12v PCP pump power supply on the cheap cheap

[tag1000]

When I bought my GX-CS2 it didn't come with 120v -> 12v power supply so I've been using it at my Jeep to pump up my guns. I'm sharing this because I'm excited that I got this working. I'm IT guy and throw away server power supplies all the time, so I decided to keep a few for powering LED lighting in my house. They work great for that by the way. So I hooked up a large 66amp unit to the pump and it immediately shuts itself OFF, apparently it exceeded a amperage threshold it didn't like and turned OFF to protect itself. When you first turn the pump ON the inrush current is to high so I bought a 20 amp 2 Ohm Inrush Current Limiter and wired it in series from the positive side of the 12v server power supply to the pump. This causes the pump to start slower and then speeds up once the normal operating current passes through the ICL. Now I have a great high quality power supply for my pump. The server power supplies need to be jumpered on some pins to make them think they installed in a server and pinouts to do this are readily available if do a little Googling. Total out of pocket = $5.5 for the ICL

 

[qball]

Very cool! You might want to switch to lower end power supply because this power supplies sucks up power like no other. Maybe a descent workstation PS? Hard to beat the price though. 

 

[JimNM]

I have used computer PS for 15 years to power Nimh and Lipo battery chargers for my R/C airplanes. When you are feeding 5000 mah batteries at 28 volts, you need a PS with some cajones.

 

[qball]

That’s a lot of cajones!!! Even low end 800w PS running at 80% is 640 watts. GX compressors tops out at 250w hence the need to reduce the power with current limiter. Some of the PS I use in chassis are in the 2000-2500w range. I can get the old ones for free but powering them is a different story. LOL 



I say a descent quality 300-400w desktop PS might be perfect. 

 

[tag1000]

Everything is still working great. I did install a SPDT switch under the main GX breaker switch to flip between the ICL (series) and ICL (short) as i didn't

want all that heat and i just need it to start the pump and then short the ICL after 4 sec to bypass. 

I actually used the 77 amp unit (left) in this post, and I also setup a 60 amp (middle) and the far right is in progress and is the 66 amp newer unit and smaller. The smaller unit will be my "goto" unit for the GX pump.

 

[Chickenthief]

Dont cut the choke to close!!!

Most all switchmode supplies do not tend to like spikes in inrun current, in the almost shorted startup current of a standard DC motor. Run may be 5A but start up might be 5-10 times that (or more!).

So thinking that if you have a 250W compressor it will only "need" anything over 300W PSU is no good! The supply detects the current "overrun" and goes into safety mode ie, throttle down and the motor wont ever start up properly.

 

[tag1000]

thanks