volt meter

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Mario60
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Forename: Mario
Surname: Sciriha
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volt meter

Post by Mario60 » Tue Jan 28, 2020 2:27 pm

hi, just acquired a volt meter. Can anyone advise me how to connect it.
Many thanks in advance
Mario
Mario Sciriha
1972 MGB roadster
1971 MGB GT (for restoration)
1979 Honda CB650Z
1975 Kawasaki S1C 250
1974 Suzuki GT380
1979 Suzuki TS125
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Peter Cresswell
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Location: Stone, Staffordshire

Re: volt meter

Post by Peter Cresswell » Tue Jan 28, 2020 5:32 pm

Hi Mario
Looking at your list of cars your MGBs are all Negative earth with an alternator. A voltmeter simply connects between a convenient place across any live feed to the earth (car body). I think I would be tempted to wire it between the Brown wire at the fuse box to the terminal marked positive (with either +ve or simply + ) on the back of the voltmeter using a brown (or red) wire , and the negative terminal ( -ve or simply -) on the back of the voltmeter to a convenient body earth point using a black wire. The voltmeter should then read 13V -ve when the ignition is turned on. It will drop to around 12V when cranking and then show 13V with the engine running. If it doesn't read or tries to kick to the left on the dial then reverse the connection on the back of the voltmeter.
Voltmeters are only sensing instruments and don't have high currents passing through them so the job of wiring them up is straightforward. The reading they give shows the condition of the battery. Around 13V is normal for a battery in good condition, below 12V it is likely to need changing soon.
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965
Vic Butler
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Re: volt meter

Post by Vic Butler » Tue Jan 28, 2020 7:11 pm

I have to disagree with Pete. The meter should be connected to the connection on the ignition switch which becomes live when the ignition is switched on (not the auxiliary position. Connecting to the nearest ignition controlled source or fuse results in low readings because of voltage drop. The voltmeter on my. Land Rover is connected to an ignition controlled fuse and it reads just about 13 volts but 13.8 volts is the reading across the battery on a fast tickover.
Connecting it straight to the switch avoids voltage drops. I'll be reconnecting the meter to the switch.
1977 Stage 2 MGB GT
1975 SWB Series 3 Land Rover with a later 2.5 petrol engine
Ian Fozzard
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Re: volt meter

Post by Ian Fozzard » Tue Jan 28, 2020 9:43 pm

Bearing in mind my previous acknowledgement that autoelectrics are not my strongest suite, I can say that I use a simple digital voltmeter which plugs into my MGB cigarette lighter socket. Live when the ignition is switched on of course. That could be the simplest location on the dash to make a connection perhaps? Reads around 12.5 - 13v when switched on, and then around 13.5v with the engine running.

No holes in the dashboard required and it gets unplugged and placed in the glovebox when not needed.

Ian F
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Peter Cresswell
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Re: volt meter

Post by Peter Cresswell » Thu Jan 30, 2020 4:46 pm

Hi Mario,
Ignore my advice. Vic's method of connection is far better. If you do it the way I suggested, the voltmeter will read all the time, even with the ignition off (unless you have an electrics isolation switch). So not a good idea!
Also I think the voltmeter will draw a small amount of current so would flatten the battery over time if you do as I suggested.
Sorry for the confusion,
Pete
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965
Mario60
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Joined: Thu Jul 18, 2019 9:34 am
Forename: Mario
Surname: Sciriha
Location: Malta

Re: volt meter

Post by Mario60 » Fri Jan 31, 2020 8:53 pm

hi all,

Many thanks for your advice. As usual really find them helpful

regards

Mario
Mario Sciriha
1972 MGB roadster
1971 MGB GT (for restoration)
1979 Honda CB650Z
1975 Kawasaki S1C 250
1974 Suzuki GT380
1979 Suzuki TS125
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