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Multimeter reading of 17v

hackenbush

By hackenbush
in New to Boating?

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hackenbush Collaborator

hackenbush

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I've just bought this multimeter from Maplin:

http://www.maplin.co.uk/p/dmm-st-921-digital-multimeter-n81ee?cmpid=ppc&gclid=Cj0KEQiAguXBBRCE_pbQ5reuq8MBEiQANji2LR6lfedKwF7-zln8soy-ZsrJKa8Tm3MYPhpDxxuvKaEaAgK88P8HAQ

 

And frankly I'm a little lost as to how to use it. I switched it to dc volts and attached it to my leisure battery and got a reading of 17v. Am I doing something wrong or is my battery in some kind of dangerous state or is this even normal?

 

I also bought clips with it in the hope that I could attach the multimeter to the battery and monitor charge or have I bought the wrong meter for this. The guys at Maplin barely knew more than me

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dmr Veteran II

dmr

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17 volts is very wrong (unless you have a 24 volt boat but even then its still wrong).

I expect you are doing something daft with the meter.

 

Get an AA battery (1.5volts) and one of the little square batteries (9volts) and play with the meter to make sure its ok and you know what you are doing, all a bit easier and safer than messing with big batteries.

 

..............Dave

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cuthound Veteran II

cuthoundDonate to Canal World

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Digital multimeters can be woefully inaccurate if the internal battery is nearly flat.

 

Check again against known battery voltages, as suggested above, (set to dc, usually shown by a solid line above a dotted line) and if still wrong replace the internal battery and try again.

 

If still wrong take it back.

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WotEver Veteran II

WotEverDonate to Canal World

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Ok, still not sure I'm doing this correctly but I've tested it with an energizer AA battery. The switch is aimed at a V with a squiggly line beside it and the screen says "DC" but the reading is1.6v! As it stands that's the only unused battery type I have to hand

Well that's correct.

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Geo Rising Star

Geo

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Ok, still not sure I'm doing this correctly but I've tested it with an energizer AA battery. The switch is aimed at a V with a squiggly line beside it and the screen says "DC" but the reading is1.6v! As it stands that's the only unused battery type I have to hand

 

Now without changing the settings go and measure the voltage on your starter battery. If you have a charger running and are on a shoreline turn the charger off first and wait half and hour.

A reading of 1.6v is correct or how I've set it up is correct or both?

 

Both it would seem :)

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hackenbush Collaborator

hackenbush

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Now without changing the settings go and measure the voltage on your starter battery. If you have a charger running and are on a shoreline turn the charger off first and wait half and hour.

 

Both it would seem :)

Ok, I've actually got the engine running so I'm guessing turn it off and wait half an hour?

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Geo Rising Star

Geo

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Ok, I've actually got the engine running so I'm guessing turn it off and wait half an hour?

 

Yep :)

Only if you are moored!

 

lol No it won't go anywhere on a canal, now the sea lol

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MtB Veteran II

MtBDonate to Canal World

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Ok, I've actually got the engine running so I'm guessing turn it off and wait half an hour?

 

 

Not necessarily. It's just that we need to know if the engine was running, or not, when you measure the battery voltage.

 

WITH the engine running I'd expect something around 14.2V dc. With the engine OFF I'd expect something between 12.0 and 13.0V dc, depending on about a million different factors.

 

But 17V is NOT ok, under any circumstances, other than a flat meter battery (in which case its a false reading).

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hackenbush Collaborator

hackenbush

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That's weird. The sqiggly line next to a straight line means AC measuring. The DC settings have a straight line with a dotted straight line next to it.

 

To be honest the line is so small it looked squiggly. I have got it on the right setting though.

The good news is that I've tested it again and am getting a realistic reading.

The bad news is that reading is 11.72. This seems low. Am I dealing with a battery close to defunct?

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Martin Megson Rising Star

Martin MegsonDonate to Canal World

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To be honest the line is so small it looked squiggly. I have got it on the right setting though.

The good news is that I've tested it again and am getting a realistic reading.

The bad news is that reading is 11.72. This seems low. Am I dealing with a battery close to defunct?

 

11.72 is very low unless there is a heavy draw on the batteries.

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Geo Rising Star

Geo

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Posted (edited)

To be honest the line is so small it looked squiggly. I have got it on the right setting though.

The good news is that I've tested it again and am getting a realistic reading.

The bad news is that reading is 11.72. This seems low. Am I dealing with a battery close to defunct?

 

Which battery is that ?

 

And what sort of battery is it seal or can you add water?

Edited by Geo
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