David Sparkes Posted December 31, 2014 Share Posted December 31, 2014 I suspect more than a couple of people on here have the PM982 from Paddock Spares. Has anyone seen quoted, or measured, the current consumption please? Since Santa grabbed my card in December, one appeared in my workshop. In contrast to the standard design, I'd prefer a long electrical lead, and a short air hose, but I want to have an idea of the section size of the cable I should be looking for. Thanks. Quote Link to comment Share on other sites More sharing options...
jackmac Posted December 31, 2014 Share Posted December 31, 2014 Just got mine today! 99% sure it says on the box 45A max. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 31, 2014 Share Posted December 31, 2014 If you want a long lead, make it fatter again.... otherwise volts drop will kill the amount of power you get to the compressor. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted January 1, 2015 Share Posted January 1, 2015 45 amps, wow! Guess it's not a cigarette lighter job then Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted January 1, 2015 Author Share Posted January 1, 2015 Just got mine today! 99% sure it says on the box 45A max. Thankyou for prompting a second check, the box is silent on the matter, but the instruction leaflet does indeed say 45 amps!! If you want a long lead, make it fatter again.... otherwise volts drop will kill the amount of power you get to the compressor. That is why I was asking, to base the lead specification on the current and voltage, not on the short lead fitted already. Regards. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted January 1, 2015 Share Posted January 1, 2015 The 45 amps will only be when at maximum pressure, or possibly even just when trying to start when already at maximum pressure. I have one of those compressors and it is a little annoying that the pressure guage is about as far away from the switch as it could be! Quote Link to comment Share on other sites More sharing options...
jackmac Posted January 1, 2015 Share Posted January 1, 2015 What does the push button on the switch box do? Seemingly nothing as far as I can tell? Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted January 1, 2015 Share Posted January 1, 2015 I'd imagine it is some sort of overload protection reset thing Quote Link to comment Share on other sites More sharing options...
Escape Posted January 2, 2015 Share Posted January 2, 2015 What does the push button on the switch box do? Seemingly nothing as far as I can tell? The switch box has a resetable fuse, with the button you can reset it, but only after it has been tripped. I agree completely that is quite annoying to have the switch so far from the pressure gauge. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted January 2, 2015 Author Share Posted January 2, 2015 Well, some may recall a curse of allegedly Chinese origin, 'May you live in interesting times'. I have some interesting findings. After completing the essential task (getting a 2.25 diesel to start after de-waxing the fuel supply) I decided I needed to investigate. Are we going to quibble over an amp or two? I hope not, but if so, someone else will have to break out more sophisticated gear than I have. I used a clamp meter to measure the current draw of the compressor, on the 200A range (the other range is 400A). I didn't use the Peak Hold facility. I used a digital multimeter to monitor the battery voltage, and a second small clamp meter to monitor the alternator output current. I didn't measure time, nor the ambient temperature, nor the compressor temperature. The test was conducted outside in cold and windy conditions. The vehicle battery was fully charged, engine rpm varied between idle and 'maximum alternator output'. The test pressure vessel was a 7.50x16 tyre, the target was to run from flat to the 'maximum load pressure' on the sidewall, 85 psi, monitoring how the current draw changed with the increasing pressure. Free running, on an open pipe, the curly one, with the gauge and valve connector, the current drawn was 42 amps. Yes, it surprised me. I even checked that air was issuing from the pipe, it was. I connected the pipe to the tyre valve, and on starting the current draw was 45 amps. If I increased engine speed to 'maximum alternator output' (18 amps) the battery voltage rose from 12.1 to 12.7-ish, and current draw hit a high of 46 amps. This minor change was consistent throughout the test. At 65 psi the compressor cut out. The reset button protrudes twice as much as it normally does. Resetting immediately got about another minute of running, before it cut out again. I left the compressor to cool slightly, perhaps 5 minutes, before restarting. When it cut out again the tyre pressure was 75 psi, and I concluded the test. The motor section of the compressor did not give off 'obvious' radiated heat; the cylinders were 'warm', but as said, I did not actually measure temperatures. Conclusions: Any replacement lead needs to be rated to carry at least 45 amps all the time I now realise I forgot to monitor the supplied lead for heating. Nor did I attempt to measure voltage drop between the battery and the compressor. I don't think the compressor was running for 30 minutes, and I'm disappointed the tyre didn't reach full pressure before the compressor cut out. Reflecting on that point, I suppose the test had become artificial. The expectation had been that current demand would increase as the pressure grew, but this wasn't the case. In reality I don't think I'd ever need 85 psi in a tyre, so it would have been more realistic to inflate two tyres to say 45 psi. Something for others to build on. I may look at any lead temperature change, and volt drop, (two ways of seeing the same effect), but I'll wait for a day when the wind chill isn't attempting to remove all feeling from my fingers. I am glad to see it isn't just me that thinks "it is a little annoying that the pressure gauge is about as far away from the switch as it could be!", and "that is quite annoying to have the switch so far from the pressure gauge." Thanks for that. Regards. 1 Quote Link to comment Share on other sites More sharing options...
jackmac Posted January 2, 2015 Share Posted January 2, 2015 So much for the quoted 150PSI max pressure then! Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted January 2, 2015 Share Posted January 2, 2015 Cheers for the testing David, I must say I'm very surprised that a) the initial current is 45A and b) the current changes so little with pressure. I now wonder if the resettable fuse is in fact a little low! Maybe we would see a peak presure of 150 psi but they have chosen a fuse/trip rating that is very conservative to save warranty issues and it results in cutting out before max pressure due to increased current demands? Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted January 2, 2015 Share Posted January 2, 2015 Maybe it can get to 150 psi in a bike sized tyre before cutting out. Maybe the pipework or some of the valves / pump design are very restrictive accounting for the high No load current with little variation over the run Quote Link to comment Share on other sites More sharing options...
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