they really mean buy Chinese from a British shop if they think about it.
The radio control sector would be FUBAR'd without China  <:(


Very grateful for Scottish Whisky  :-)
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