Air Compressor Timer

[Beechwood Chip]

A while back I was lying in bed and I thought I heard an air compressor.  I figured it might be emergency street repairs and went back to sleep.  The next day I was closer to my shop and I heard my air compressor kick on.  I realized that I had left it on the day before.  Since it was at full pressure, it wasn't making any noise so I didn't realize it was still on.  Whenever the air pressure dropped it would kick on again.

So, I bought a timer switch and permanently attached it to the air compressor.  Now, whenever I need to use the compressor I turn it on for 15 minutes or one hour or whatever, and I don't need to remember to turn it off.

I did the same thing with my ancient George Foreman grill which has no switch or indicator lights.

[Von]

I had to go to the garage and take a photo. Exact same logic.

[fcschoenthal]

Those look like a great idea. Where did you guys get them?

[Beechwood Chip]

On 2/27/2025 at 8:49 AM, fcschoenthal said:

Those look like a great idea. Where did you guys get them?

Amazon

 

[Chestnut]

Interesting i just leave mine on all the time.... I guess that's one downside, upside?, of the california air tools that are super quiet.

[Tom King]

Great idea!   Do they come in 240V?

edited to add:  I looked but for what one costs to be big enough, I can burn a Lot of electricity when I forget.  At least it's far enough from the house that no one hears it but the horses and foxes.

[Beechwood Chip]

On 2/27/2025 at 9:27 AM, Tom King said:

Great idea!   Do they come in 240V?

Found this, 2HP @ 240V

[Tom King]

Not big enough.  Need one for 7-1/2hp single phase.  I downsized the motor with a smaller pulley on a 10hp 3-phase one. 

Thanks anyway,

[Beechwood Chip]

On 2/27/2025 at 9:42 AM, Tom King said:

Not big enough.  Need one for 7-1/2hp single phase.  I downsized the motor with a smaller pulley on a 10hp 3-phase one. 

Thanks anyway,

There are timer relays like this one, but you'd have to finagle the connections.  If you add the word "relay" into the search, you find stuff with higher amperages.

[Tom King]

Thanks for the effort, but my to-do list is already too long as it is.  I don't forget it that often enough to bother with the wiring changes that would be needed.  It's hard wired in.

[pkinneb]

So when I first read through this I thought well I leave mine on all the time and rarely hear it when I'm in the shop much less anywhere else (My shop is stand alone) However now I'm thinking I should get this for my little California AIr Tools compressor in the attached garage I use for my car lift. It sits on the other side of my office wall and if I forget to shut it off it's still loud enough it scares the crap out of me when it turns on LOL. Thanks for the info

[fcschoenthal]

I used to leave mine on all of the time. It would run probably a couple of times a day for less than a minute, so I didn't see any harm in it. My wife is enough of an alarm reminder that I've left it on, so I started shutting it off until I need it. Only takes a minute or two to get up to pressure, so not a big deal either way.

I was more interested in other uses for the timer. I can see using it for chargers or the occasional time my mini-split doesn't have quite enough oomph and I use a space heater for a little while.

[Von]

I have an attached garage shop and my compressor kicking on in the middle of the night was burning up my points with my sweetie.

[Tpt life]

I find it far more common to wire large compressors into a switched outlet, so that “turning the lights off” gets that switch also. 

[Coop]

That’s a neat deal. Being retired from the fire protection industry, I’d be more concerned with a fire than using electricity. However, my refrigerators and freezers run 24/7 but I guess they are suppose too. 

[Mark J]

I'm going to get two.  One for the compressor and a second for the cordless tool battery charger.

[Coop]

Two of you have mentioned getting one for the battery chargers. They couldn’t draw that much electricity. Is there another reason? 

[Beechwood Chip]

On 3/12/2025 at 5:21 PM, Coop said:

Two of you have mentioned getting one for the battery chargers. They couldn’t draw that much electricity. Is there another reason? 

Many "dumb" battery charger manuals say not to leave batteries in the charger once they are fully charged, or the batteries can catch fire or explode.  Rather than remembering to come back and pull the batteries (or unplug the charger), you can just start a timer when you put the batteries in to charge.

All of my chargers are "smart", except one.  I just leave that plugged in with the battery charging.  Hasn't caught fire yet, but that probably means I should go downstairs and unplug it now that I've jinxed it.

I think the warning is more of a "if the batteries catch fire, you can't sue us" type thing.  But I just saw a thing about house fire caused by charging electric scooters, saying not to charge them overnight, and to only charge them in a room with a closed door, not on your escape route.

[Mark J]

@Coop, back when we were young the common knowledge was that overcharging would harm batteries.  That truth has probably changed with time, but I "never grew up".  Even if it does no real harm, I figure I can plop a battery in the charger, punch the timer button, then come back for that battery, say three months later and not feel guilty that I forgot about it.  

[Coop]

Thanks guys. I was wondering if that was the concern. I need to make a battery charging station in the very near future and I guess I should do the same. Unfortunately we have my wife’s Ryobi toys and my DeWalt and Milwaukee tools so I guess better safe than sorry. 

[Beechwood Chip]

On 3/12/2025 at 8:29 PM, Coop said:

Unfortunately we have my wife’s Ryobi toys and my DeWalt and Milwaukee tools so I guess better safe than sorry. 

I don't have my DeWalt and Ryobi chargers on timers.  I'm careful to check the manuals and make sure that my chargers say that they can stay plugged in with batteries indefinitely.  The only chargers I worry about are 20 years old or off-brand.  My charging station doesn't use timers, and I wouldn't include one if I was building a new one.

[Coop]

I’ve had my DeWalt lunch box size and the slim one in chargers for a couple of years without a problem. However, a friend that is much smarter computer wise than me, saw them a while back and questioned why they were left unattended. My shop is detached so I may just spend the money on sandpaper and call my insurance company if there is a problem! 

[Beechwood Chip]

Hmmm, I asked ChatGPT, and it said that modern Li DeWalt and Ryobi chargers had protections to prevent over-charging, but leaving batteries in the trickle charger could reduce battery life.  It recommended taking the batteries out when charged, and not leaving batteries in the charger overnight.

It said that it was even more important not to leave non-Li batteries in the charger.

So, Maybe I'll add timers to my setup.

[Von]

Last time I dug into this I came to the conclusion there was no problem leaving my DeWalts in the charger (and I see the charger does shut down once they are charged) except, and sorry to add another wrinkle to this conversation, when it's below freezing:

https://www.dewalt.ca/why-dewalt/featured-articles/best-practices-for-battery-life