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First attempt at a RC bot, PLEASE help! :-)

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jwatte:

--- Quote ---Also, any clue where one might get a big red emergency shutoff button that will not melt with 30A-60A running through it?
--- End quote ---

http://www.trossenrobotics.com/store/p/6362-Huge-Red-Panic-Fire-Button.aspx

This button does not do 60A; you'll need a relay for that. I *think* it's spdt, so you can wire it to break current; use one button to energize the relay coil; let the relay latch itself; use this button to break that latch.

Duane Degn:
The big red button jwatte linked to was the first button that came to my mind when you mentioned you wanted a big red button. I have a couple of those big red buttons and they are cool by they might be a bit too big for your application. The red dome is also prone to scratches so you'd want to be careful how you used it.

I do think it's one of those parts just crying out to be used.

Have you seen MPJA's buttons?

http://www.mpja.com/Push-Button-Switches/products/63/

I think they have some fun buttons and pretty reasonably priced.

I'm looking forward to your future progress on this robot.

ROBOT420:
Thanks for the links and info fellas! Thant BIG red button is a bit big for the space still available in my design, but, IT IS pretty damn cool so I will use on on something at some point.
Here is a diagram of the run/charge circuit on my bot. Right now I manually disconnecting the ground wire from the battery to the motor controller to turn it off when not in use. To charge, I unplug both quick connects going from the battery's to the motor controller and plug them in to the charger's quick connects.

http://s1362.photobucket.com/user/420photo420/media/20130502_103217_zps0add7ea2.jpg.html?sort=3&o=0

Where can I find a 60A DPDT (a DPDT is what I need for this correct? :-[)switch that I could wire all 6 leads (+&- from 24V battery pack, +&- from the 24V charger, +&- from the motor controller) to, and simply switch between "Run" and "Charge" mode? If we can figure this out it would double as an "off" switch by just switching it to charge mode weather the charger is plugged in or not. Thanks again for all the help! ;D Steve

jwatte:
You actually only need a SPDT, as you can keep the grounds connected at all times (charger, battery, and bot, can all share a ground.)
Breaking the ground may be advantageous in some cases (if you get ground loops, say,) and may actually be a disadvantage at other times (if you use a big fuse, you may lose that protection, for example.)
60A is a lot. You need a "contactor" instead of a "relay" at that point. However, are you really drawing 60A continuous? If the 60A number is just transient spikes, and average draw is, say, 20A, then a 30A relay will serve you just as well.

You can also build a 60A breaker using a P-channel MOSFET. It might actually be cheaper than going with contactors. Just beware to specify the P-channels based on your highest load-dump voltage -- for a 24V system, 60V minimum, and ideally higher than that. (A TVS across it might help protect it, too.)

SPST isn't so bad, though. Keeping the charging port connected to the battery at all times is convenient when you have the bot on blocks and are testing.

Here are some parts from Digi-key you might want to look at:
http://www.digikey.com/product-detail/en/1393276-7/PB1319-ND/3318138
http://www.digikey.com/product-detail/en/ADQM16024/255-2597-ND/2125665
http://www.digikey.com/product-detail/en/LEV100A5ANG/A101164-ND/2362833

Note the lack of insulation on the first (cheap) part! Also note that it's just barely within your specification. I'd go with the second.

Or, if you want MOSFETs: http://www.digikey.com/product-detail/en/IXTP96P085T/IXTP96P085T-ND/1995412
Just make sure to have a sufficient heat sink! (I might also put two in parallel, just to make sure there's sufficient overkill.)

Duane Degn:
Those relays sure seem expensive.

I think this one would work just fine. Edit: As long as it meets your current requirements.

https://www.sparkfun.com/products/10924

Since the current rating is when used with 220VAC I believe it could take even more current at lower voltages (I'm not at all sure about this). I've used them to control kitchen ovens.

I believe the above relay has a 5V coil (which you'll likely have handy). You don't wont to power the relay directly from a microcontroller pin. You'll want to use a transistor to power the relay. Never mind. You want to control the relay with a button.

Here's a similar relay with a 12V coil.

http://www.mpja.com/12VDC-SPST-NO-30A-Omron-Relay/productinfo/19059%20RL/

I'm confused why it's rated at 30A @ 250VAC but only at 15A @ 125VAC. Does that mean it would be only good for 3A @ 25VAC? I'd think it would be the other way around with the relay being able to handle higher currents at lower voltages?

MJPA has lots of other relays as well.

http://www.mpja.com/Mechanical-Relays/products/134/

Solid state relays tend to last longer than mechanical relays in my experience. I doubt you'd need one but MPJA also has some SSR.

http://www.mpja.com/Solid-State-Relays/products/133/

Be aware with SSR, you need to make sure you get the right kind for your needs. AC and DC SSR are not interchangeable.

Edit: I had lots of bad advice in this post. Make sure and read jwatte's post below.

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