Ammeter - Which, How.

[DeanS]

Chris Pink told me to get an ammeter.

So I am.

but I'm not getting the one he sent me (ebay) because it was a combo and I already have a voltmeter arriving.

 

My alternator is 175Amps.

 

Anyone got any links, for the size I should get, and where I can get it. I'm cruising round Manchester, but I could arrange it to be delivered to our marina mooring. I was hoping that maybe Maplin sold something, but doubt it.

[Chalky]

You'll need a 2 part solution - a shunt and a meter. The shunt is a precision resistor that you connect onto the cable that you want to measure the current in. Make sure that the shunt is rated to handle the current + a generous safety margin and is continuously rated for the load. The shunt will need to be placed somewhere where it can dissipate heat since it may get hot during use. It will have 4 connections, 2 at each end. The big bolt connections are used to connect your power cables, the smaller screw terminals (called the Kelvin connections) are used to connect the shunt to the meter. The meter can be placed any where convenient however you'll want to use a good quality cable to connect it (with fuses at the shunt end) - ideally twisted pair or screened to avoid noise pickup.

 

Maplin won't sell anything like this. Try Radio spares or Farnell - this is industrial quality kit not toy stuff.

 

Alternatively look at some of the standard marine battery monitors since they're designed to handle this kind of power using a shunt / meter configuration.

[Chris Pink]

I only advised you on that one because a ) it had the shunt with it and b ) it didn't need a separate power source and was therefore an easy shout.

 

so you need a 200A meter that looks vaguely like that one off eBay then a matching shunt (will be in the listing). Check for one that will run off the source you are measuring. Alternatively (clever tip) power it from your start battery and measure your leisures.

 

by all means go to Radio Spares or Farnell if you want to pay 5 times as much. or get a monitor if you want to pay 10 times as much.

 

....and please don't shout at me.

 

...and don't waste your time and money running your engine 8 hours, run it for 2-3.

[Chalky]

200A shunt £24.38

 

http://uk.farnell.com/datel/3020-01101-0/shunt-50mv-200a/dp/1339341

 

500A shunt £24.38

 

http://uk.farnell.com/datel/3020-01103-0/shunt-50mv-500a/dp/1339342

 

Data sheet

http://www.farnell.com/datasheets/67361.pdf

 

Meters to suit are in the £20 - £50 region (or you can use a cheaper meter if you know how to do the maths to calibrate it).

 

Have a look at the data sheet, especially the bits about de-rating the system.

[smileypete]

Chris Pink told me to get an ammeter.

So I am.

but I'm not getting the one he sent me (ebay) because it was a combo and I already have a voltmeter arriving.

 

My alternator is 175Amps.

 

Anyone got any links, for the size I should get, and where I can get it. I'm cruising round Manchester, but I could arrange it to be delivered to our marina mooring. I was hoping that maybe Maplin sold something, but doubt it.

If you just want something for NOW then Maplins do a DC clamp meter that reads up to 400A for £40:

 

http://www.maplin.co.uk/dc-ac-current-clamp-multimeter-629713

 

Then you could buy something mail order at your leisure. The cheapest stuff comes from the far east but can take some weeks to arrive, maybe sending it to another boater who could send it on to you would be best.

 

cheers, Pete.

~smpt~

[Richard10002]

Get a NASA BM2 for about a hundred quid. Its where you'll end up after messing about with other, cheaper, stuff.

 

How do I know?

[steelaway]

Chris Pink told me to get an ammeter.

So I am.

but I'm not getting the one he sent me (ebay) because it was a combo and I already have a voltmeter arriving.

 

My alternator is 175Amps.

 

Anyone got any links, for the size I should get, and where I can get it. I'm cruising round Manchester, but I could arrange it to be delivered to our marina mooring. I was hoping that maybe Maplin sold something, but doubt it.

 

Hi

 

 

I fitted one of these - My link - 5 years ago and it has been faultless.

Connect shunt into negative as near to the battery's as possible.

I only have it reading the domestic battery's.

Send me your email and I can send you the fitting instructions

 

Alex

[smileypete]

Get a NASA BM2 for about a hundred quid. Its where you'll end up after messing about with other, cheaper, stuff.

 

How do I know?

What ones did you get that didn't work? I'm sure Chris would recommend something that's very likely to work OK.

 

If buying from Ebay I'd tend to buy from a supplier that specialises in them.

 

cheers, Pete.

~smpt~

[GUMPY]

If you just want something for NOW then Maplins do a DC clamp meter that reads up to 400A for £40:

 

http://www.maplin.co.uk/dc-ac-current-clamp-multimeter-629713

 

Then you could buy something mail order at your leisure. The cheapest stuff comes from the far east but can take some weeks to arrive, maybe sending it to another boater who could send it on to you would be best.

 

cheers, Pete.

~smpt~

£29.99 on ebay same thing......2day delivery

280830929313

Edited April 4, 2013 by Loddon

[bizzard]

What about building into your boats instrument panel an average quality Multimeter (say £8) to check battery voltage ect by just the turn of its knob. Cut the probes off and wire it to the battery circuit. And with a system of wiring and switches to switch change overs could also be wired to check mains power and Ohms.

Most multimeters can only check low amperage though I think 10 or 15amps, over that and they'd probably go off pop. They don't like eating Am's so don't make very good Am-eaters, not hungry enough.

Edited April 4, 2013 by bizzard

[valrene9600]

Get a NASA BM2 for about a hundred quid. Its where you'll end up after messing about with other, cheaper, stuff.

 

How do I know?

I have a BM 1 with 100amp shunt. Unable to fit in my system as i have a 3000w inverter.

Nasa told me it can be wired around the inverter by wiring the inverter to the non load side of the shunt.

 

Not sure how to do this but was thinking would it not be easier to wire it to the 12v battery isolator switch which is seperate to the inverter isolator switch.

 

All I want to do is see what is going in from the solar panels and what is being used on the boat.

NOT interested in monitoring the inverter as it is only on for wash machine or power tools.

[smileypete]

£29.99 on ebay same thing......2day delivery

280830929313

Well spotted! The UK price and availability has got better since I last looked at these on Ebay.

 

There's also Mastech ones at the same price, spec is about the same but they take 3 AA batts which are also included, instead of the 9V ones which I'm not so keen on:

 

http://www.ebay.co.uk/itm/271084217607

 

cheers, Pete.

~smpt~

[costalot]

I have a BM 1 with 100amp shunt. Unable to fit in my system as i have a 3000w inverter.

Nasa told me it can be wired around the inverter by wiring the inverter to the non load side of the shunt.

 

Not sure how to do this but was thinking would it not be easier to wire it to the 12v battery isolator switch which is seperate to the inverter isolator switch.

 

All I want to do is see what is going in from the solar panels and what is being used on the boat.

NOT interested in monitoring the inverter as it is only on for wash machine or power tools.

 

Les, At the moment all your domestic return (negative) wires terminate on the negative battery terminal of the domestic battery bank. To measure what's happening with your solar panels and boat electic's you need to connect one side of the shunt to the battery negative terminal and all the existing negative wires (except the inverter negative) to the other side of the shunt (that is; take them off the battery terminal and fit them to the other side of the shunt). Wire the shunt to the meter in accordance with the installation diagram. By leaving the inverter negative wire directly connected to the battery negative terminal the electricity used by the inverter will bypass the shunt and not be measured by it.

 

However doing this will not allow you to accurate see what amps are actually being taken from the batteries because you won't see the effect of the use of the inverter. You might be able to fit a larger shunt (check with NASA) which will allow you to also measure the use of the inverter.

[valrene9600]

Les, At the moment all your domestic return (negative) wires terminate on the negative battery terminal of the domestic battery bank. To measure what's happening with your solar panels and boat electic's you need to connect one side of the shunt to the battery negative terminal and all the existing negative wires (except the inverter negative) to the other side of the shunt (that is; take them off the battery terminal and fit them to the other side of the shunt). Wire the shunt to the meter in accordance with the installation diagram. By leaving the inverter negative wire directly connected to the battery negative terminal the electricity used by the inverter will bypass the shunt and not be measured by it.

 

However doing this will not allow you to accurate see what amps are actually being taken from the batteries because you won't see the effect of the use of the inverter. You might be able to fit a larger shunt (check with NASA) which will allow you to also measure the use of the inverter.

Now if I remember correctly the inverter wires come from one of the batteries and the other electricals come from another. Assume this is because the mega thick cables would be to much on one terminal.

So as long as i leave the inverter wires alone and just wire the shunt to the other terminal all will be well.

I assumed that the electricity would wizz around the wires and blow the shunt.

So are you saying that the inverter draw of power from battery will only flow down the one lead?

Sorry but I need to be clear about it all as i`m not an expert.

[Paul C]

Get a NASA BM2 for about a hundred quid. Its where you'll end up after messing about with other, cheaper, stuff.

 

How do I know?

 

This is very good advice!

[steelaway]

Now if I remember correctly the inverter wires come from one of the batteries and the other electricals come from another. Assume this is because the mega thick cables would be to much on one terminal.

So as long as i leave the inverter wires alone and just wire the shunt to the other terminal all will be well.

I assumed that the electricity would wizz around the wires and blow the shunt.

So are you saying that the inverter draw of power from battery will only flow down the one lead?

Sorry but I need to be clear about it all as i`m not an expert.

 

 

 

Hi

 

The inverter will be fed by two wires, one from the red / live terminal of your domestic bank of battery's and one from the black / negative.

These will be big cables but there will be further big cable from the same battery bank to supply the fuse board and all other 12V appliances.

The shunt is fitted in series, that is in line, with the main black wire from the battery bank.

If there is more than one black wire they need to arranged so that only one cable leaves the battery bank - or you will only read the current going either to the inverter or the fuse board.

This one cable may need to be even bigger to take the current of the others.

 

I hope this makes it a bit clearer.

 

Alex

[valrene9600]

Hi

 

The inverter will be fed by two wires, one from the red / live terminal of your domestic bank of battery's and one from the black / negative.

These will be big cables but there will be further big cable from the same battery bank to supply the fuse board and all other 12V appliances.

The shunt is fitted in series, that is in line, with the main black wire from the battery bank.

If there is more than one black wire they need to arranged so that only one cable leaves the battery bank - or you will only read the current going either to the inverter or the fuse board.

This one cable may need to be even bigger to take the current of the others.

 

I hope this makes it a bit clearer.

 

Alex

Problem is the shunt is unable to handle the inverter so I need to go around it. There are two blck wires from the batts as i said above. One inverter and one to 12v in boatvia fuse panel.

I am getting the impression that if i use only the 12v cable to attach the monitor all will be well.

So now i`m getting confused and can see the monitor going back in the cupboard for another 2 years.

Please someone clarify this in simple terms.

[costalot]

Problem is the shunt is unable to handle the inverter so I need to go around it. There are two blck wires from the batts as i said above. One inverter and one to 12v in boatvia fuse panel.

I am getting the impression that if i use only the 12v cable to attach the monitor all will be well.

So now i`m getting confused and can see the monitor going back in the cupboard for another 2 years.

Please someone clarify this in simple terms.

 

Les, I replied to your msn email address

[steelaway]

Problem is the shunt is unable to handle the inverter so I need to go around it. There are two blck wires from the batts as i said above. One inverter and one to 12v in boatvia fuse panel.

I am getting the impression that if i use only the 12v cable to attach the monitor all will be well.

So now i`m getting confused and can see the monitor going back in the cupboard for another 2 years.

Please someone clarify this in simple terms.

 

What size are the shunt and ammeter?

 

Alex

[valrene9600]

Les, At the moment all your domestic return (negative) wires terminate on the negative battery terminal of the domestic battery bank. To measure what's happening with your solar panels and boat electic's you need to connect one side of the shunt to the battery negative terminal and all the existing negative wires (except the inverter negative) to the other side of the shunt (that is; take them off the battery terminal and fit them to the other side of the shunt). Wire the shunt to the meter in accordance with the installation diagram. By leaving the inverter negative wire directly connected to the battery negative terminal the electricity used by the inverter will bypass the shunt and not be measured by it.

 

This is confusing, maybe not for someone confident with wiring but it is for me.

3 leisure batts

1st batt neg has inverter cable connected

2nd batt neg has 12v supply to fuse board

3rd batt neg just links to other batts as is norm

 

So can I use 2nd batt neg to connect shunt?

Will 1st bat neg that has inverter cable just carry on supplying inverter and not go through shunt.Which is fine for me.

 

What size are the shunt and ammeter?

 

Alex

shunt is 100amp Not ammeter but BM1 nasa battery monitor

 

Les, I replied to your msn email address

Ok thanks MSN is old account .will check and see if forum has new email

[MoominPapa]

I have a BM 1 with 100amp shunt. Unable to fit in my system as i have a 3000w inverter.

Nasa told me it can be wired around the inverter by wiring the inverter to the non load side of the shunt.

Won't this render the amp-hour counting function of the BM1 useless? If it can't integrate the current being used by the inverter it stands no chance of telling you useful information about state-of-charge.

 

MP.

[valrene9600]

ok checked e mail and it is on the hotmail account. Thanks, in touch soon

 

Won't this render the amp-hour counting function of the BM1 useless? If it can't integrate the current being used by the inverter it stands no chance of telling you useful information about state-of-charge.

 

MP.

As i have said above i am not interested in SOC just what solar is putting in and what is being consumed by the 12v in the boat.

The monitor was bought in ignorance(100amp shunt!!!) some 2 years ago and I need to make some use of it.

[steelaway]

ok checked e mail and it is on the hotmail account. Thanks, in touch soon

 

 

As i have said above i am not interested in SOC just what solar is putting in and what is being consumed by the 12v in the boat.

The monitor was bought in ignorance(100amp shunt!!!) some 2 years ago and I need to make some use of it.

 

 

 

Buy another one? ----My link

 

Alex

[smileypete]

This is confusing, maybe not for someone confident with wiring but it is for me.

3 leisure batts

1st batt neg has inverter cable connected

2nd batt neg has 12v supply to fuse board

3rd batt neg just links to other batts as is norm

 

So can I use 2nd batt neg to connect shunt?

Will 1st bat neg that has inverter cable just carry on supplying inverter and not go through shunt.Which is fine for me.

Yes, then shift the fuse board negative to the non battery end of the shunt.

 

The current though the inverter return will then bypass the shunt.

 

cheers, Pete.

~smpt~

Edited April 6, 2013 by smileypete

[valrene9600]

Many thanks to all those who have posted advice.

I now have a clear picture of the way to install the meter.

Many thanks everyone