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Author Topic: 6 volt or 12 volt?  (Read 2002 times)

theboatcrew

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6 volt or 12 volt?
« on: April 26, 2014, 02:21:58 PM »

Folks


A little advice needed for a recent project please.


I have a 48" long HMS Bulldog hull with twin 40mm propellers.  I have recently fitted two Electronize 545-12 motors controlled by two Electronize ESC's (one FR12X and one FR12VR). I am looking for scale speed with a reasonable run time.


My question from you electric experts out there is:-
Should I run the set up at 12 volts or 6 volts as I have the option to use either having lead acid batteries in both voltages (12 volt being 7ah and 6 volt being 10ah). I know the 12 volts will give me higher revs but are there 'electronic' reasons why either would be better.  Or is it just a case of try them both and see what performs best?


Any advice gratefully received.


Regards


Graham
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sparkey

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Re: 6 volt or 12 volt?
« Reply #1 on: April 26, 2014, 02:59:02 PM »

 :-)) I would go for the 12v option,might give you faster speed but will give you longer run time,ohms law again I am afraid,just throttle back a little,anyway always handy to get you out of trouble,Ray :-)) .
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Netleyned

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Re: 6 volt or 12 volt?
« Reply #2 on: April 26, 2014, 03:47:06 PM »



Personally I would try both.
But, In a hull that size You should have enough room
for any batteries of you choice.
I spent sometime on Fawn and I think 18 K ts is the limit.

Ned
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theboatcrew

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Re: 6 volt or 12 volt?
« Reply #3 on: April 26, 2014, 04:12:50 PM »

Hi Ned


18kts sounds right, with four Lister 'Black Pigs'....... (Sorry Blackstone ERS8M's), as her prime movers she would not have gone much faster.


You are lucky to have served on such a lovely ship, my last one had aircraft landing on it. :o  Never did get any time on 'smaller' ships.


Graham
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theboatcrew

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Re: 6 volt or 12 volt?
« Reply #4 on: April 26, 2014, 04:20:19 PM »

Thanks for the advice Sparky, I will probably try starting with the 12 volts as you suggest and see how she goes.


Graham
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Netleyned

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Re: 6 volt or 12 volt?
« Reply #5 on: April 26, 2014, 04:23:45 PM »

Graham,
I spent a lot of time with paraffin pigeons landing on my roof.
Eagle Centaur Victorious.
Better times with droggies
on survey duties.
Small  Woodlark and Echo.

Ned

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theboatcrew

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Re: 6 volt or 12 volt?
« Reply #6 on: April 26, 2014, 05:31:54 PM »

Ned


Recognised Echo from her crest as your aviatar, I was on Eagle also, 69 to 71.  You have served on some fine vessels there sir.


Graham



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malcolmfrary

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Re: 6 volt or 12 volt?
« Reply #7 on: April 27, 2014, 10:37:42 AM »

:-)) I would go for the 12v option,might give you faster speed but will give you longer run time,ohms law again I am afraid,just throttle back a little,anyway alway's handy to get you out of trouble,Ray :-)) .
Not at all sure about longer run times at higher voltage unless different motors are fitted.  Using Ohms law, into the same load, higher voltage gives higher current, higher current from the battery discharges it faster.  A lot of restraint on the throttle would be needed to keep the power used the same, but having a turbo boost can be handy.
One of the more important things to consider when settling on a main battery voltage is figuring out what other items you need to power.  What voltage will they require?
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More Coffee

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Re: 6 volt or 12 volt?
« Reply #8 on: April 30, 2014, 03:15:40 AM »

40mm prop on that motor is a good load.

For what it is worth. I found this

https://www.greathobbies.com/shipmodels/about_msw.php

pay attention to the R/C gear section.

Yorkshireman I believe is equipped with 45mm props..

And speaking from experience ,having a trawler with a 40mm prop and a Mabuchi motor. 12v is a reasonable start . just bare in mind that a lot of full throttle action will heat the motor up substantially , that was with 9.6 volt.
12v would load it up a little more ,
The advantage would be better bottom end slow speed, and a little more grunt at the top end. All of this would depend on the batteries,the condition ,discharge rates ,and amp hour rating.
It would be wise to tread lightly at first with frequent checks of the battery and motor temp. Generally speaking ,if your motor isn't getting beyond 80Celcius , its doing fine, If the batteries are feeling more than luke warm , its cause for concern.

The jest is ..start slow and easy and work your way into it , anything that gets hot , never hurts to ask , MHO 80C isn't that bad for for a motor or ESC.
 the SLA batteries ...hot ... shut it off... ok2

Please bare in mind  lead acid batteries don't like to be left in a discharged state , charge them after every run . And never run them down to the point where your ship is struggling. They don't always like to be deeply discharged.
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