SSR's and marine use

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Hoping sam am I will see this

going to use two Fotek SSR-100's
https://www.amazon.com/gp/product/B07PFDJQLV

their data sheet is about as useful as a turd-flavored lollipop http://www.fotek.com.tw/pdf/SSR-DD.pdf

Anyhoooo........

anyone have actual experience with the Fotek brand. I know Sam is using SSR's for the downriggers, however brand was not specified.

the trigger side draws 12mA, which should allow extended over-nights when running on the house batteries

plan on two of these sitting on top of heat sinks triggered on the accessory circuit side of the key switch. This is primarily for when I forget to turn the 0-1-2-both battery switch to off

one SSR will be fed from the starter terminal and will power the cabin lights, docking lights, the courtesy lights, swim lights, etc. there is a 50 amp circuit breaker at the battery feeding the 8 AWG cable up to this.

the engine, ignition feed and the accessory feed will be controlled by the 0-1-2-both battery switch

ignition side of the switch is powering VF4 relays at the engine for fuel/start/ignition coil/start interlock, and two VF4 relays at the dash powering nav lights, horn and dash lights. the ignition switch is fed by the 10 AWG wire running back to the engine in the original harness to a 50 amp circuit breaker.

the second one will be fed by the house batteries directly via a 4 AWG cable that cable goes back to a 100 amp breaker at the batteries. this will power the stereo, amp, washdown pump, inverter for the wife to plug in a hair drier or straightener (or a laptop). there will also be cabin lighting and ventilation fans. the trigger side will be fired by the accessory signal from the switch. that way if I forget the amp or inverter on, they go off when I pull the key from the ignition.

Bilge pump is wired so that the Auto side goes straight thru to the battery buss, and the manual side goes thru the accessory side power. this small battery buss goes thru the 0-1-2-both switch, however I may move that to battery hot for times when anchored and the battery switch is on "off"

Blower is wired to the battery buss after the 0-1-2-both switch

each circuit has appropriately sized ETA circuit breakers (new)

I know that a suppression diode is sometimes needed to de-energize the SSR's. I also know thru reading that some SSR's have gone up in spectacular flames when run at the higher end of their rating. the solder melts off the mother board and then the trace burns up in a glorious release of magic smoke

Any one see a flaw?

if they simply fail on the water, my current plan is simply move the wire over.

My backup is a pair of 225 amp Trombetta contactors https://www.trombetta.com/wp-content/uploads/2019/07/bear-family.pdf, however at 7.7 ohms, they would draw a bit of power (about 1.7 amps)

I sketched it up in the attached PDF

View attachment wiring.pdf
 

sam am I

Commander
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Jun 26, 2013
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2,169
The design looks like it should work fine but, those type SSR's I haven't ever used. The Fotek's star rating/reviews are mixed, not sure about these for your app.

Of the few reviews, more bad then good looks like, over heating easy and such. That said, these especially might not handle the inverter side current too well.

Yes, I use these on 4 X 10A lectric downriggers, use a acc switch on the dash to control their power feed, similar to what your doing....but more of an inductive load beings they're all motors.

These are waaaay tough, built-in output protection diode and such, never have felt the even get slightly warm (Very low R on) but, do have them on heat sinks. See spare below.

Click image for larger version  Name:	20191126_180015 (1).jpg Views:	1 Size:	556.9 KB ID:	10817114


Data sheet here
 
Last edited:

dingbat

Supreme Mariner
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Nov 20, 2001
Messages
16,068
Not sure what the goal is and how it relates to the battery switch.

If your doing what I think you are, I would use a voltage sensed isolator to control the load center(s) rather than introduce additional points of failure with separate remote control schemes for each circuit.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,536
I dont want high current going thru the ignition switch. hence the schematic I posted earlier.
 
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