Ametek 30 being stingy with current

[SamDelux]

Hi Everyone!

I've been following this board for a while and the time has finally come for me to ask a question of my own. I'll try and keep it as short as possible.

I'm a complete noob with electricity / wind power / engineering - it's been many years since my school science lessons! My only knowledge comes from the internet so go easy on me! 

I'm wanting to build my own wind turbine and to start with I've been tinkering around with some parts to try and get the basics sorted before upscaling. So this is the problem that I have:

I bought myself an Ametek 30 VDC generator and I have it connected to a 6V, 1.3Ah lead acid battery. I have a diode connected on the +'ve side that's rated to 3A. I've tested the generator and it puts out a nice voltage when spinning even slowly (I'm talking about a 7-9V output when spun by hand or slowly using a drill). When I measure the current though I'm getting a paltry 60mA!

All the data that I've read on these motors says that I should be getting in the region of 1 - 2.5A at this voltage.  (Obviously, correct me if I'm wrong).

This is a photo of the setup:

This is a photo of the battery:

This is the diode that I'm using: http://www.maplin.co.uk/p/1n5400-3a-silicon-rectifier-ql81c

So really my question is: what am I doing wrong? Why can't I produce decent current?

Thanks in advance for any help! 

[Mary B]

What is the battery voltage when you start? Those are capable of around 5 amps output so a 1.2 ohm load or a 30 watt low voltage light bulb would be a better test. If your battery is charged then you will see very little current produced because there is no need for it.

[SamDelux]

Ahh I didn't know that happened...

Just tested it and it says 6.1V so guess I should discharge it a bit and try again?

[john8750]

Try about a 20 ohm 25 watt resistor to put a load on the motor( generator), or a light such as a head lamp bulb. Place the ammeter in series with the resistor and motor wires. This should show some current. Also look to see if the motor states HP or current draw. It could be a low powered servo motor. If it states current or watts, you can't expect more than that out.
Welcome, I'm new here also.
BTW, I have a 100 volt ametek motor. Gonna to make a pedgen.   

John Smith

[birdhouse]

i'm guessing the goal is to charge a 12v battery? 

when i was doing tests, i'd hook my motor to the desired battery voltage i'd be charging (24v in my case).  then i'd also hook a load to the battery. then a bicycle speedometer to the motor shaft(you can get rpm with rough math).    the load connected to the battery would be about what i expected the motor to put out.  this would keep the battery volts from rising too quickly as i spun the motor with a drill. 

then throw an ammeter in line and you've got output amps, volts, and RPM.  the three basic things needed to deduce a blade size and type (tsr). 

adam

[SamDelux]

@John  I shall certainly give that a go. I'm guessing the resistors are widely available

@Adam Yes, that's the eventual goal. I wanted to do it on a small scale for the time being just so that I can get to grips with the principles.

So putting a load in the circuit seems like the best course of action! I shall give it all a go and report back.

Thanks

Sam

[SamDelux]

Hi guys

So, I still intend to get a resistor for my testing but in the meantime I've discharged the battery a bit. At different stages of discharge I was repeating the original test and I was indeed starting to get an increase in amps when I spun the generator - up to about 200mA at one point.

Now though, I've discharged the battery so that it reads 5.75V and when I do the original test I get zero current and can't even get a reading out of the generator above 5.65V. Is it that I've just discharged the battery too much? Or have I done something stupid like break my multimeter 

Thanks again

Sam

[tanner0441]

Hi

From the motor plate what is the spindle speed when it is running on its design voltage. I have several Amtek motors and 5000 RPM is not unusual.

Spinning by hand or slowly with a drill is not helpful for working out how useful it will be as a generator. If the slow speed on your drill is 800 RPM that is on the quick side.  That is only with a six volt battery, you are aiming for twelve.

When your motor voltage equals the battery voltage you have reached cut in as the speed increases the voltage will rise, if there is a battery as a load it will hold the voltage down so the current will start to climb as the speed goes up.

Divide the spindle speed by the voltage and you will have some idea how many turns per volt you will get.

Brian

[Mary B]

Check your diode, it may have given up the ghost. The Ametek 30 should be capable of up to 6 amps into a 12 volt battery. Also make sure you were using the correct amp scale on your meter and did not blow a meter fuse. Data on it, shorted amps isn't very useful http://greenterrafirma.com/ametek-data.html

Can you take a picture of your test setup? Might let us see a mistake you may be making.

[SamDelux]

When your motor voltage equals the battery voltage you have reached cut in as the speed increases the voltage will rise, if there is a battery as a load it will hold the voltage down so the current will start to climb as the speed goes up.

Ok, I see. This is a handy piece of info.

When you say 'motor plate' do you mean this pathetic little sticker?


@MaryAlana
There's a pic of my setup in the first post, if my attachment worked that is!
You know what? I think I've blown a meter fuse. When I plug into the mA socket I get a zero reading and it's very easy to turn the generator (suggests open circuit because it's broken?). When I plug into the A socket then I do get a bit of a reading and it's harder to turn.

So I think tomorrow I'm going to exchange the meter (only bought it the other day ) and I'm going to upgrade the diode to a higher amperage and give that a go.

[Darren73]

you have probably blown the fuse in your meter for the mA range which is why it's reading zero and easy to turn. I made a similar mistake many years ago when I was just starting to learn about electricity and current.

[SamDelux]

Yep, that's almost certainly what I've done.

So, I connected a resistor and it seems to have improved things - I'm now getting about 0.02A. This is obviously still low though so I think I may have to add a bigger load. Will get myself a light bulb connected up.

One thing that's puzzling me though is that if I remove the diode from the circuit and let the 6V battery power the motor I get 0.16A on the ammeter. How comes then that when I spin the generator at the same speed with the diode in place that I get the 0.02A reading instead of 0.16A? Is it to do with the diode?

[john8750]

Ametek motor plates usually have only the voltage, and maybe the speed. The rest is only production info we don't need. Most were used for precision tape drive motors.
Like mentioned, your motor might have an operating speed in the thousands. Best to find a motor with a higher operating voltage, like 100.
You are most likely overloading the motor with the battery having a very low internal resistance of being overly discharged. Do check the Diode and the meter fuse. And try the headlamp check, or maybe a tail light. Just hook it up to your motor, and spin it. Set the meter to 10 amp current scale. You don't need the Diode for this test.
Hope you get it working. Keep the fun in it....

John Smith

[tanner0441]

Hi

 The motor plate should have the voltage and the RPM on it. Divide the RPM by the voltage you need, say 14 for a 12V system. That will tell you the speed your turbine needs to turn at. The best Amteck motors are the low speed 90V versions, you can also get a 130V model.

Read back through the threads on here, there are numerous threads on the pros and cons of Amteck motors used as turbines, another thing you have to watch is the bearings, they are not designed to run 24/7.

Where in the UK are you I have several PM motors I found for wind turbine projects ranging from 100 to 240W versions, they are under my bench and you could have them. I also have a treadmill motor and it doesn't take much looking to see which is best and why.

Don't connect your meter across  the motor on amps, it will tell you nothing and destroy your meter.  Short circuit current will not tell you how much power you will generate. Power is volts times amps, if you short the motor out it will be zero volts, zero times anything is zero.

As I say look back at some of the threads on this site, there is all the information you need, someone has already done what you want to do and it will be cataloged.

Brian

 

[Mary B]

That is not the "good" Ametek 30 motor, part number is wrong. Doesn't mean it won't put out some power but it is an unknown. The number in the upper right is the part number and it was partly blocked, has the K in it. Can you give me that entire number?

One the ma scale you produced more power than the meter could register and blew the fuse. On the A(mps) scale the reason it turns hard is because it is trying to produce output. Hook it up to a cordless drill on the low speed range and try it. Make sure to mount the motor down tight or hang onto it.

Your meter is fine(maybe a blown fuse internally). the ma scale is milliamps or thousandths of an amp. Max range on most is 1 amp so you may have created at least an amp with your testing. The A scale is amps and the max will depend on the meter, usually will say on the front panel.

.16amps is the no load current draw of that particular motor and doesn't mean much.

[SamDelux]

Thanks for all the help and advice so far people - you've been fantastic. Never imagined that this would end up being so fun either!

Don't connect your meter across  the motor on amps, it will tell you nothing and destroy your meter. 

Yep almost certain that's what I did on the mA scale. Oh well you live and learn...

Ok, so what I've done is to simply hook up the generator to a couple of light bulbs and give it a spin. I can now get a peak reading of about 1A just by turning it by hand so I'm guessing that the Ametek is still good and useful.

Am I right in believing that the more discharged a battery is the more current it'll draw from the generator? Also, which battery would draw more current; a 6V half-charged unit or a 12V half-charged one?

Thanks once more

Sam

[tanner0441]

Hi

The current from your generator is governed by the size of the winding. If the winding will handle 5A then at 5A it will last. Your 5A generator will be capable of delivering more than 5A but not for long, but your 5A generator will put 5A into a 6V battery or a 12 or even 24V battery, it will just need to spin faster. The power of a generator is normally in Watts. so your 6V battery with 1A is 6W, your 12V battery with 1A is 12W.  Voltage is measured across the battery, current is measured in series with the load.

As the voltage increases the wire gauge can be reduced for the same amount of work which is why 48V is often the voltage of choice for serious off grid systems.

Where you are where I was about 5 or 6 years ago, I would put a prop on anything that would turn, I have the scars and bruises to prove it. I found out people selling motors on Ebay can be very cavalier with the truth when describing motors to be used as generators. I have a 12V traction motor from a fairground ride under my bench, big, low speed, and powerful, as a generator? Total waste of time. I have motors from electric scooters and go-carts, waste of time. In the end I bought a couple of meters, one reads 15V full scale the other 10A full scale and built myself a test rig, a 12V battery, and several bulbs with lengths of wire on to use as loads. If ultimately you want a 12V system go for 12V straight off.

Brian

[SamDelux]

The current from your generator is governed by the size of the winding. If the winding will handle 5A then at 5A it will last. Your 5A generator will be capable of delivering more than 5A but not for long, but your 5A generator will put 5A into a 6V battery or a 12 or even 24V battery, it will just need to spin faster. The power of a generator is normally in Watts. so your 6V battery with 1A is 6W, your 12V battery with 1A is 12W.  Voltage is measured across the battery, current is measured in series with the load.

Ahh ok that's good to know

Where you are where I was about 5 or 6 years ago, I would put a prop on anything that would turn, I have the scars and bruises to prove it.

I know exactly what you mean! I did this on Saturday trying to teach myself how to solder!

[john8750]

Sorry about that. You will catch on. Just keep the fun in it.........

John Smith

[Mary B]

Rule number one when solder: If you drop the iron DO NOT try to catch it! I still have that scar 40 years later 

[DamonHD]

Ouch!