high current parts

Google up Digikey, Mouser or Newark electronics.

You can use a "Ford" starter relay(Solenoid), they do tend to get quite warm after a lot of use, but seem to tolerate that kind of service. Also be advised, #6 wire is a tad small for 80 Amps, #2 is more like it if you want to keep your voltage drop to a minimum.

80 Amps of current would be for a would be right for a 750 Watt inverter. You better have one hell of an alternator if your going to pull this kind of power for any amount of time. A 100 Amp alternator WILL NOT supply anywhere close to that around idle speed and WILL grenade itself it you try to pull that kind of current from it for any amount of time.

Hey Matt

Wow - 80A - that's some current! You may want to look into a solid state relay of sorts -- they have much lower 'on' resistance than conventional mechancal relays so won't get hot. They also don't arc so won't weld the contacts together when they are turned off (an inductive load - like an inverter - can do that easily to a conventional contact).

How about using an old starter relay, if you can't find anything else?

What are you trying to do? Put a dryer in your car like in "Pimp my Ride"? Whatever it is, it sounds cool!

Regards, Remcco

A good bet for the part you are looking for wold be at an RV store.

DO NOT use an automotive starter sel. as they are intended for intermittent use only. At a RV parts store you will find a relay that looks like a Ford type relay but designed for long term use. Cost about $15. As for fuse you might try out an auto reset breaker. Got a 50A unit several weeks ago for $3.25.

RV's can use a lot of power when on battery power and when looking for high current rated parts, RV parts house is a very good location to look for these kind of parts.

Mickey

Sure they do. You just have to buy DC output solid state relays. A Crydom D1D40 will switch 40 amperes DC. A little low for this application, and a little pricey at $71 and change, but they do exist.

Back under your bridge.

Yes, they do - an age and a half ago I got paid designing these things. You are probably thinking of a 'hockey puck' SSR - you are right in saying most of those are AC.

Regards, Remco

If the device even has a single junction device (2N3055) style it will have

0.7 volt drop, even more if it's totempole design. That might not look like much, but 0.7Volts at 80 Amps is quite a bit of dissapation.Considering this circuit can be carrying 12X80=960 Watts of power,ANY IR drop will be a problem. Go with the power relay, save a bunch of headaches. Your MAJOR concern is what to use for an alternator. Also..the regular car battery is 65Amp/hour rating at best. A deep cycle can be around 115A/H. Your going to need at least 200Amp rating to keep up. If your going to run a big heavy drill motor, no sweat...but something continous...no way.

A 2n3055 in a solid state relay? Wouldn't be better to use some sort of high power FET as is common practice in the industry? Their RSDon is very low (subOhm) and thus forward drop and power dissipation is low. You would need to slam them to saturation but that's not a huge problem.

But we're getting off topic here (it is "alt.auto.subaru" _not_ "alt.geeky.electronics.stuff" :) and we are probably boring he masses with electronic trivia so let's not go there again. I think Matt has enough suggestions to do what he needs to do - a mechanical relay is perfectly valid; we've been switching power this way for at least an age or so...

So, Matt, what are you switching? It sounds ambitious, having high power and thus being cool by definition. :)

Regards, Remco

It's an 800 watt inverter. I would never use that much power, but its there if I want it. When the inverter isn't drawing much power, the fan turns off and it goes into a kind of power saving mode. The thing is rarely used and I have a switch on the dash to turn it on. yes, I have run a drill in a place where there was no power, but only for a few minutes. This is for very intermittent use, but it is pretty cool!!

thanks for the help.

I am not clear as to why you need a relay. I have a 2000 watt inverter, hooked to an isolated battery, in my truck. Need to hook up 00 welding cable to power it. Just ran it though a 200 amp fusible link (from NAPA). When the inverter switch is off it draws no power so why do you need a relay?

I am assuming he want to make sure the inverter power is off when his car is off since he intends to run it off the main battery.

Regards, Remco

and also to have an on/off switch on the dash instead of using the one on the inverter. then putting the plug in a more accessible place.