Ammeter switch

[Ric]

I have solar-panels, a wind-generator and hydrogenerator. Currently the output from all three is fed into a single ammeter. I'd quite like to be able to switch the ammeter to check output from each source individually, as well as the total.

Does anybody know what sort of switch would do this?

 

[VicS]

Not easy unless you use an ammeter with an external shunt.

Then use three shunts, one permanently in the wiring from each source.

Switch the meter itself between the shunts with a 2 pole 3 way ( rotary) switch

If desired a fourth shunt in the common wiring and a 4 way switch so that you can monitor the total current

 

[theoldsalt]

VicS,

Your reply confused me somewhat.

My immediate though was of the ammeter output wired to the battery and a 1,2,3,all switch on the input to the ammeter.

Could you explain why that would not work ?

 

[VicS]

VicS,

Your reply confused me somewhat.

My immediate though was of the ammeter output wired to the battery and a 1,2,3,all switch on the input to the ammeter.

Could you explain why that would not work ?

Because you would only be connecting one source at a time.
I assume the OP wants all three sources to be operational simultaneously but to be able to monitor the output from them individually or the combined output as at present.

 

[Dave_Seager]

I think that you would need three 2-way switches, one for each power source. Then you could switch the power input between the input side of the ammeter and the battery. The current would then either flow through the ammeter to the battery or bypass the ammeter and go directly to the battery. Ideally, the switches should be make-before-break to avoid possible damage to alternators in the wind and hydro generators. Standard 1-2-both battery switches could probably be used as they are normally used to protect alternators.

 

[VicS]

I think that you would need three 2-way switches, one for each power source. Then you could switch the power input between the input side of the ammeter and the battery. The current would then either flow through the ammeter to the battery or bypass the ammeter and go directly to the battery. Ideally, the switches should be make-before-break to avoid possible damage to alternators in the wind and hydro generators. Standard 1-2-both battery switches could probably be used as they are normally used to protect alternators.

If you use three ( or four) shunts you dont have to worry about any of this make before break malarkey.
All the power sources are permanently connected via the shunts.
All you then switch are the connections to the meter itself. Relatively light duty switches are adequate and provided it is fused relatively light wiring can be used too.

 

[halcyon]

Not easy unless you use an ammeter with an external shunt.

Then use three shunts, one permanently in the wiring from each source.

Switch the meter itself between the shunts with a 2 pole 3 way ( rotary) switch

If desired a fourth shunt in the common wiring and a 4 way switch so that you can monitor the total current

Or just hang a Hall effect sensor on each cables, and feed the output via a single pole 4 way switch.

What would be useful is what current is the OP measuring, and details of the ammeter.

Brian

 

[VicS]

Or just hang a Hall effect sensor on each cables, and feed the output via a single pole 4 way switch.
Brian

Thats an even better idea ........ what's a Hall effect sensor?

 

[theoldsalt]

Halcyon

Good idea

VicS

The Hall Effect

http://en.wikipedia.org/wiki/Hall_effect


Hall Effect Sensors

http://uk.rs-online.com/web/c/?sear..._EEM_SCP_Research-_-hall effect sensor_Phrase

 

[halcyon]

Thats an even better idea ........ what's a Hall effect sensor?

Okay I'll buy it.

The Hall effect shunt is in two parts, sensor that fits on the cable and measures the magnetic field, and the driver that converts the output to suit the particular ammeter fsV and amps reading.



Brian

 

[theoldsalt]

Ric,

An alternative, and maybe simpler solution might be to just add a couple more ammeters. They are resonably cheap and saves the complexity of external shunts (choose those with internal shunt) or Hall effect sensors and switches. They are also easier to wire in, especially for us amateurs.

 

[noelex]

Something like the Sterling battery monitor would do what you want, at a price, but you would get a lot of extra information.

 

[halcyon]

Something like the Sterling battery monitor would do what you want, at a price, but you would get a lot of extra information.

If spending money you could fit a bar-graph, showing battery volts, total charge amps, plus amps from all three charge sources, displaying all at the same time. The Hall sensors wire direct to bar-graph, so no switch, and no wire mods.

At the end of the day, it's how much the OP wants to pay and how complex, you could just buy 3 digital ammeters on ebay, then add 3 shunts.

Brian

 

[noelex]

The ability to count AHrs makes power usage management much easier. This can only be done with a battery monitor.
3 digital Ammeters would be cheaper, but will give far less useful information.

 

[halcyon]

The ability to count AHrs makes power usage management much easier. .

But the OP only has a ammeter, and three charge sources, he was only trying to check what the output is from each of the three.

Brian

 

[CreakyDecks]

Assuming that the system has diodes in each line, so that the generators can't feed back into each other, then you could possibly derive the current going through each diode by measuring the voltage across each of them. It would need a bit of electronics to convert the very non-linear diode voltage into a current reading!

 

[Sandyman]

If spending money you could fit a bar-graph, showing battery volts, total charge amps, plus amps from all three charge sources, displaying all at the same time. The Hall sensors wire direct to bar-graph, so no switch, and no wire mods.

At the end of the day, it's how much the OP wants to pay and how complex, you could just buy 3 digital ammeters on ebay, then add 3 shunts.

Brian

I would go along with that. Simplest solution. Recently did the exact same thing. Cost less than 50 quid including 3 digital voltmeters. If looking on ebay go for digital meters which include shunts.

 

[Amulet]

Wow - what a place to learn - I enjoyed the Wikipedia article hugely. But I can't see how you calibrate it to give you amps.

I solved the problem with two NASA battery monitors. They have had some bad press on the forums, but have performed faultlessly for me. ... actually I lie... one day I went to the boat after a few days to discover it reading a discharge of 130 amps! This should have boiled my battery so clearly was guff. I switched the BM off and on to let it recalibrate and it has behaved ever since.

 

[theoldsalt]

May I please raise another point from curiosity.

If you are trying to charge batteries from several sources they will probably be generating different voltages.

My simple mind tells me that only the device generating the highest voltage will be charging the batteries. The other devices (through their controlling circuits) will be dormant. If so then only one ammeter will be giving a reading.

Could someone comment please.

 

[noelex]

Wow - what a place to learn - I enjoyed the Wikipedia article hugely. But I can't see how you calibrate it to give you amps.

I solved the problem with two NASA battery monitors. They have had some bad press on the forums, but have performed faultlessly for me. ... actually I lie... one day I went to the boat after a few days to discover it reading a discharge of 130 amps! This should have boiled my battery so clearly was guff. I switched the BM off and on to let it recalibrate and it has behaved ever since.

I am glad its worked for you, but a battery monitor is much more useful if it can display and integrate the value of all the shunts.
This way you can get a net A in or out as well as AHrs in or out.
A single battery monitor with the capicity to deal with the shunts you require is usually a better choice.
If it can be integrated with the regulators to provide intelligent charge termination that is even better, but this is a more sophisticated system than the OP needs.