Remote Starter Solenoid and Battery Disconnect Contactor

[rv_safetyman]

I am asking these questions for a business project, but hopefully the answers will apply to our buses.  Besides, this forum has the best brain trust I have ever seen.

The background is that we have developed a new fire detection system for a company that will sell it into the huge industrial market (he is coordinating the suppression part of the system with the vendor of our suppression system).  He has a customer who wants to shut down all battery power if there is a fire.  That is a huge challenge.

Clifford has stated that a Detroit starter can take 900 amps.  That means that a disconnect (relay/contactor) has to huge.  

My approach is to divide the loads into separate circuits that can be shut off by the auxiliary relay in our system.   I have done a ton of searching, but have not found a good answer.  My approach is to put a remote starter solenoid right next to the battery (think Ford firewall mounted solenoid on steroids).  That relay/contactor/solenoid can be a non-continuous device.  Putting that in the system would make all high amperage cables to the starter dead except for starting.  I can't find any solenoid with a 12V trigger with 900 amp capacity.

The application would then have a second large capacity power feed for all other electrical components.  On the types of vehicles we are talking about, that could be as much as 300 amps, perhaps more.  I have tried to find a 12V triggered continuous duty contactor with that capacity.  I have found some candidates, but would love to see if any of you have any thoughts.

The system would also have separate leads for the engine ECM (will use a timer relay to shut off after something like 30 seconds) and a separate lead for flashers for on-road vehicles that will turn on the flashers in the event of a fire.  Right now, most of the applications are off-road.

Yes, fuses/breakers would offer some protection, but the customer wants the system to shut off the power.

I think all of this would be great on our buses, if we can find components that are not hugely expensive.  Studies suggest that there are a lot of high current (primarily battery cable size) electrical fires in buses and trucks.

Thanks for the help

Jim

[luvrbus]

Jim, look at www.texasindustrialelectric.com at the relay section those guys can fix you up


good luck

[rv_safetyman]

Clifford, those folks come up in every search.  I have searched their website and don't find anything with the current capacity that I need.  Some come close, but with a 28 volt coil.  I will try to call them and see if they have some thoughts.

At some point in time I want to see how hard it would be to remote mount a DD starter solenoid close to the battery.  That solenoid would only be used as a switch to send current to the regular starter solenoid.  Anyone have a good close-up picture of their starter?

Jim

[eagle19952]

So if I understand this,
you have an "abundant" supply of 12vDC....and 110vAC is not desired/available.....
If then the rated contactors that you can source are operated by 24v DC coils, .....so if the disconnect is from a continuous duty "make" contactor, then the actuation of the disconnect would be momentary so that some other input after "incident" would re-establish "make",
then you could use this transformer in the "chain" of events to accomplish the 24v need.

http://www.solidapollo.com/12v-dc-to-24v-dc-step-up-transformer.html?gclid=CNvD1vW0mKkCFcLr7QodO2vdsw


Are you offering consult royalty.....

[rv_safetyman]

Eagle19952, that would solve the issue of the coil voltage.  Kind of an overkill, but I think there are smaller units.

I am still thinking out loud about mounting a DD starter solenoid on a pad and using it as the shut-off for the starting circuit (the most demanding).

As far as consulting fee, the way I tend to run my business is to loose money on each part, but make up for it with volume .  Does not leave anything to spread around.

Jim

[Joe Camper]

Prevo uses a big honkin solonoid for the cassis battery disconnect on the XLII

A simple toggle switch signals a standard bosch relay that triggers a massive solonoid. It is mounted very close to the batteries and they are very close to the starter in the back right door there.

Lower on the same panel are the 12 and 24 volt breakers for the front and rear feeds

I do not know its capacity. its about half the size of the previous photo has no fins. 2 big lugs and a small terminal. It has the ability to switch 4 8-D chassis batts but I think you have bigger or other issues if I understand what your trying to do.

[eagle19952]

I am still thinking out loud about mounting a DD starter solenoid on a pad and using it as the shut-off for the starting circuit (the most demanding).



Kind of an overkill, but I think there are smaller units.

Size 8-2/8" X 3" X 4-6/8"
You pays and you gets for whats you pays....

[Len Silva]

Finding a continuous duty solenoid in the 1000 amp range is going to be a challenge and quite expensive.

There are DC circuit breakers in that range used in telephone power plants, but also pricey and you would need to develop an actuator of some kind.

So, how about a one time use device that opens the circuit, perhaps with explosive bolts or a CO-2 cartridge.  You would have to develop the device yourself but it might find a market in lots of new places.  Much of the hardware might already be available in the fire suppression industry.  I'm thinking specifically about the explosive devices that were used to discharge Halon systems in the past.

It seems to me that using a solenoid for an operation you hope never happens might not be the best way.

Here is a DC breaker/disconnect with shunt trip, but I would guess that it is several thousand dollars.
http://www.eeeusa.com/products/bd

[stevet903]

Jim - did you consider using multiple contactors in parallel?   Connect the inputs and outputs with a copper bus bar and make the connections to the bus bar?

Or maybe this is what you are looking for?

http://www.texasindustrialelectric.com/relays_1119865.asp

Or something on this page?

http://www.texasindustrialelectric.com/relays.asp

Steve

[rv_safetyman]

Bingo!!  Steve is the winner so far.

I thought I had "searched" that website, but somehow I missed the 1500 amp starter relay.  That will take care of the start load and let us concentrate on the circuit for the rest of the loads.

In the second link, I took a quick look and I see that they have a normally close, continuous duty 150 amp relay.  I will spend a bit more time looking at that link - sure wish they had true search feature.

I am hoping to find a relay/contactor that is normally closed, continuous duty and in the 300 amp range. 

Thanks, as usual, for all the great help!!!

Jim

[artvonne]

  The 686-905 relay is a 12 volt normally open relay rated at 500 amps continuous/1200 inrush.

[stevet903]

You could always make a signal inverter with a cube relay to make the normally open contactor normally closed.  If you google for the Bosch Relay Application Book, it has a number of handy applications, mostly aimed at the car alarm and stereo installers,  including the signal inverter.

Steve

[JWallin]

300 amps continuous at 12 volts is only 3600 watts, or about 1/2 horsepower. You might consider using a power mosfet, there are many options that can handle significantly more than that with minimal dissipation, and can be easily integrated into a digital control scheme. If you're making a commercial product, you may consider a more modern approach than a contactor.

[rv_safetyman]

JWallin, interesting.

I only have a fleeting knowledge of mosfet technology.  Can't quite picture that technology with 300 amp capacity.  That takes big cables and not sure how that all fits together. 

I will have to do my homework.

Thanks, Jim

[JWallin]

Jim, check out welding and/or motor control topologies. You just need enough copper conductor to support your continuous load requirements with some safety margin. There are a number of ways to get at it, depending on your overall design constraints. One possibility is multi conductor cable utilized in parallel to spread the load on you pcb interface.