This is probably a stupid question, but can you hook two big muffin fans up to the same spike?
Well if by hook up, you mean wire, yes I you can wire 2 muffin fans to the power side of the speed controller.
This is not a stupid question. As it turns out, the manual doesn’t say anything about connecting fans to Spikes. The power distribution diagram shows them connected directly to the breaker panel. As such, I suspect that you can connect them to Spikes, but I would only recommend it if you’re wanting to turn the fans on and off in software, and only if your load isn’t going to come anywhere close to 20A (which would take a lot of fans to do).
If your intent is to cool a motor or speed controller I would connect it directly to the breaker panel. This way if the robot is “disabled” but still has power the components will still remain cooled.
Mike, while I agree that keeping motors cooled is important, I believe the direct wiring of fans is not allowed. I believe that fans, non-functional decorations, and the like are all required to be on a spike.
We directly ran a fan (without a spike) back in 2003 to help cool our motors. The inspectors noticed it right away, as the fan was spinning away anytime the robot was turned on, and on the field… We were told to correctly wire before our next match.
Unfortunately, the 2007 manual does a very poor job addressing muffin fans. The power distribution diagram seems to show them not needing a Spike. The Robot section of the manual only specifies what gauge electrical wire to use with them. Based on the power distribution diagram I would say FIRST is allowing the direct connection to the breaker panel.
As far as your bad experience in 2003… If the muffin fans on the Victors are directly connected to the breaker panel I don’t see why other muffin fans shouldn’t be. It’s unfortunate not every regional can have a lead inspector who’s a FIRST veteran and also an electrical engineer.
My question is probably stupid, but out of curiosity. Why the heck do they call the small fans Muffin Fans? I think it’s a strange name. But I think that you should be able to connect the fans directly to a breaker since we do that with the fans on the Victors. However, it might be illegal to connect two fans to one Spike. Even though the current draw is no where close to burning out the Spike, rule R90 might keep you from doing this. It depends on what FIRST considers the fans to be.
<R98> Relay modules must be protected with a 20A circuit breaker. Multiple devices may be
connected to relay modules if desired (but only one motor may be connected to each relay
I consider Muffin Fans to be part of the “Multiple devices”, but you would have to contact FIRST about their interpretation.
In the past, fans were allowed (and expected) to be connected directly to a 20 circuit breaker. I am surprised that an inspector required a Spike for this purpose. The rules specify which loads a Spike may control.
The fans in this size origianally were small and looked like they were made from muffin tins. (unpainted aluminum rotors and housings look just like aluminum cup cake or muffin tins.) It has become common usage for all small, square fans to be called 'muffin" but each manufacturer uses a different term in referring to fans of this type in different sizes.
Be aware that the Chalupa motors (both large and small) are closed devices and blowing cool air over the surface does little to cool the inside. The only conduction to the armature is through the end plates and shaft. The same can be said for virtually all motors in our kit even if they have openings in the case. If your motors are running hot in a two minute match, you should reconsider your design calculations. If they are running hot during long practice sessions, then do whatever you can to keep them cool so you don’t have to replace them. Burnt motors stink forever.
BTW, remember you can’t modify the motors in any way other than to facilitate mounting or shaft mods. See the robot rules. I know what you are thinking and drilling holes in the Chalupas is illegal and reduces the output power of the motor as it reduces the magnetic field.
I have been reading through the threads about the muffin fans, but I still can’t figure out the best way to connect the large muffin fans. I f anybody can help, it would be appreciated.
Yeah, we hooked our fans together on the same power sources, but it wasn’t a spike relay, it won’t have that much outcome on the plays anyway
You may connect your fans to a 20 amp circuit breaker on one of the small fuse blocks. You didn’t specify how many fans you plan to use, but two are acceptable on a 20 amp breaker. Were you planning on more?
we will probably use two thanks for the help.