Electric Dreams

Ever since my first car (1980 model Subaru) performing electrical repairs or adding electrical components has been an on going event.  If you had asked me when I was 20 years old how good are you at performing these repairs I would have replied (as arrogantly as a 20 year old could) “As good as a trained expert”.  Many years on and hopefully a lot wiser I now realize that I was a first grade novice with electrics back in my late teens and probably should never have been allowed to attempt any such repair or modification.  Sure I was able to wire up a CB or even fit a set of air horns (ah the good old days) well enough to get them working initially but chances are every couple of moths I would have to be doing repairs because they had stopped working.      

Back in those days I probably judged my ability to be able to do a job by the speed that it was completed.  Of course this was at the expense of quality workmanship.  Even basic things such as soldering wires together were unheard of for me.  Just strip the wire back, wind it onto your appliance then cover it with insulation tape.  Worked great until you went over the first corrugated track and the wires would rattle apart, or they’d get wet causing corrosion which would prevent a good connection.

Now days, even though I am much wiser (purely from learning by my many mistakes) I still consider myself a novice but I think I have progressed from just trying to get my accessories working to actually having them perform at their optimum capacity.  Sounds funny doesn’t it “working at optimum capacity”.  You’d think just because your accessory lights up, runs etc that it is performing at optimum.  In fact nothing could be further from the truth.

Let me give this example.  I run a Hurricane air compressor in my car that I have been increasingly disappointed with since its purchase.  It works great for the first tyre, usually inflating it from 15 to 30 psi in around 3 mins or less but there after it would slow down considerably to the point that the final tyre could take as long as 5 mins to inflate over the same pressure range.  Of course my conclusion had always been, useless piece of cr%$#@ why didn’t I go and get the ARB compressor.

Until recently I had not considered that it was my electrical workmanship that was causing the problem.  The first indication I had that this may have been an issue was at Christmas of this year down at Denmark when after driving on the beach and trying to reinflate my tyres the compressor stopped working completely during inflation of the third tyre.  With my tail between my legs I had to go and borrow someone else’s compressor to finish the job off (Thanks John Mc).  After calming down and trying to find the problem I noticed that the fuse holder had melted.  Despite being a supposed heavy duty fuse holder (one of the black screw together in line types) it was not able to handle the current running through it caused by the power hungry compressor.

I replaced this with a more modern fuse holder that took blade type fuses (to match the fuses in the car) and spent the extra 50 cents to get a waterproof version.  This got me thinking about the compressor’s overall performance so one day in the comfort of my own garage I deflated my tyres and did a few checks on some of the electrical components.  My compressor is mounted under the driver’s seat so a fairly long wire is needed to get the power from the battery.

What I found may not surprise some but it blew me away.  I thought I had done a really good job when installing this compressor in the Paj 3 years ago (after all my mistakes as a teenager) but as I now know it was far from even adequate and really the fact that the hurricane performed as well as it did given my wiring was a credit to it.

So what did I find?  Firstly when I initially started the compressor I tested the voltage right at the switch and found it to be 12.4 volts with the engine running.  This was a bit low considering the voltage at the battery was 13.7 volts but even so the compressor still inflated the first tyre in around 3 mins as usual.  However this turned out to be great in comparison to the final readings.  For the final tyre the compressor took 5 mins 30 secs to perform the inflation and the voltage at the switch had dropped to 8.4 volts.  Worst of all I got a third degree burn (or so I made it out to be when I went looking for the sympathy nurse) when I accidentally touched a push together wire joiner.  I also discovered that the wires close to the compressor were also very hot.  Clearly the wiring system I had used just was not handling the current draw from the compressor so it was a case of completely rewiring.

Firstly I went to an Auto electrics store and got some decent 30 amp wire.  Secondly I took out all the push together joiners and soldered every join that was made.  Finally I shortened the earth lead so rather than running it all the way back to the battery as had been previously done I earthed it under the driver’s seat close to the compressor. 

The result!!  Beyond belief.  Initially the voltage was at 13.7 at the battery and 13.6 at the compressor which resulted in a 3 min flat inflation time.  For the final tyre the voltage was at 13.4 and the inflation time was 3 mins 15 secs.  A huge improvement and there didn’t appear to be any excessive heat build up along any of the new wires. 

After this success I then went and did the same for the wires that run to the back of the car for my Chescold fridge.  In a similar fashion to the compressor the fridge had never really worked very well in the car on 12 volts despite performing brilliantly on 240 volts or gas.  After rewiring and installing a heavy duty 50 amp plug it now freezes items inside whilst running on 12 volts.

I should point out that these performance issues are really only relevant to those things that are heavy uses of power.  Items such as radios, fluro lights etc don’t really require heavy wiring but for those items that do, do your wiring right the first time and feel confident that you won’t have to do the job again and that your equipment is performing at its optimum.

Let me give these tips on electrics though for any job that you do.  It will save you the frustration of fixing problems later or paying someone else.

1)       Solder every bear wire you can see.  Even if you use push together clips (avoid if possible) in your wiring leave a small amount of wire exposed and solder it onto the clip to get a good connection.  This will prevent moisture attacking the copper wire and causing corrosion which ultimately results in a poor contact and loss of power.

2)      Use blade type fuse holders and preferably water proof ones.  I’ve lost count of the number of times the screw together in line type holders have failed on me or worse still worked intermittently. 

3)      Cover all joins with either heat shrink or just as good is liquid electrical tape.  Not only does it make the finished job look professional but it also prevents moisture getting in to the wire.

4)      Never ever use the clips that many Auto Electricians use to join a wire onto your wiring harness.  These work (if your lucky) by cutting into the insulation of the main live wire causing a contact which then diverts a small amount of power to your accessory.  They are mainly used for wiring the cars tow plugs for a trailer.  I have found these clips to be the number one cause of problems with trailer lights not working.  For years I believed that it was poor quality trailer lights or plugs that would fail on my trailer (admittedly these often aren’t terribly good quality components) but more recently I have found the car’s electrics to be more of a problem than the trailers due to these clips.  These clips are not water tight so are a big problem in 4wds that do water crossings.  They let moisture in which corrodes the wires and again causes a bad connection.  The only reason Auto Electricians use them is because they are quick and easy saving them time.

5)      If you use a scrap piece of wire to complete a job ensure the wire itself has a nice golden copper colour to it.  If it is black then it has corroded so throw it away now and save yourself a headache latter.

6)      Leave extra length in your wires so they aren’t stretched tight around corners.  Making your wires tight will cause it to rub and eventually short out.  Use rubber grommets (available form Super Cheap) when ever the wire passes through a hole to prevent chaffing and shorts.

Well I think that is enough for now.  Learn from the countless mistakes I have made on this issue and do the job right the first time.

All the best

Trevor

PS:  Trev’s Tips can now be found on our clubs web page if you ever need to look up an old repair tip.