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suggs

wiring a volt meter?

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i want to fit a volt meter to my 200tdi 90, are they all the same with a live and neutral. do they wire direct to the battery with another lead going to a live from the lighting circuit..

cheers

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i want to fit a volt meter to my 200tdi 90, are they all the same with a live and neutral. do they wire direct to the battery with another lead going to a live from the lighting circuit..

Simple things voltmeters -- an earth connection and a V+ connection.

You can connect the earth to the most convenient earth point (but do check to make sure it's a good earth). The V+ connection must be taken from the switched +12V NOT from a permanently live +12V feed otherwise you'll discharge the battery if it's left long enough. Doesn't have to be any particular +12V switched feed -- just tap into the most convenient +12V switched feed for wherever you've put the voltmeter.

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any White wire off the ignition switch will do, [ignition switched live feed] & a earth & gauge illumination into the existing gauges red/white lighting wires.

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thanks for the reply's

if i wire it to say the cigi lighter etc it will show if the volts drop below 12v but will it also show if they rise too high, for instance if the alternator regulator packs up and starts to over charge/boil the battery. thats why i was thinking direct to the battery so it shows what the alternator is pushing out.

but as you say i hadnt thought about the discharging issue, could i wire one to the alternator

cheers

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cig lighter is usually live at all times, I wouldn't use that as the power source. don't connect to the alt, go for a white ignition controlled feed, I used a piggyback spade terminal off the ignition switch to power my voltmeter, it shows the charge rate well,if you connect to the battery or a permanent live feed the voltmeter will read all the time even with the engine/ignition off.

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ok will do that

but im not great with lecy work, so i remove the cowling around the ignition and T into the white lead. is there just the one white lead as i dont want to be cutting into the wrong wire.

thanks for the help

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Whilst the voltmeter draws very little current, and therefore is not badly affected by bad connections causing resistance, if you wire it in to the dash loom on the same wires as other devices, which are drawing current, you will be measuring the effective voltages due to the resistances in the circuit of the devices you have tapped in to.

I'm being pedantic, but if you want to measure the absolute battery voltage, rather than just observe a relative change, you need to connect the voltmeter directly to the battery, with a small relay to disconnect it when the engine is off.

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with a small relay to disconnect it when the engine is off.

like this :D

post-20-1211808782_thumb.jpg

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ok will do that

but im not great with lecy work, so i remove the cowling around the ignition and T into the white lead. is there just the one white lead as i dont want to be cutting into the wrong wire.

thanks for the help

took mine off the ign switch one of the white wires, doesn't seem to matter which one as the see alternator voltage when the engine is running.

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took mine off the ign switch one of the white wires, doesn't seem to matter which one as the see alternator voltage when the engine is running.

ok thanks for the advice mate

cheers

Harry

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