Kubota Dynamo

[pietenpol2002]

I'm needing help with planning the electrics for the Yanmar clone. I'd like to abandon the clone's anemic charging system and just dispatch it entirely. In it's place I have a bunch of the small Kubota dynamos, one of which I'd like to mount to be belt driven. They're single phase 12V and rated at 14 amps, however you can find reports of their output ranging from 8 amps to the "rated" 14 amps. So, if we go with worst-case-scenario, the question is whether 8 amps would be sufficient. I would need enough to charge a small battery (no starter), a 55W headlamp, LED tail, no indicators, a horn and a sprinkling of gauge lamps. Because these dynamos are not regulated, any excess is dumped into the rectifier and dissipated in the form of heat. In the interest of reducing losses and excess heat, it's best to design quite close to the demand. So, if 8 amps is 96 watts how close am I?
My knowledge of electrics is limited - it runs downhill like water, right? Anyone able to help those of us so obviously challenged in the area of electrics?

[Nanko]

A DC tot DC converter is the way to go.
It regulates output voltage without dissipating the excess power.
I found this one : http://www.ebay.com/itm/GRAPE-Waterproo ... 2c6b76e18c.

But maybe there are better choices.
The voltage from the alternator can go sky high without load,over the 40 Volt this type can handle.
Check before connecting the converter.
Ofcourse the output from the alternator has to be rectified with a diode bridge and a capacitor.

Edit) Not sure if this particular one is the high efficiency switched mode type.
The large heatsink probably means its an ordinary(dissipative) regulator

[pietenpol2002]

Again, my ignorance on the subject will be obvious, but my understaning is that these dynamos (used by Kubota, Yanmar, John Deere and others) are a permanent magnet unit that produces 12V AC and rated at "approximately 14 amps". Many were upgraded to the 20 amp model to run more lights. Because of the upgrade, the small versions are readily available at a very reasonable price. The 14 amp version like I have is also what's being used to upgrade vintage Douglas, Vincent, Sunbeam and Indian bikes, in part because they are so small as to be hidden inside the original dynamo/generator housings. Perhaps that statement answers my question. If they can power those bikes with original lights, I ought to be able to power mine with the use of LED's.

Here's an example used in an aircraft application (however it's the 20 amp version).

http://www.n56ml.com/corvair/dynamo.html

Scoll down to the second and third option on the page below for a look at the the 14 amp version and the rectifier/regulator. But often found for 1/4 that price.

http://www.iowamotorparts.com/kubota_alternators.htm

[Nanko]

These dynamo's are perfect to feed a DC to DC converter.
Ofcourse the AC voltage has to be rectified before connected to a DC DC converter.
A simple diode bridge and a electrolitic capacitor is all you need.
The only concern is the unloaded voltage form the alternator,it can reach 60 Vac.
If that is too much for the converter there should be always a consumer connected (headlights)
Or some kind of voltage limiter.
A switched mode converter uses PWM ( pulse width modulation) to regulate the output voltage,very little energy is dissipated,worst case some 10%
They can handle large voltage differences on the input.

[alexanderfoti]

Why not rewind the stator in the yanclone?

I can get around 11 amps out of mine after I rewound it:

some more info:

http://fotifixes.com/2012/05/26/diesel- ... update-10/

That post is a bit sparse with any information, but I can help to answer any questions.

[alexanderfoti]

In hindisght those little dymamo/alternators would be a good option to boost the output.

Any idea where to get one in the UK without paying stupid money?

[pietenpol2002]

Here's one option, even if a bit pricey.

http://tinyurl.com/lwpkc3n

And for your application you could drive it off the third sheave of your pulley since you only need 2 for power transmission to the gearbox. Or, since the body turns with the pulley, you can also use the whole unit as a belt tensioner. Has one moving part and a rebuild consists of 2 $5 bearings.

[alexanderfoti]

That's not too bad. Although I can get a new one from America for that money, and just ship it to my cousin.

Exactly. It's easy just to buy a bigger belt then run it in the middle in a triangle layout, as I have lots of space behind my engine.

I'm only thinking of using one as a backup plan not sure what the loads etc will be like in the depths of winter. Headlights, cooling fans etc etc at least I have a charge and voltage indicator.