[PSUBS-MAILIST] rpm

Sat Aug 30 11:01:18 EDT 2014

Alec,
I do not have equipment able to test the amp draw, I did put a load on the motor to check how much heat build up there was on the power leads.  The temp gain was minimal. 
Hank--------------------------------------------
On Sat, 8/30/14, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] rpm
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Saturday, August 30, 2014, 10:36 AM

 That's
 an interesting test Hank. and I wonder whether someone with
 more motor knowledge than I could infer an efficiency figure
 from the speed reduction. It's tempting to say 10%, but
 I imagine that would be simplistic, assuming the test was in
 an unloaded condition. Do you have any way of running the
 same test in a tub or with the thruster immersed, and
 measuring the currents?   

 Thanks,
 Alec

 On Sat,
 Aug 30, 2014 at 9:22 AM, via Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

 Hank,

 I don't know if you will find an oil with lower
 viscosity than WD40.  
 The problem with WD40 is that it is a solvent that damages
 plastic and rubber 
 components within the motor.  Alec Smyth did a lot of
 testing on various 
 oils.  The last I knew the medium of choice was Marvel
 Mystery Oil.  
 It's safe for the seals, etc., and has a lower viscosity
 than any straight 
 mineral oil.

 For thrusters, comparative amp draw at a given RPM
 (with associated heat 
 build-up) is probably more significant than drop in maximum
 RPM since we're 
 not generally operating at maximum.  That might not be true
 when you're 
 using the motor to operate a pump.

 Jim

 In a message dated 8/30/2014 5:51:09 A.M. Central
 Daylight Time, 
 personal_submersibles at psubs.org
 writes:
 Brian,
 Yes, I
 have heard others have had good success with 
   different oils.  Maybe the rpm drop is less with other
 oils.  

 Hank
 --------------------------------------------
 On Fri, 8/29/14, 
   Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>

   wrote:

 Subject: Re:
 [PSUBS-MAILIST] rpm
 To: "Personal
 Submersibles 
   General Discussion" <personal_submersibles at psubs.org>
 Received: 
   Friday, August 29, 2014, 11:26 PM

 Hank, There is a very thin 
   mineral
 oil that might be better that the
 wd 40

 Brian

 --- 
   personal_submersibles at psubs.org
 wrote:

 From:
 hank pronk via 
   Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal 
   Submersibles General Discussion 
   <personal_submersibles at psubs.org>
 Subject: Re: [PSUBS-MAILIST] 
   rpm
 Date: Fri, 29 Aug 2014 13:23:31
 -0700

 Vance,
 Yes for sure, 
   Gamma has two separate amp gauges, one for the
 motor and one for the rest 
   of the sub. All 24v and the
 trolling motor
 is 12 v
 Hank 

 --------------------------------------------
 On Fri, 8/29/14, via 
   Personal_Submersibles 
   <personal_submersibles at psubs.org>
 wrote:

 Subject: Re: 
   [PSUBS-MAILIST] rpm
   To: personal_submersibles at psubs.org

   Received: Friday, August 29, 2014, 4:03 PM

   Yeah, 
   too
   simple. Maybe that's a good
 guess, but..... I will say

   that an ammeter in the boat is a good thing. You can
 keep
 an
   eye 
   on things, and if it goes UP at some stage, you would
   suspect a 
   thruster issue (a tangle, or a bearing failure
 or
   whatever). All 
   it takes is an appropriate shunt and a
 gauge
   (in my pre-digital 
   steampunk mind). Okay, thanks anyway. I

 was curious, that's 
   all.
   Vance

   -----Original
   Message-----

   From: hank pronk via
 Personal_Submersibles

   <personal_submersibles at psubs.org>

   To: Personal 
   Submersibles General Discussion

   <personal_submersibles at psubs.org>

   Sent: Fri, Aug 
   29, 2014 3:56 pm

 Subject: Re: [PSUBS-MAILIST] 
   rpm

   Vance,
   I did not do an 
   amp draw test because I do not have the

 technology in house. I 

   would guess with a 10% rpm drop, there
 may be a 10% amp

   increase. That would be 
   to simple
 :-)

   Hank

 --------------------------------------------
   On Fri, 
   8/29/14, via Personal_Submersibles 
   <personal_submersibles at psubs.org>

   wrote:

   Subject: Re: [PSUBS-MAILIST] rpm
   To: 
   personal_submersibles at psubs.org
   Received: Friday, August 29, 2014, 
   3:39 PM

   Hank,
   Did you check the amperage? I 
   wonder if the
   resistance causes a
 higher draw, and if so, 
   how
   much?

   Vance

   -----Original

   Message-----

   From:
 hank pronk via 
   Personal_Submersibles

   <personal_submersibles at psubs.org>

   To: 
   personal_submersibles

   <personal_submersibles at psubs.org>

   Sent: Fri, Aug 
   29, 2014 3:33 pm

 Subject: [PSUBS-MAILIST] rpm

   I am working on a
 hydraulic
   pump that will be 
   external and pressure compensated 
   in
 oil.  I am using a 
   trolling motor to drive
 the pump.  A
   while back there was 

   a question about rpm drop when a
 trolling motor 
   is
 filled
   with oil.  I
 bench 
   tested that today, 
   and the motor runs at 2,000rpm
 stock
 and
   1,800 rpm full of 

   WD40.
   Hank

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