high current parts

[Matt]

I'm trying to properly install a high current device. Its an AC inverter
that can require up to 80A at 12v. I ran some 6ga wire to power it and I'm
trying to find some parts to finish the job. Where can I find an 80A relay
and an 80A fuse? Also I need the connectors attach the wire to the battery
and the relay. I checked Advance Auto parts but they only had up to 30A
relays but they had 80A fuses. Does anyone know if a chain store would
carry this or know a local place around the northern Virginia area? if not,
does anyone know an online dealer that supplies this kind of stuff?

Thanks!

 

[CompUser]

I'm trying to properly install a high current device. Its an AC inverter
that can require up to 80A at 12v. I ran some 6ga wire to power it and I'm
trying to find some parts to finish the job. Where can I find an 80A relay
and an 80A fuse? Also I need the connectors attach the wire to the battery
and the relay. I checked Advance Auto parts but they only had up to 30A
relays but they had 80A fuses. Does anyone know if a chain store would
carry this or know a local place around the northern Virginia area? if not,
does anyone know an online dealer that supplies this kind of stuff?

Google up Digikey, Mouser or Newark electronics.

 

[Dr. Rastis Fafoofnik]

I'm trying to properly install a high current device. Its an AC inverter
that can require up to 80A at 12v. I ran some 6ga wire to power it and I'm
trying to find some parts to finish the job. Where can I find an 80A relay
and an 80A fuse? Also I need the connectors attach the wire to the battery
and the relay. I checked Advance Auto parts but they only had up to 30A
relays but they had 80A fuses. Does anyone know if a chain store would
carry this or know a local place around the northern Virginia area? if not,
does anyone know an online dealer that supplies this kind of stuff?

Thanks!

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.

 

[remcow]

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

 

[Mickey]

I'm trying to properly install a high current device. Its an AC inverter
that can require up to 80A at 12v. I ran some 6ga wire to power it and I'm
trying to find some parts to finish the job. Where can I find an 80A relay
and an 80A fuse? Also I need the connectors attach the wire to the battery
and the relay. I checked Advance Auto parts but they only had up to 30A
relays but they had 80A fuses. Does anyone know if a chain store would
carry this or know a local place around the northern Virginia area? if not,
does anyone know an online dealer that supplies this kind of stuff?

Thanks!

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

 

[Dr. Rastis Fafoofnik]

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).
Solid State relays DO NOT work on DC Circuits.....

 

[Jim Stewart]

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.

 

[remcow]

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

 

[Dr. Rastis Fafoofnik]

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.

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.

 

[remcow]

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

 

[Matt]

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.

 

[calhoun]

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?

 

[remcow]

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

 

[Matt]

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.