Supplemental Electric Air Compressor

[Valence]

I remounted the Pioneer Tool Rack and one of the new air filters. It's a tighter fit than expected to get the shovel out, so a little bit of care is needed but it is still readily doable.



Before finalizing the wiring to the compressors, I'm actually finally going to mount the two 24" Ibis Tek light bars I bought years ago. Most of those specific updates will be placed in my Ibis Tek light bar thread.

One will mount below the bed in front of these air compressors, and the other will be on the opposite side above the fuel tank. From my test fits, I believe it won't add much to the finagling of getting the shovel out, which probably won't happen much anyway. I hope the light bar will actually help shield the air compressors from additional dust. It probably won't be much, but some would be a decent trade for the slightly added servicing difficulty.

The light bar will actually be mounted closer to flush with the bottom of the bed, but it's a bit challenging to hold both the 8lb light bar in place and take a picture.

 

[Valence]

A couple weeks ago when I was installing the filter on the second air compressor, I noticed what looked much like numerous internal cracks:



So I sent an email to Extreme Outback Products with the above pictures, expressing my concerns:

"...inside the air compressors it appears that the internal housings are cracked? Please see the attached pictures. Is this normal/expected? Or only a result of handling or other abuse? Do you have any idea of the run-time life expectancy remaining, if any?"
​

And I received the following reply:

"Those aren't cracks, no concerns run the compressors. I've seen this before, it is more of a casting flash. I would think you should be able to get at least 1000 hours between rebuilds. Just keep the filters oiled with Uni Filter oil and you're good to go."
​

Needless to say, I'm quite pleased by the reassuring reply. I'm also very happy I installed an hour meter so I can keep track of how much run time they see!


I have finished the wiring and 24V DC sub panel. I ran the power in front of the bed, secured via clamp/hangers:

 

[Valence]

I have test run the air compressors and relay power and they seem to work beautifully!

https://youtu.be/WemTCVYnsuM

However, as seen in the video, I've had some trouble with the little Pololu board listed earlier performing as I had hoped. On the product website there was a note about product limitations:

"Switch can lose its state when power is disconnected (the switch typically defaults to being off when power is first applied, but it can default to being on near the upper end of the operating range)"
​

I wanted the switch to lose state when the power was disconnected and didn't have any desires for it to remember. Yet, I have seen it default to both power ON and power OFF when the Accessory Switch first applies power. Also, as seen in the video above, it didn't always turn off, but sometimes it did. It is suppose to have a power operating range of 0-40 VDC. The truck is 24-28 VDC, which I didn't expect that to be too high.

I was greatly disappointed so I have replaced the switch with (what I probably should have used in the first place), an Alpine Tech On/Off selector switch. I could have used the original On/Off switch that came with the unit, but it was much more physically bulky.



Alpinetech CS-22 Black 22mm Maintained Selector Switch 1NO 1NC 2 Positions
https://www.amazon.com/gp/product/B00FLZ7E4E/


Legend Plate "OFF ON" with Holder, For Use with 22mm Switches
https://www.amazon.com/gp/product/B00ID4G7XY/

 

[Valence]

Update:

So as I've been driving the truck with the electrical air compressors, sometimes there would be a belt squeal, which would stop when I turned the switch for the air compressors to "Off". I have a 12V alternator above the stock alternator, which required one of the belts to be longer to drive the 12V alternator.



As can be seen, the longer belt doesn't provide much engagement, or pulley wrap, on the 24V alternator, effectively only driving the 24V alternator with a single belt. Both of the belts were tight. Therefore, I've determined that at full, or near full, load the 24V alternator requires both belts to not induce more drag than a single v-belt can handle without undo tension also putting more force/wear on all other bearings/pulley components.

I removed the 12V alternator (and all associated components) and went back to the stock setup. I put on two new belts (Gates #9465). The belts are a bit of work to get on as the bottom alternator bolts are hard to get to and I had to fully remove two of the three mounting bolts to get enough movement. This belt is the exact width for the pulleys and length in that I can get it on without removing the radiator and fan, but short enough that I can properly tension it with the limited alternator travel.

As can be seen during installation, the belts were not sequential but seemed to tighten up about the same. I don't think it'll be any problem.



Finished:



I drove the truck 37.2 miles with an engine run time of about 1.1 hours. Travel involved surface streets, residential, highway, interstate, and parking-lot low-speed maneuvering. I did not hear any belt slippage. I call that a success!

 

[Jbulach]

Other than the few bugs, how are the compressors working out, are you happy with their performance? What would you estimate their typical run time is when they cycle on?
Keep up the great work and informative threads!

 

[gimpyrobb]

Would an idler pulley help put more belt on the 24v alt with the 12v alt installed?

 

[rustystud]

Would an idler pulley help put more belt on the 24v alt with the 12v alt installed?

Yes it would, but the logistics of installing an "idler" pulley would be high.

 

[Valence]

Other than the few bugs, how are the compressors working out, are you happy with their performance? What would you estimate their typical run time is when they cycle on?
Keep up the great work and informative threads!

Thanks Mr. Jbulach! My apologies for the delay in getting back to you. I just spent 2-days in mistaken site ban purgatory (I thought the site was down, lol! It's all good now).

I am very happy with the electrical air compressor's performance! I'm starting to get used to their additional noise/vibration as they are powerful units. The truck's air tanks fill up quickly. The difference is quite noticeable, so much so that I basically run around at full air pressure all the time. With the electric air pressure switch I used, the engine compressor can cycle on to top off the tanks without the electrical ones coming on. The electric compressors run for less than 1 minute after starting the truck with empty air tanks. When the electrical compressors turn on due to air use by the air-assist steering, they're on for about 20 seconds or less.

I will note that there may be something wrong with my hour meter, as it's not quite to 0.2 hours run time yet, and it started at 0.1 when I purchased it. But I'm going to wait a bit longer and see as each 0.1 increment does mean 6 minutes of run time...

Would an idler pulley help put more belt on the 24v alt with the 12v alt installed?

Yes it would, but the logistics of installing an "idler" pulley would be high.

I'm going to have to defer to both of your expertise on that matter. I personally wouldn't even consider adding an idler pulley. If it'd fit properly, I'd be much more likely to replace the 24V alternator with a dual 12/24V unit. I never liked how that 12V alternator fit anyway.