using relays for auto on solutions

Hey guys,

While I have a good amount of experience installing my car PC's for the last year or so, I'm just starting to learn about relays and how they work. Currently I am using a laptop with a power inverter which is wired to my car battery to power the laptop. I also use a carnetix power supply to provide 5v of power to my 8 port USB hub, as well as the 12v line to power my external HDD. The main line on the carnetix is broken for some reason, therefore it doesn't power my laptop.

The problem now, is that when I power on my car, I need to hit buttons to turn on the power inverter, as all as a button for the HDD, and finally flip the toggle switch from my laptop which I mounted in the arm rest.

I would like to use relays to turn all of this on when I turn the ignition on. I've enclosed a diagram (although a bit juvenile) of how I think it should work (from what little I understand of relays), but am still unsure of how to make the laptop turn on by itself. Can I use the IGN/ACC that runs through my car for that, or do I need to make use of the ACPI wire from the carnetix?

Is there a Year,Make,Model in there some where...? Do you have the ability to verify wires...(+,-)...Or will just the wiring of the relays be sufficient...? Can the inverter be on whenever the car is on...Im guessing what you mean is on the inverter...You have to hit the toggle switch to turn it on...Is this just a ON/OFF switch...Or is it a momentary switch...? Do you want the ability to turn these off / on while driving...Or is on when car starts...and then off when car is shut-off good enough...? And maybe elaborate a little on the switch for the HDD...Toggle,momentary...etc...How is it currently wired...?

-------------
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

If Howie says it, then so be it.

It reminds me of what was said Creating relays for auto on solutions 11:10 AM (26?Nov09).
Clever Dick.

eerily similar...

-------------
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

oldspark wrote:

---

If Howie says it, then so be it.

It reminds me of what was said Creating relays for auto on solutions 11:10 AM (26?Nov09).
Clever Dick.

---

We should give him thanks and praise... Almost God-like...

-------------
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

I agree!

He reminds me of an all seeing all knowing god....

His influence is so far & wide....

Thank you Howie for teaching us in your own image....

Now if we can finish our startingline, but hopefully questions will be asked if detail is required...

Oh OK then, 12volt constant at whatever amperage required to 30, ign or ACC trigger wire to 86, ground to 85 and output from 87 to BOTH units, a) we still don't know what car this is, b) I'm buggering off to watch telly, poster on security section Viper 5301 problems has really wized me off, family must have come from Norwich via Kentucky.

?
It wasn't mean as a request, just saying that on both sites, this question has been answered with one relay should do the job.

It is now back to the OP - accept, clarify, query or thank.
Lack of reply is often take as being the last option.

Tommy was being funny... yes, the post on the other site is eerily similar to this one.
Mind you, that jerk suggesting a single relay writes way too much. (Admittedly, he crash-courses relays, and proposes 2-3 solutions.)

And the rest IMO is in appreciation of Howie & his succinct reply.
However as Howie knows, I read what is stated, not what it seems or what is hidden.

But good, now Starter has an answer, so it's his call.

Sorry guys, with the holidays I haven't been around much to answer lately, but I appreciate the responses. I just started to read them over today.

To answer some of your questions though: It is a 2002 Jeep Liberty. I'm not sure what you mean by verifying the wires, but I know which wires and which at the moment. The inverter has an on/off switch, so I would like to keep that switch set in the on position at all times so that I can just leave it and forget it. The inverter is just there to power the laptop, but when I'm about to turn the jeep off I put it into hibernate, so it can't last a bit even if there is no power from the inverter while the vehicle is off.

I don't care if I have the ability to turn the inverter on/off while driving, just want to make sure that it turns on when I turn the ignition, and that there is no power draw when the engine is off.

In regards to the hard drive, it is tucked under the rear passenger seat, and requires 12v which comes from from Carnetix. There is also a USB B which runs to the external usb hub (5v, also powered by carnetix) then USB to the laptop. There is a toggle switch for either on/off. I would also like to make it so when the ignition is turned on, hard drive turns on, when ignition is off, hard drive powers down.

I'm sorry for the lack of details earlier, I should have been a bit more clear.

Also, I thought IGN/ACC were the same thing, that's why I had mentioned it before.

It is still the same solution.
One relay supplies +12V to the lot.

ACC is off during cranking/starting whereas IGN remains on.

Or better still, run the relay off the charge light circuit.
(Like a fuel pump or aux battery relay.)

But if you want it to stay on after an engine stall, it should control a latching relay (circuit) with a separate button to turn it off.

Can you throw me a link to what I'm looking for specifically, as far as a relay goes? Because I've found this: https://www.google.com/products?q=TRIAC

as well as this:

https://www.google.com/products?hl=en&client=firefox-a&rls=org.mozilla:en-US:official&hs=Azm&q=automotive+relay&um=1&ie=UTF-8&ei=up8SS4P5MtWYlAfO4IiMBA&sa=X&oi=product_result_group&ct=image&resnum=4&ved=0CC4QzAMwAw

so I'm not really sure what I am looking for.

See adding a second battery (page-3; 2nd reply) for info on an 80A latching relay.

Not that is what I had in mind....
The on-whilst-charging method I use is to connect a relay (solenoid) from the alternator's charge lamp circuit (commonly labeled D+ or L) to ground.
The relay the energises when the alternator is charging.
It's a common method of powering (electric!) Fuel Pump relays (so that fuel pumps turns off if the engine stalls).

However not all charging systems will handle the relay.
If you already have a similar relay (like an existing relay to power the fuel pump or other loads), then no problem - you trigger your new relay from that relay's switched output (rather than adding another solenoid to the charge lamp circuit).

Otherwise you could add some buffer to remove your power relay's solenoid load (typically 60 Ohm or about 200mA) so as to not load the charge lamp circuit (maybe an intermediate high impedance relay with 160 Ohm, 400 Ohm, or higher), or a transistor circuit etc).

Or you could control your relay from another circuit - typically the air-flap for EFI vehicles, or thru an ignition detection circuit which is ON whilst there is still spark (either method often being used as a backup for fuel pump relays).

Or there is the Oatley K227 "Dual Battery" kit that is also linked from the above "adding a second battery" to here.

The Oatley kit K227 (AUD$22.00) can duplicate the charge lamp circuit functionality wise - ie, its relay is ON when the vehicle is charging.
Although it switches 80A, in your case I'd just use it as the "charging signal" for your power relay.   

A disable switch is easily added, but the push-button "off" switch would still have to be pressed to open your relay (and kill power to your system).

Standby for a diagram of the latching relay system.....
(PM me if I forget.....)

I wouldn't worry about triacs or SCRs. Besides, they can be tricky to turn off in DC applications.

How's this as a systems diagram? (schematic etc)

It may have errors, and it isn't quite a wiring diagram though enough info should be presented for the semi-experienced.

And it has its own ramble....



PE: FIXED!!! If the filename is too long, images won't post & you get just the red square! #*^%&*!#!! Guess who uses descriptive filenames!