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jenevers

Mysterious 5amp drain

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All the 230volt and 12volt appliances on my boat are switched off, apart from the 2 bilge pumps (one 12v and one 230v) which have float switches, so are also “off”.

My Mastervolt 12/2000 Inverter is “on” in case the 230v bilge pump needs to kick in.

The Mastervolt MICC has a LCD display. So why does it display “-5Amps”, which is draining my Trojans????

Where is this power going? I thought it might be the inverter but when I switch it off there’s still a drain of 5 Amps going somewhere.

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You say the inverter is off? Pull its fuse or isolate it from the battery.

TV aerial amplifier. Fridge. gas alarm. USB socket. Gas stove ignition.

Edited by Boater Sam
added more

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The inverter consumes energy even if nothing is connected. Change the bilge pump to 12V D.C.  

 

Edited by MartynG
.

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10 minutes ago, jenevers said:

All the 230volt and 12volt appliances on my boat are switched off, apart from the 2 bilge pumps (one 12v and one 230v) which have float switches, so are also “off”.

My Mastervolt 12/2000 Inverter is “on” in case the 230v bilge pump needs to kick in.

The Mastervolt MICC has a LCD display. So why does it display “-5Amps”, which is draining my Trojans????

Where is this power going? I thought it might be the inverter but when I switch it off there’s still a drain of 5 Amps going somewhere.

So its about 60 watts - not big enough to be a 'heating appliance' (like an Immersion heater), but too big to be the inverters 'stand by current'.

 

It's about 'right' for a fridge, a computer or something of similar size.

 

Turn all of your master switches off - does it still show -5a ?

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4 minutes ago, MartynG said:

The inverter consumes energy even if nothing is connected. Change the bilge pump to 12V D.C.  

 

Fatuous and entirely irrelevant post of the day.

16 minutes ago, jenevers said:

All the 230volt and 12volt appliances on my boat are switched off, apart from the 2 bilge pumps (one 12v and one 230v) which have float switches, so are also “off”.

My Mastervolt 12/2000 Inverter is “on” in case the 230v bilge pump needs to kick in.

The Mastervolt MICC has a LCD display. So why does it display “-5Amps”, which is draining my Trojans????

Where is this power going? I thought it might be the inverter but when I switch it off there’s still a drain of 5 Amps going somewhere.

At a pinch you could disconnect the services side of the shunt and see what it says, but I think the most likely explanation is an offset on the measurement of shunt current.

Edited by nicknorman

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A couple of weeks ago I noticed a spurious drain of about 10 amps. We did have the inverter on (we rarely use it) so I went round the boat and turned all the 240 volt stuff off but still had the ten amp drain. Horrible 240v failure with cables melting into polystyrene insulation went through my mind.   Then remembered that the battery charger was on!  I can thus confirm that Battery-inverter-charger-battery is not a source of perpetual motion bug consumes over 100W 😀

 

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

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24 minutes ago, MoominPapa said:

Shorted alternator diode?

 

MP.

Had that happen with a 90 AMP.Alternator ,checked Engine for Oil water etc.and noticed that one Alt. had a warm casing even though it had not run for 12 Hours.the other two Alts. were stone cold.

New Diode pack and all was well.

Well Spotted MP

  • Greenie 1

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1 hour ago, Robbo said:

A clamp meter is a useful thing for confirming and finding these type of issues.

 

Probably not accurate (or repeatable) enough for such a low current.

 

The OP could try setting his Multimeter to DC millivolts,  and measure the voltsge being dropped across the shunt. This will be proportional to the mV rating of the shunt, (if it is, say, a 100 amp shunt at 75 milli volts,  and reads 3.75 milli volts,  then that equates to 5 amps).

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20 minutes ago, cuthound said:

 

Probably not accurate (or repeatable) enough for such a low current.

 

The OP could try setting his Multimeter to DC millivolts,  and measure the voltsge being dropped across the shunt. This will be proportional to the mV rating of the shunt, (if it is, say, a 100 amp shunt at 75 milli volts,  and reads 3.75 milli volts,  then that equates to 5 amps).

5amps is defo enough for a clamp meter to see and check.

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4 minutes ago, Robbo said:

5amps is defo enough for a clamp meter to see and check.

 

Debatable, very dependent on the quality of the meter used and access to ensure the conductor can pass through the centre of the jaws and at 90° to them, hence my repeatability comment.

 

I agree you are likely to get a reading but it may well be inaccurate.

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11 minutes ago, Robbo said:

5amps is defo enough for a clamp meter to see and check.

 

I agree. My UNI-T clamp meters are not very consistent measuring what I know to be the same current but I'd certainly trust them to confirm the presence (or otherwise) of a current as high as 5A. 

  • Greenie 1

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42 minutes ago, cuthound said:

Probably not accurate (or repeatable) enough for such a low current.

It shouldn't matter about repeatability - any reading when everything is switched off is a cause for concern - doesn't matter if the 1st time it shows up as 5 amps and the 2nd time as 2 amps, and the 3rd time as 7 amps - It shouldn't show anything.

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The UT-203, along with other such meters I suspect, has a relative mode. You hold the meter (jaws closed) near the wire in question and press the relative button, which zeros the display. Then when you put the wire inside the jaws, local errors due to stray magnetism, and sensor offset errors, are eliminated.

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20 minutes ago, cuthound said:

I agree you are likely to get a reading but it may well be inaccurate.

It may be inaccurate, but we are not trying to find out where milliamps is going, even if it's as much as a amp out it will still standout like a flashing beacon.

  • Greenie 1

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47 minutes ago, Alan de Enfield said:

It shouldn't matter about repeatability - any reading when everything is switched off is a cause for concern - doesn't matter if the 1st time it shows up as 5 amps and the 2nd time as 2 amps, and the 3rd time as 7 amps - It shouldn't show anything.

 

Depends on how many devices are drawing current. If only one I agree, but if two or more, it is helpful to be able to "follow" the current through the circuits and have them add up to the total at the shunt.

45 minutes ago, nicknorman said:

The UT-203, along with other such meters I suspect, has a relative mode. You hold the meter (jaws closed) near the wire in question and press the relative button, which zeros the display. Then when you put the wire inside the jaws, local errors due to stray magnetism, and sensor offset errors, are eliminated.

 

I have a UT-203 and whilst it is a great meter for the price and perfectly adequate for use on a boat, it is far from what I used to use in my working life in terms of proven accuracy.

45 minutes ago, Robbo said:

It may be inaccurate, but we are not trying to find out where milliamps is going, even if it's as much as a amp out it will still standout like a flashing beacon.

 

Depends on whether there is more than one device draining the battery, as explained above.

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10 minutes ago, cuthound said:

 

Depends on how many devices are drawing current. If only one I agree, but if two or more, it is helpful to be able to "follow" the current through the circuits and have them add up to the total at the shunt.

And using a multimeter is the perfect tool to troubleshoot and follow current!

 

11 minutes ago, cuthound said:

I have a UT-203 and whilst it is a great meter for the price and perfectly adequate for use on a boat, it is far from what I used to use in my working life in terms of proven accuracy.

We are not wanting it for accuracy, we are wanting it to just detect current, it doesn't matter if it's out.

 

13 minutes ago, cuthound said:

Depends on whether there is more than one device draining the battery, as explained above

Not really.

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20 hours ago, cereal tiller said:

Had that happen with a 90 AMP.Alternator ,checked Engine for Oil water etc.and noticed that one Alt. had a warm casing even though it had not run for 12 Hours.the other two Alts. were stone cold.

New Diode pack and all was well.

Well Spotted MP

That’s interesting. I’ll check. There are definitely NO appliances switched on anywhere, just bilge pumps on standby and the inverter.

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6 hours ago, jenevers said:

That’s interesting. I’ll check. There are definitely NO appliances switched on anywhere, just bilge pumps on standby and the inverter.

 

On 07/11/2018 at 13:51, cereal tiller said:

Had that happen with a 90 AMP.Alternator ,checked Engine for Oil water etc.and noticed that one Alt. had a warm casing even though it had not run for 12 Hours.the other two Alts. were stone cold.

New Diode pack and all was well.

Well Spotted MP

Checked the alternator. Stone cold....dammit!

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