Life at the end of the road

March 8, 2016

The ‘Murphy ASM170’ :-(

Filed under: daily doings, life off grid — Tags: , , , — lifeattheendoftheroad @ 10:05 pm

Sorry peeps but this is gonna be ‘dull as dishwater’ and I’m only scribbling it down in case I have to refer back to this in future. Today I spent pretty much the entire day wiring up a ‘generator start module’ for the neighbours they’ve got guests in for Easter and being able to automatically start the generator is kinda essential. The neighbours themselves have managed just fine on wind and solar from the Proven WT2500 and 1kW of solar but extra bodies means extra demands on the system so fitting this was crucial. The old Trace SW4548e inverter that served me well for years has inbuilt relays for generator starting but Trace were unique in that respect. All the other ‘off grid’ inverter chargers on the market require a separate control module (unless the generator has one built in) to operate the starter, fuel solenoid and any shutdowns.

The Trace died last year and whilst I did manage to repair it, it failed again 3 months later Sad smile One of these  was purchased as a replacement, for a fraction of the cost of a quality European/American one. That failed 3 months later too but was repaired (eventually) under warranty. Having said that for the price I was well impressed, I wouldn’t buy one myself as it’s ‘transformerless’ so not capable of ‘AC coupling’, however for anyone ‘off grid’ and ‘on a budget’ it’s worth considering. They’re built in Taiwan and go by several names ‘MPP Solar’, ‘OPTI’ and ‘Voltacon’ are just a few but if you do buy one then I’d at least source it from a dealer in your own country, return shipping to Taipei is not cheap.

Like most ‘off grid’ inverters these days the have in inbuilt ‘volt free’ switch that operates when the batteries get low or demand is high. The Murphy or any other suitable ‘start module’ uses these contacts to ‘auto start’ a suitable generator. The Murphy ASM170 was recommended to me by a friend and it’s what I fitted at Sonas but there are others that are available, some for a fraction of the cost off eBlag. However, beware of cheap ones that rely on ‘timed cranking’ that can leave the starter motor engaged for a short while after starting. The likes of the Murphy and DSE units have frequency sensors that stop the starter motor as soon as the generator produces 50Hz (60Hz in the US).

If you don’t have ‘a memory like a hen’ and are capable of reading instructions I guess you could fit one in two or three hours, it took me all day, despite having done one before.

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Most of these modules are ‘pilot only’ insomuch as they provide a signal for the various functions but need an external relay. The Lister already had two in that silver box that I’d fitted years ago that were controlled by the Trace . They needed a little re configuring but made the job a lot easier than it could have been. The wiring is actually the easy part, the hard bit is setting the ‘DIP switches’ and adjusting the potentiometers to get the right number of cranks for the starter and setting the frequency to disconnect the starter. At least that’s what I find difficult, having the concentration of a gnat and not being able to remember how I’d done mine!


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The wires are clearly labelled but the loom they’re in and the plug to connect it to the controller are an ‘optional extra’!! Quite how you are supposed to fit this unit without them is beyond me but buying it will set you back another £36 even more if you forget to order it with the unit and have to pay double the delivery!!

Anyway, eventually I got it starting in the ‘Manual’ position, running two wires to the NO contact on the Voltacon (one connected to the ASM170 and one to the battery) should then have provided starting in ‘Auto’. Sure enough I went into the kitchen and turned on the grill and oven.

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Drawing 4.23kW from the batteries soon dropped the voltage and after about 5 minutes the generator started just like it should have done. I was ‘well chuffed’ so called it a day, it was well after 17:00, the wife was home and I had to make dinner Smile

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