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Auto elec ammeter wiring
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<blockquote data-quote="Geoff1946" data-source="post: 496054" data-attributes="member: 28452"><p>Yes, good points, you don't want to be creating a fire hazard. If your meter is constructed as I described it will be VERY low resistance. It would be great if you had the means to measure it, but I guess that unlikely.</p><p></p><p>Do you have any electrical measurement instruments, either to determine the meter resistance or to measure current in the ranges we are discussing? </p><p></p><p>Now a shunt to double the range, i.e. make actual 40 amps read as 20 on the dial, the shunt would be the same resistance as the meter. So, in practice you are probably talking about a length of cable, and a very low power loss/heat generation. In fact the power dissipated between the shunt and meter will be exactly what is being dissipated inside the meter now.</p><p></p><p>Hence your fire hazard is only from a short circuit, not from normal operation.</p><p></p><p>If you are concerned to reduce the overall fire risk on your car, consider adding a fusible link by the battery as is modern car practice.</p><p></p><p>How is the meter wired physically? Do both leads go into the engine compartment, or is the output connected to the rest of the dash/car systems? (I have an outline of an idea in mind dependant on the answer to that)</p></blockquote><p></p>
[QUOTE="Geoff1946, post: 496054, member: 28452"] Yes, good points, you don't want to be creating a fire hazard. If your meter is constructed as I described it will be VERY low resistance. It would be great if you had the means to measure it, but I guess that unlikely. Do you have any electrical measurement instruments, either to determine the meter resistance or to measure current in the ranges we are discussing? Now a shunt to double the range, i.e. make actual 40 amps read as 20 on the dial, the shunt would be the same resistance as the meter. So, in practice you are probably talking about a length of cable, and a very low power loss/heat generation. In fact the power dissipated between the shunt and meter will be exactly what is being dissipated inside the meter now. Hence your fire hazard is only from a short circuit, not from normal operation. If you are concerned to reduce the overall fire risk on your car, consider adding a fusible link by the battery as is modern car practice. How is the meter wired physically? Do both leads go into the engine compartment, or is the output connected to the rest of the dash/car systems? (I have an outline of an idea in mind dependant on the answer to that) [/QUOTE]
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