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Solid State Contactors?

mstrauss

mstrauss

Well Known Member
Patron
I have never seen any discusion of using a solid state contactor for either the main or starter contactors. I know Vertical Power has the PPS, but never hear of anyone using just a contactor like the InPower Solid State Contactor.
This may not be the right solid state contactor for the application, but is there one?
 
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Here is an image of the SS contactor:
75929_primary_225px.jpg
 
The control circuit is really efficient but the main circuit has a big voltage drop and produces a fair bit of heat. If your alternator is down then it will be a big load on your limited battery life.
 
Blue sea makes one and several here use it for the main contactor. Main benefit is low holding current draw.

Larry
 
It is very easy to have an efficient mosfet based switch for both the main contactor and the starter. One for a dollar will pass 20amps - it’s when you start and want full start current that it has to be beefier.

This is a good example. It says it will take over 200 amps for a few dollars. It will have to have an appropriate heat sink.
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46269e1c019016a501c81dd0f7e

The voltage drop across the mosfet is very low when on. It is a function of current based on a resistance of around 1 milliOhm. 1-2 volt at max current is a typical maximum. It is usually much lower. If you had 30A of ship load with no alternator this mosfet would have about 0.03 volt drop.

One feature of this is that the circuit is not completely open when off. There is a 2 mega ohm resistance so the drain is very low, but it is not zero. Mechanical contactors are truly open when off. There is no parasitic drain of any kind with a mechanical contactor. I hope we don’t have to care about EMP pulses but the mechanical one wouldn’t care. On the other hand, corrosion and fatigue failure don’t happen with MOSFETs. And I think if you got a cheap old stereo amplifier from someone the power mosfets on the back case are ripe for a contactor home brew.

For me the price point of the InPower is not amenable to my project.
 
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Very cool thread!

Maybe folks that are using these can post links and info about type (continuous duty, non-continuous) and ratings and their experiences?
 
GigaVac

I use the GigaVac line of contactors.

For my starter, I use the GigaVac GV142BAX. For batteries, I use the GV141BAX and then the GVB351BAX is perfect for a cross-feed contactor having bi-directional current interruption capacity.

This line of contactors have low drop out and pick up voltages at 8VDC and very low maintaining loads, so very useful with a battery in a discharged state. And at 12VDC with the loads a typical RV uses, their estimated MTBF is in the one million switching cycle range.

They can be bought in several different mounting and aux coil configurations and are perfect for harsh environments (e.g. they're used in several military applications including tanks and drones).

They're cost is about the same as a good quality Lamar contactor (common GA aircraft starter contactor) and I highly recommend them.
 
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The GigiVac and equivalent are not solid state contractors. They are mechanical contractors that have two coils that operate at lower current than standard contractors. Still an excellent choice.
 
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Mikeyb said:
The GigiVac and equivalent are not solid state contractors. They are mechanical contractors that have two coils that operate at lower current than standard contractors. Still an excellent choice.
Click to expand...

We have four Gigavac relays in our RV-10.

You can get Mil-Spec versions and you can also get one with an additional contact - which we used tied to a discrete input on the G3X for an CAS message when the crossfeed relay is closed. These contactors also have built in diodes so no need for outboard ones.

Great choice for an electrically dependent airplane.
 
I'm I missing something? Both the GigiVac and Blue Sea look to to use one or more coils, i.e. are mechanical contactors, not solid state.
 
Neither is solid state relay. They are mechanical.

I believe this went sideways by being confused with many older discussions.

The BS and GV coils being referenced are pulse width modulated versus EM force of a "traditional" coil. This affords much lower coil currents at a slight increase incomplexity; hence, the old debate.

Having true SS coils available for our applications that meet the specs of the existing stuff would be neat.
 
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