Time Delay Relay

[glenyoshida]

I have several items (freezer, laptop, electric blanket etc.) that I like to keep on when the engine is not running. I have a good ole manual rocker switch on them right now. I'd like to be able to run some of the equipment for up to 8 hours but don't want to forget one day and leave them on draining my 2nd battery. Although it's a yellow top I'd still rather not prematurely shorten it's life by draining it dead. I can build a Time Delay relay with a simple Capacitor, Relay circuit or something simple like this solid state circuit

http://www.aaroncake.net/circuits/relaytim.gif

But I'd rather just buy something already done. Time is precious and I've still got my CO2 setup to mount, tire carrier to build, etc. Yah know how the list never get's shorter just more expensive ;)

Anyone know of a 12v Time delay relay circuit already made that will work 8 hours then cut the power off? If it handles 5amps that's probably fine but I'd rather it be able to handle 10amps.

Or maybe a totally different suggestion to prevent the battery from being drained dead?

[arjan]

Omron has them, this one for example: http://www.ia.omron.com/product/family/195/index_spc.html
ABB will have them too. Just search for off-delay timers and make sure they have a 12VDC model. The one above is a bit bulky, but has a 12V version.

This is a nicer, smaller version from Omron, also available in 12V:
http://www.ia.omron.com/product/family/200/index_spc.html

[glenyoshida]

Freakin' Awesome! How did you know where to get one?

I just ordered the H3DE-M2. $60 shipped but this is a classic example of how paying the cash instead of making one saves lots of money the long run.
http://rocky.digikey.com/weblib/Omron/Web%20Photo/H3DE-M2%20AC%5EDC%2024-230.jpg

Thanks! For helping me out and posting up. I really appreciate it!

[arjan]

I worked for an electric supplier in the automation department. It's quite common stuff really.

They also have little Zen plc's in the $100 range. You can program them to do whatever you want.
For example you could use it to switch an electric locking diff like the stock toyota unit does. Or you can use it to control the back window for the 4Runner.
A winch with overcurrent protection or low voltage protection would be another option.
It's really all quite easy nowadays imo. Then I again, I build & design control panels and program PLC equipment for a living.

Hope it all works out for you.

Arjan

[glenyoshida]

I'm so glad. I was spending a lot of time trying to find one thinking to myself that someone has to make one. I actually spent hours looking for something a few times before and just kept giving up in frustration. So while easy to you it's a small miracle to me. :)

PLC. Now that sounds like a fun job to be. Do you have any robotics projects in the works?