Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-01-2015, 13:28   #1
Registered User

Join Date: Sep 2013
Location: Alert Bay, Vancouver Island
Boat: 35ft classic ketch/yawl.
Posts: 935
Images: 4
Send a message via Skype™ to roland stockham
Question Autopilot control, Solid state relays

Hi all
I am fitting a new below deck autopilot using the Octopus pump which draws about 20a max. My current computer (Raymarine XP5) has a peak out put of about 6A but works very well.

So decided to simply control the pump using a paid of external relays. Solid state seems to be the way to go. All seamed fine until I tried to actually buy the relays!

Electromechanical relays are no problems, 12v control circuit and enough amps on the output but does no care whether it is AC or DC

Looking at the spec's for SSR's there are plenty with 12v DC control imputs but most of them seam to be 30-240v AC on the switched circuit. I can't find any information about whether that means they will swtch a low votage DC load as well. Anyone now how these things work?
__________________

__________________
roland stockham is offline   Reply With Quote
Old 18-01-2015, 13:41   #2
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Autopilot control, Solid state relays

Try www..crydom.com

The AC units will not switch DC , they use SSR , the DC ones uses mosfets

You need to spec these SSRs carefully, they can be fragile electronically , carry spares !

Dave


Sent from my iPad using Tapatalk
__________________

__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-01-2015, 14:17   #3
Registered User

Join Date: Sep 2013
Location: Alert Bay, Vancouver Island
Boat: 35ft classic ketch/yawl.
Posts: 935
Images: 4
Send a message via Skype™ to roland stockham
Re: Autopilot control, Solid state relays

Thanks Dave. Given that they are 4x the price of standard automotive relays do you recon they are worth it. I can get machanical relays and 2 spares for about $20 (and replacements at any auto shop). 2 SSR's plus one spare will be close to $70 and spares are order only. Which would you opt for?
Autopilot is critical as I may be sailing Panama to Hawaii SOLO this summer (do have a windvane as well)
__________________
roland stockham is offline   Reply With Quote
Old 18-01-2015, 14:20   #4
Registered User

Join Date: Jun 2010
Posts: 392
Re: Autopilot control, Solid state relays

You are going to need four relays and a couple of diodes for an H Bridge.
__________________
olaf hart is offline   Reply With Quote
Old 18-01-2015, 14:49   #5
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: Autopilot control, Solid state relays

I did the very same mod. I used relays at first but after reviewing the specs on the power transistors did away with the relays.

I have since put a 1000+ miles on the autopilot without a hitch.

When testing prior to doing away with the relays I never saw more than 4 amps on the pump.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 18-01-2015, 15:42   #6
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,400
Images: 1
Re: Autopilot control, Solid state relays

Google Comnav Marine CT2 motor controller.
There is a used CT3 on ebay cheap at present-not sure if it will work for ur situation,but I think it can be modified to.
Cheers / Len
__________________
My personal experience & humble opinions-feel free to ignore both
deblen is offline   Reply With Quote
Old 18-01-2015, 16:18   #7
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: Autopilot control, Solid state relays

The MOSFET's are IRFZ48NS.

Data sheet here

http://www.irf.com/product-info/data...a/irfz48ns.pdf
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 18-01-2015, 16:20   #8
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Autopilot control, Solid state relays

Quote:
Originally Posted by roland stockham View Post
Thanks Dave. Given that they are 4x the price of standard automotive relays do you recon they are worth it. I can get machanical relays and 2 spares for about $20 (and replacements at any auto shop). 2 SSR's plus one spare will be close to $70 and spares are order only. Which would you opt for?
Autopilot is critical as I may be sailing Panama to Hawaii SOLO this summer (do have a windvane as well)

In general , good quality relays will be ok , personally I'd use solid state

Is yours a constant running pump or a reversing one. ,?

Dave


Sent from my iPad using Tapatalk
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-01-2015, 16:51   #9
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Cbreeze
Posts: 346
Re: Autopilot control, Solid state relays

Most modern autopilot controllers use pulse width modulation to achieve variable speed control of the DC drive motors. You can have a bang/bang control of the driving motor, it is just a lot harder on the components. Might want to look at the actual motor drive signal before choosing a higher power output stage. Amplifier might give more satisfactory control vice relay.
__________________
Frankly is online now   Reply With Quote
Old 18-01-2015, 17:38   #10
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Autopilot control, Solid state relays

Quote:
Originally Posted by Frankly View Post
Most modern autopilot controllers use pulse width modulation to achieve variable speed control of the DC drive motors. You can have a bang/bang control of the driving motor, it is just a lot harder on the components. Might want to look at the actual motor drive signal before choosing a higher power output stage. Amplifier might give more satisfactory control vice relay.

You can set nearly all APs to control directional only not speed for constant running pumps etc that signal can be used.

But I agree a look at the waveform would be helpful. I don't remember the Raymarine APs bring pwm though

Dave


Sent from my iPad using Tapatalk
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 19-01-2015, 00:34   #11
Registered User

Join Date: Sep 2013
Location: Alert Bay, Vancouver Island
Boat: 35ft classic ketch/yawl.
Posts: 935
Images: 4
Send a message via Skype™ to roland stockham
Re: Autopilot control, Solid state relays

Thanks Olaf I looked up H bridges and found these which seam ideal Robot Power Products - Simple-H & HV - H-bridge. Much simpler than trying to make my own and cost about the same
__________________
roland stockham is offline   Reply With Quote
Old 19-01-2015, 06:49   #12
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Autopilot control, Solid state relays

Cockpit Pilot SPX-5 and Hydraulic Pump Possible ?

Pm sent.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 19-01-2015, 12:39   #13
Senior Cruiser
 
CLady's Avatar

Cruisers Forum Supporter

Join Date: Jan 2013
Location: Seattle
Boat: C&C40T 1980
Posts: 180
Re: Autopilot control, Solid state relays

I don't know how those relays work. I have a 15 year old Autonav hydraulic drive (equivalent of the Type II drive size) hooked up to the steering quadrant with my new Raymarine EV 400 computer that I installed and really like it. In heavy conditions with lots of yawing, it drew max 20 amps and kept up with the boat's needs.

That Octopus unit looks good.
__________________
CLady is offline   Reply With Quote
Old 19-01-2015, 12:45   #14
Senior Cruiser
 
CLady's Avatar

Cruisers Forum Supporter

Join Date: Jan 2013
Location: Seattle
Boat: C&C40T 1980
Posts: 180
Re: Autopilot control, Solid state relays

My question would be if they are marine grade switches.
__________________
CLady is offline   Reply With Quote
Old 19-01-2015, 13:49   #15
Registered User

Join Date: Jan 2015
Location: My yard, Tucson, AZ
Boat: Windward Marine Searaker 50
Posts: 42
Re: Autopilot control, Solid state relays

I've looked at the exact same project, X5 AP connected to Octopus HLA. I looked at a lot of options for relay and came up with the Crydom DP4R60D20. Its a DC Reversing Solid State Contactor
Ratings of 20, 40 & 60 Amps
Load voltage ratings of 1-48VDC

A little pricey but seems like the perfect fit.

You can find a spec sheet on it here:

http://www.crydom.com/en/Products/Catalog/d_p4_r.pdf
__________________

__________________
wgoodbye is offline   Reply With Quote
Reply

Tags
autopilot

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Automatic Charge Relays - Good or Bad mlibkind Electrical: Batteries, Generators & Solar 54 10-10-2014 15:10
Question about Relays Dockhead Electrical: Batteries, Generators & Solar 26 15-10-2013 03:05
Solid State Relay Puzzle Dockhead Marine Electronics 41 09-05-2013 08:33
Simple Solar System Solid State Relay Design SunDevil Electrical: Batteries, Generators & Solar 1 27-02-2012 00:49
Impulse Relays svpresent Marine Electronics 4 18-12-2010 09:28



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:43.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.