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Re: Wiring an ammeter

To: JeffreyLos <JeffreyLos@aol.com>, spitfires <spitfires@autox.team.net>
Subject: Re: Wiring an ammeter
From: Richard B Gosling <Gosling_Richard_B@perkins.com>
Date: 11 Jul 2000 04:20:38 -0500
Jeff,

I'm not a total electrical guru, but since no-one else has answered your post I
 thought I'd pass on my thoughts.

The instructions sound reasonable to me.  I'm not sure what is meant by a #10
 wire - maybe this is an American standard?  Basically, the wires to and from
 the ammeter should not carry too much current - after all, you are expecting
 the reading to be 0 if all is as it should be.  The wire should be capable of
 carrying the maximum current that will occur if either the alternator is bust,
 so your battery is being drained, or if your battery is flat and your
 alternator is charging it - this is the sort of information you are after, so
 you don't want the wires to melt and the ammeter to be disconnected just as it
 starts to tell you something useful!  Given that all the current drawn has to
 pass through one of three fuses, rated at ?? constant current (can't remember
 the value off the top of my head, you'll have to check it!), then your wires
 to and from the ammeter should be capable of carrying 3*?? without
 over-heating or melting.

Yes, using a decent quality connector sounds much easier than splicing - which
 I always have doubts over, since you usually end up wrapping your final join
 in electrical tape, and then in a couple of years it starts to come off and
 leave bare wire which can short out - and at this point it is not even fuse
 protected, so you will have a nice meltdown and lots of smoke.  Of course, if
 you use a decent heat-shrink sort of insulating material that is probably OK,
 but a connector capable of handling the max. current described above would
 still be easier!

One major point, make sure that the ammeter is NOT carrying the current to the
 starter motor, as this will end up blowing practically every wire in the
 system!

Hmm, just re-checked your post, and it doesn't mention wires going to the fuse
 box.  Although I think that everything that goes to the fuse box goes to the
 ignition switch on the way, and you do mention a wire to the ignition, so I
 guess that is OK.

I don't see any problem with taking the supply to the fuel and temp gauge
 lights and using that to supply your ammeter light.  If you have a dimmer (my
 1500 doesn't, but by the sounds of other peoples posts some cars do) then the
 same part-way dimmer setting will give a slightly dimmer light all round, but
 max. setting should still be the same.

Everybody please feel free to criticise my advice above - as I said I'm not an
 expert, just someone who has done a fair bit of fiddling about, I only offer
 what I can since (at least when the last digest was sent out) no-one else
 seems to have volunteered any advice.

Richard and Daffy

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