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AussiePeej
Newbie

Joined: 18/04/2010
Location: Australia
Posts: 1

Posted: 04:49pm 17 Apr 2010

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Hi all,

New to this forum, it's now 2.30 in the morning and I've been reading for hours. Having fun. Anyway, I've used the search function quite a few times and it's answered a few questions but hoping I can get some guidance.

I was given a stepper motor.. I lent a mate my engine hoist and he gave me this motor. It's an 80v, 2 phase, 2.85Amp 4 wire BiPolar motor. He bought it from ebay but didn't use it. What output could be expected from a motor like that, if any?

To give you an idea what I want to do. We love camping and I'm starting a teardrop trailer build, setting it up for 12v/240v power. I was thinking of a couple of solar panels but also a small windmill set up (perhaps sliding the pole into welded brackets on my bull bar and then a few guide wires to pegs and roof rack).
Anyhoo. I've worked out our energy requirements and whilst solar should do, backup wind would be good.

Now, my other question is.. the MPPT regulator I've got my eye on is 12/24/48v but in the literature it will take from 12 - 55Vin. What if the windmill produces more than that? Not that I actually expect it to but let's for argument's sake say it generated 80v. How could I reduce that to 12v. If it generated at 2.85Amp, by reducing the voltage, would that increase the output amps?

And finally, those cheap amp meters on ebay, amp meter, can they just be wired in series to the motor if I spin it using a drill (apprentice carpenter, I have lots of drills

) will that tell me what's being produced or is that too simple?

Thanks in advance for any help and sorry if it's basic stuff but I'm just starting out on all this.

Cheers
Craig

Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333

Posted: 04:08am 18 Apr 2010

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AS for your amp meter question yes but no.

Yes you can wire it direct in line but only after you have rectified the AC power generated to DC. (Its a DC meter)
You will need 2 bridge rectifiers ..one on each coil with the dc outputs paralleled together.

Firstly big steppers dont make very good generators due to the cogging effect they suffer bad from.
This causes allsorts of starting problems and anything less than a gail it will be likely to sit there and do nothing (just ask Mac about that problem)

The higher the rpm the higher the voltage out, so to keep the upper voltage down it is required to keep the mill output loaded to control the rpm.
This is why when the battery is full we need to use a dump load to sink the power into, so as to control the mill.
Most voltage controllers work on the prinicable that once the line voltage reaches a preset limit it switches the power over to a dump load till the line voltage falls to a lower preset limit and then switches back to the battery.
In doing so the voltage should never get outside the safe operating limits and the mill will be controlled via power loading.

A good dump load for camping would be a suitable water heater as it is only need to waste power and hot water whist camping is always good.

Pete.

Sometimes it just works

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