Need to find an alternator

[Electric-T]

I'm dreaming up a new project. I need to find a 50W alternator. It needs to put out 12 vdc at 4.5A. I cant find one. I'm leery of making my own because ive never done it before. If anyone can help out id appreciate it

 

[kellys_eye]

Try using a larger stepper motor - they are commonly used in 'demo-style' wind turbine applications but I'm not entirely sure what power output they give but larger version may just top the 50W mark perhaps???

<update> I've seen a webpage that reports a type 34 stepper outputting around 20W at 1000rpm. Maybe steppers aren't the best way to go after all???? Unless you have access to a pretty hefty one!

Given the relative rarity of small alternators maybe you should just go for the smallest one you can find in a domestic vehicle? I have a couple of new alternators (for a micro hydro system) that cost $50 on eBay - NOS from older cars and good for 65A @12V

 

[Minder]

Do you need an alternator for DC, A DC motor will generate.
Or a BLDC motor with a 3phase bridge.
Also Auto wreckers are a cheap source of alternators.
M.,

 

[Electric-T]

A wind turbine is exactly what im going for. The project is a solar/wind charging bank. Ive got my battery: 12v 4.5Ah secondary cell
May need more than one i guess.
My solar panel: 50w 12vdc output with controller. Just need the wind generator now. If i knew a good software id draw you a schematic. The biggest problem is finding an enclosure for the batteries and charging circuit.

 

[Electric-T]

Do you need an alternator for DC, A DC motor will generate.
Or a BLDC motor with a 3phase bridge.
Also Auto wreckers are a cheap source of alternators.
M.,

I need to use it to charge a 12v 4.5Ah gel battery. I think most auto alternators would over charge a cell like mine

 

[Minder]

There are quite a few forums out there for wind generators, both DC and AC sources are out there,
Although a bit over kill in this case , the auto alternator may be the quick fix.
M.

 

[kellys_eye]

Most gel cells only require a 0.2C charge current (in your case 0.9A) so a 50W charger is over the top for your needs.

 

[Minder]

I guess what it comes down to, is a toss up between designing a custom regulated motor or a alternator.
M.

 

[Electric-T]

My mistake i was confused with another battery i looked at. https://www.ebay.com/p/12v-4-5ah-le.../1104511125?iid=140917767576&trdt=0&rdtsrc=vi
This is my battery. Is 0.1C a recommended charge rate for this cell? I realize 1C is a little intense

 

[Electric-T]

I guess what it comes down to, is a toss up between designing a custom regulated motor or a alternator.
M.

I better start looking into making my own alternator then haha

 

[kellys_eye]

Anything UNDER the recommended charge rate is fine - just like discharging a battery can cause damage/shortened life, so can over charging.

A 500mA charge rate is more than adequate in most standby circuits and a simple stepper motor based alternator/generator will be able to keep that charged. 6W can be delivered by a type 34 stepper at only a few hundred rpm.

 

[Minder]

Personally a stepper motor would not be my first choice by any means, the nature of the output and the natural cogging effect would deter me.
I would prefer a DC motor or a BLDC if wishing to go brushless, a BLDC generates 3 phase when back fed.
M.

 

[Electric-T]

Personally a stepper motor would not be my first choice by any means, the nature of the output and the natural cogging effect would deter me.
I would prefer a DC motor or a BLDC if wishing to go brushless, a BLDC generates 3 phase when back fed.
M.

I will look into a BLDC motor. As soon as I finish the design I will post it in projects. Critism is more than welcome.