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Old Aug 11, 2011, 07:25 PM
leaky bill
Parksville BC
Joined Jul 2007
215 Posts
Help!
Johnson 550 motors ?

I would appreciate hearing from someone with experience running
John son 550 motors.

I am building a 37 inch fast patrol boat and plan on installing two Johnson 550 motors, I believe the motors are designed for a 6 volt system
Questions
1. Will I burn out the motors running on 12 volts ?
2. Which ESC should I use, I am planning on a proboat 40 amp ESC but
do not know if that ESC is compatible for a 6 volt system...will it support the load from these motors ?

My boat will be a very light GRP hull with a 5ah SLA battery for power and ballast.
TIA
Leaky Bill(ge)
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Old Aug 11, 2011, 07:50 PM
"Unnecessary Necessity"
coriolan's Avatar
Canada, QC, Quebec City
Joined Sep 2006
5,811 Posts
Johnson 550 don't draw very much and two should be Ok on a 40 Amps ProBoat esc and 12V as long as not overproped or use a geardrive reduction(best). If they really have a winding for 6V only you can alway feed them in serie from the esc, each will see only 6V and the Amp draw will remain the same. Most of these Johnson/Mabuchi motors don't have a fixed voltage rating, the only limit is the total Watts through the armature which depend on the load.
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Old Aug 11, 2011, 07:52 PM
太刀風
Tachikaze's Avatar
United States, OR, Eugene
Joined Jan 2003
1,090 Posts
Johnson makes several motors. My Springer runs on a Johnson 550 that is 6v. My Japanese DD runs on 12v with a completely different Johnson 550. The 550 refers to the cannister size of the motor.
If when you turn the shaft of the motor, and you feel it pull firmly through the magnets or if you can barely turn it with your fingers, I would recommend not running it on 12v.
Without playing with the motor, and if there are not markings on it, one can only really tell by hooking it up to power. Hook it up to 6v, it run like crazy? If so, then do not be using 12v.
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Old Aug 11, 2011, 09:11 PM
Registered User
North Central TN USA
Joined May 2006
3,611 Posts
A problem with series connections is if one motor gets bound up by say, seaweed, the second motor grabs all the power and smoke usually results.
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Old Aug 12, 2011, 01:34 PM
leaky bill
Parksville BC
Joined Jul 2007
215 Posts
Thanks for your replies

I will install the 550 motors using a 6 volt 5ah SLA battery...I am confident
that the model will perform well on a pond with 6 volts...however the only info I can find on the Proboat 40 amp ESC is reference to brushless motors...

Can a ESC designed for brushless motors be used for brushed motors with no
risk ?

TIA

Leaky Bill(ge )
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Old Aug 12, 2011, 02:32 PM
Tinkerer in Training
RGinCanada's Avatar
Guelph, ON
Joined Sep 2004
1,846 Posts
No, you will need a brushed motor ESC.

I am pretty sure that this Proboat 40A ESC is for brushed motors.
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Old Aug 12, 2011, 07:12 PM
NeverAgainVolunteerYourse lf
nick_75au's Avatar
Australia, QLD, Regents Park
Joined Mar 2007
3,723 Posts
Not quite true, It depends on the ESC, some of the brand name ESC's like Tekin and Novak have brushed and brush-less modes, 99% of brushless ESC's are brushless only.

They seem like a waste of money to me though

The Pro-boat linked is definitely brushed motor only

Nick

Etc
http://www.teamnovak.com/products/esc/gtb/index.html

http://www.amainhobbies.com/product_...-Brushless-ESC
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Old Aug 12, 2011, 11:20 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
2,353 Posts
unless specified, A brushless ESC is for brushless only.
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Old Aug 13, 2011, 03:03 PM
Registered User
Blackpool, Lancs
Joined Feb 2006
2,992 Posts
If a boat is wanted to be fast, a lightweight hull is great. Ballast isn't. Add more lightness.
Lead acid is not the best for performance, despite there having been reasonable examples. Think NiMH or Lithium batteries for performance and good run times for a given weight.
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Old Aug 13, 2011, 10:09 PM
"Unnecessary Necessity"
coriolan's Avatar
Canada, QC, Quebec City
Joined Sep 2006
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A "fast scale boat" isn't a fast electric racing boat, patrol boat are not planning hull but displacement hull and would look ridiculous zooming around (which a 37" scale hull powered with 550 size motors cannot do anyway). I have seen relatively fast scale boats around that size powered with brushed Astroflight-40 and 12V/7amp gel cell.
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Old Aug 14, 2011, 10:38 AM
Big Boats Rule!
boater_dave's Avatar
Wisconsin
Joined Jun 2007
2,039 Posts
The same question comes up often. A gel cell is not the best choice when the load is going to be more than an amp or two. The problem is that of heat dissipation. The life span of the battery will be cut short as the internal plates will be damaged. Only AGM (absorbed glass mat) or wet flooded lead batteries are capable of dischagrging at useful levels.
If you are going to draw more than an amp or two, NiCad/NiNmh or Lipo are much better suited. And they can be charged pond side for even longer runs. If your motors were made for 6 volt there should be no problem running them on 7.2 volts (6 cell NiXXX).
Do you know what the total amp draw is for your motor/prop combination?

Dave
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Old Aug 14, 2011, 01:57 PM
Nickel Belter
ZZ56's Avatar
Northern Ontario
Joined Jun 2009
865 Posts
Quote:
Originally Posted by boater_dave View Post
The same question comes up often. A gel cell is not the best choice when the load is going to be more than an amp or two. The problem is that of heat dissipation. The life span of the battery will be cut short as the internal plates will be damaged. Only AGM (absorbed glass mat) or wet flooded lead batteries are capable of dischagrging at useful levels.
If you are going to draw more than an amp or two, NiCad/NiNmh or Lipo are much better suited. And they can be charged pond side for even longer runs. If your motors were made for 6 volt there should be no problem running them on 7.2 volts (6 cell NiXXX).
Do you know what the total amp draw is for your motor/prop combination?

Dave
idonwanna start a fight, but a co-worker says gel-cells are fine up to their amp-hour rating but not beyond, and he's an electrician with 30 years experience.

Me, I've seen so many fine scale boats using your standard Yesa and Yuasa and Panasonic gel cells and not one owner reported killing their batteries after a hard run. What kind of damage are we talking about, a total loss of charge or a gradual decline in performance?
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Old Aug 14, 2011, 04:43 PM
leaky bill
Parksville BC
Joined Jul 2007
215 Posts
i have been sailing my 72 inch destroyer for the past 5 years, no problems running 2 x 12 volt 755 from a single 7ah SLA, normally my sailing sessions are over an hour...so will go with a 5ah SLA for my 37 inch patrol boat with displacement hull. The SLA battery should provide all the ballast I will need...
I will use 6 volt SLA battery...if that does not provide the speed I am
looking for, may try 12 volt, at some risk of course.

Thanks for the interest in this project
see my models on
www.freelanceboats.blogspot.com

Leaky Bill
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Last edited by leaky bill; Aug 14, 2011 at 06:35 PM.
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Old Aug 15, 2011, 12:58 AM
"Unnecessary Necessity"
coriolan's Avatar
Canada, QC, Quebec City
Joined Sep 2006
5,811 Posts
www.freelanceboats.blogspot.com

Nice build Bill!
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Old Aug 15, 2011, 11:28 AM
Big Boats Rule!
boater_dave's Avatar
Wisconsin
Joined Jun 2007
2,039 Posts
My comment on gel cells is about amp load. The damage comes from overheating the internal structure if too many amps are drawn from the battery. Overcharging causes the same issues. The typical damage is the battery will no longer hold a charge, so I guess you could say poor performance is the result. All of the examples everyone posted in with are just what I said in my post. If the load is only a few amps you should be fine. And the bigger the battery, the better it can handle the heat. Also the running style. Do you run at high speeds for a long time, or only short bursts. The original post said fast-ish boat on a pair of 550 can motors.
Go to any battery store, or website, and read the FAQ section on SLA/gel type batteries for this info. These batteries are best suited for smaller discharge rates and long term storage of power. NiCad and Nimh are good for dischage amps, but will self discharge at about 5-10 percent per day so they make lousy storage batteries. Lipo are great at both discharge and storage.
My 5 minute Google search found this site which has a nice combination of info and tech specs.
http://homepages.which.net/~paul.hil...eriesBody.html
It looks like the C rating is always fractional, even as low as 1/5 capacity of the battery itself. My question would be at what rate do you charge your battery? That should be close to the optimum discharge rate as well.

Dave
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