RE: [PSUBS-MAILIST] oil compensating and RPM

["Greg Cottrell" <greg@precisionplastics.com>]

Hi Emile,

The loss in RPM can be compensated for by increasing the voltage to the
thruster. You can increase the voltage on most DC brush motors without
damage as long as you monitor the amps and don't exceed the motors rated
current limit. I believe that the increased voltage also increases brush
efficiency when submerged in oil. With a PWM controller you can use 24v to
power the 12v motors as long as you set the speed limit with an ammeter.
With less advanced controls you could probably just use three 6v batteries
in series for 18v without any problems- but watch the amps! The fact that
these motors are filled with a lubricant that conducts heat helps to keep
the temp down with the increased voltage.



Greg Cottrell
Project Manager
 
 
greg@precisionplastics.com
http://www.precisionplastics.com
 
P please consider the environment before printing this email 
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Emile van Essen
Sent: Sunday, May 02, 2010 3:27 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] oil compensating (was hello emile)

Greg, Frank . Thanks for the info! Really useful.


Alex,

Probably your oil is too thick. It is pity that viscosity is hard to measure
and we talk about "very thick" or "thin as water"

With WD 40 Oil(ish) I measured  just a 10-12 % loss in RPM
With a "reasonably thin" silicone oil (Dot 5 brake fluid) I measured a loss
of 60 % RPM

However flammable, even with a partial filled engine the brush sparks would
not ignite the WD40.

Mmm Greg dou you also know the viscosity of WD 40??

Good luck!
Emile
the Netherlands

-----Oorspronkelijk bericht-----
Van: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] Namens Alex
Verzonden: zondag 2 mei 2010 15:08
Aan: personal_submersibles@psubs.org
Onderwerp: RE: [PSUBS-MAILIST] Hello Emile

I don't understand how the brushes work if they are full of oil! I got oil
on a
motor once and it slowed way down and started pulsing on and off because the
oil
on the brushes made it in to an insulator when it started to spin up. How do
the flooded trolling motors work?

Alex


On 30-Apr-2010 Greg Cottrell wrote:

-- 
Mailed with XFmail on 02-May-2010.
God saved Noah, but Noah had to build an ark!



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