Author Topic: Portable HPA compressors  (Read 469 times)

Alan

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Portable HPA compressors
« on: July 02, 2018, 07:15:23 AM »
There is a new class of HPA compressors hitting the market—Portables. The latest offering is coming from Benjamin, and called the Traveler™ (https://hardairmagazine.com/reviews/using-the-benjamin-traveler-portable-hpa-compressor-part-one/). Like its stablemates, it is powered by a nominal 12 volts (think car battery), but does come with an AC to DC power supply for home use. Their usability isn’t in question per se, but powering them is!

At present, none of the suppliers has an on-line manual. About all they say is how long it takes to refill a PCP under specified conditions. Unfortunately, there are several issues which seemingly are being ignored, but should be addressed. Allow me to digress.

In another life as-it-were, I’ve been an amateur radio operate for nearly 50 years. Operating from one’s vehicle has always been a love of mine. In fact, my “other” web site is dedicated to that very facet of amateur radio (http://www.k0bg.com). The peer-reviewed information presented comes not just from my personal experiences, but from noted sources as well. Cutting to the chase, I do know a lot about powering high-average loads from automotive, lead-acid batteries. And this is where the rubber meets the road, pun intended!

All modern vehicles have battery monitoring systems (BMS). They all incorporate a Hall Device to measure loads to and from the battery. The devices are typically mounted around the battery’s negative lead, or build into the negative connector. They use this “coulomb-counting” to determine the SoC (state of charge) of the battery. The SoC is important, especially so when the vehicle in question has EIS (engine idle shutdown) as mandated by the fed. Suffice to say, one does not want to bypass the BMS, least you find yourself dead in the middle of rush-hour traffic!

The lack of on-line technical information is bad enough, but not knowing what the manufacturers and/or retailers suggest with respect to powering these compressors, leaves a lot to be desired! But few suggestions can be made regardless.

These compressors draw about 30 amps at a nominal 12 volts DC. Depending on the age, size, and SoC of a lead acid battery, will roughly determine how much its voltage will be effected. This is important to know; Drawing down the voltage of a lead acid battery below 10.5 volts UNDER LOAD, will reduce its CCL (charge cycle life), sometimes drastically. It is for this reason I question Benjamin’s on-line comment: Fills a Armada/Marauder 0-3000psi in 8 mins via Riding Lawn Mower battery. I can't speak for your lawnmower, by my electric start, riding mower would be hard pressed to even start the compressor! This brings us to the crux of the matter—how do we prevent causing issues when powering these devices from our automobile?

First, it is imperative that the BMS not be bypassed. The easiest way to prevent this is, to connect the compressor's negative lead to a hard point on the chassis close to the battery's negative lead connection point. The battery's positive connection is okay to use.

Secondly, ALWAYS have the engine running BEFORE switching on the compressor. Remember, it is the alternator, not the battery, which should supply the requisite energy to power the compressor.

Failure to follow BOTH of these suggestions could easily leave you out in the field with predicable issues!


  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

Briar Patch

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Re: Portable HPA compressors
« Reply #1 on: July 02, 2018, 08:24:04 AM »
    I think things like this happen more and more frequently, at least it seems to at my place of employment.
An idea for a product or an improvement will be developed and implemented without enough input from those who have significant amounts of practical experience with the equipment involved.

In the cases I usually see it is younger engineers who come up with the ideas or products.  They are plenty sharp and some of the things they come up with are ingenious.  Sometimes there are just factors they may not be aware of that impact the effectiveness of their ideas.

The good news is that things eventually get worked out. Something will get modified, or it will be scrapped. Unfortunately, there has been time and money invested that could have been avoided if folks with more experience had been consulted.

I do like the idea of an ultra portable compressor.

BTW - I am not knocking engineers. The majority of them are a helluva lot more knowledgeable than I am.
  • Payson, UT

Alan

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Re: Portable HPA compressors
« Reply #2 on: July 17, 2018, 09:31:44 AM »
As an update, interested parties should read the second part of Hard Air Magazine's report on the Benjamin Traveler compressor.

https://hardairmagazine.com/reviews/using-the-benjamin-traveler-compressor-part-2/

Air Venturi has a similar compressor coming soon. I trust they'll read the article as well.
« Last Edit: July 17, 2018, 02:45:49 PM by Alan »
  • Roswell, New Mexico
Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.