Model Boat Mayhem

Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: Trucker on February 12, 2020, 07:42:51 PM

Title: ESC for Brushed motor
Post by: Trucker on February 12, 2020, 07:42:51 PM
Hi Guys
looking for a little conformation that i have understood what i have read;

1. I'm going to be running two 500 motors connected to one ESC,
2. my battery power will be 12v,
3. therefore, each motor has a 2.7amp load with a stall 21amp,
4. each ESC current at double the load amp 5.4, = 10 amp controller,
5. but because i have two motors on one esc, a 20amp controller will be required,
6. Will a 15 amp fuse to protect the esc?

Trucker

   ( Edit. Admin )

Original post
Hi Guys
looking for a little conformation that i have understood what i have read, im going to be running two 500 motors connected to one ESC, my battery power will be 12v,
so, each motor has a 2.7amp load with a stall 21amp, to decide my ESC # double the load amp 5.4, = 10 amp controller, but because i have two motors on one esc, a 20amp controller will be required, with a 15 amp fuse to protect the esc.
Title: Re: ESC for Brushed motor
Post by: malcolmfrary on February 12, 2020, 10:30:24 PM
More or less that, yes.
It is a GOOD IDEA to fuse the individual motors when running more than one motor from a single ESC.  The only time it really is a good idea to have a fuse between motor and ESC.  The one between the ESC and battery does nothing to protect the ESC.  If something happens in the ESC to cause the fuse to blow, its too late.  It is protecting the boat against the battery in that case.
If you look at - [size=78%]https://www.modelboatmayhem.co.uk/forum/index.php/topic,6169.0.html (https://www.modelboatmayhem.co.uk/forum/index.php/topic,6169.0.html)[/size] - useful information is there.  It is an old thread, but true then is still true now.
Title: Re: ESC for Brushed motor
Post by: Trucker on February 13, 2020, 03:40:44 AM
 :-)) thanks, i have read the link you showed , picture paints a thousand words,
Trucker
Title: Re: ESC for Brushed motor
Post by: RST on February 13, 2020, 08:55:05 AM
I'm not too convinced on your rationale. Is it an mtronics 500 motor?  The website says start-up current for that is about 15a. Personally I go more by stall currents. Unlikely you'd have both stall at same time but according to mtronics anyway 2 motors off one esc could see a short term peak of 30a.  Just my personal opinion but if it were me id fit a bit bigger ESC. From memory I fitted a viper marine 20 or 25 in my pilot boat running a single mtronics 500 although it's not been on the water just yet. And I agree, bog std advice with 2 motors off one esc is to fuse each motor.


Rich
Title: Re: ESC for Brushed motor
Post by: Trucker on February 13, 2020, 11:16:26 AM
Both motors are Marine 500,brush
Title: Re: ESC for Brushed motor
Post by: Tug Fanatic on February 13, 2020, 01:34:20 PM
If it were me I would also go higher amperage on the Esc. 30A+ seems much more sensible and yes I would fuse each motor at somewhere between its full power load and its stall current.

I also note that you are using a 12v battery. Batteries normally give more than their rated voltage when fully charged. A 12v lead acid gives around 14.5v. This matters because an ESC that is rated at 12v maximum will not be at all happy with a 14.5v battery.
Title: Re: ESC for Brushed motor
Post by: Trucker on February 13, 2020, 05:22:44 PM
thanks for all your pennies worth, theres more chew over than i thought, just when i thought i was getting there  ok2


Trucker
Title: Re: ESC for Brushed motor
Post by: microgyros on February 13, 2020, 06:40:19 PM
thanks for all your pennies worth, theres more chew over than i thought, just when i thought i was getting there  ok2


Trucker
But if you disable the bec and use a decent receiver pack then you are all right at 2.7 amp/motor and even with a 20 volt battery!

You could go better with a 3 amp resettable fuse (https://www.ebay.co.uk/itm/16V-3A-4A-5A-6A-7A-8A-9A-10A-11A-12A-14A-PPTC-Resettable-Fuse/232445358290?) per motor. These are normally conducting fuses that switch to high resistance at 4.5 amp (or x 1.5 rated 3 amp) The resettable fuses remain in that state until you remove throttle or load current, which has fallen to a fraction of one amp.

I've recommended the first step to several Mayhemmers who contacted me about stop-start problems with the brand you are considering on 12 volt. They were experiencing a thermal cut out because the linear bec is dissipating excess heat to the tune of (Vin-Vbec x bec current) in Watts. That is much more than heat from drive transistors and cables at 3 amp.
Title: Re: ESC for Brushed motor
Post by: RST on February 14, 2020, 08:05:37 PM
I cant be the only person keeps re-reading previous post and cant work that one out ref the OP's question?


Rich
Title: Re: ESC for Brushed motor
Post by: Martin [Admin] on February 14, 2020, 11:39:38 PM
 
Edited OP   :-)
Title: Re: ESC for Brushed motor
Post by: Tug Fanatic on February 15, 2020, 11:29:03 AM
Please see, and hopefully answer, my question about using resettable fuses here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,64475.msg683269/topicseen.html#msg683269 (https://www.modelboatmayhem.co.uk/forum/index.php/topic,64475.msg683269/topicseen.html#msg683269)