Power Dynamo for GT750

[Suzukidave]

I was thinking these units would make more power than the stock alt. but i see beside powering there own CDI ignition it doesnt put out but 80 watts where the stock alt. puts out 280 watts ? ............................................................................................................................Shipping to U.S. via UPS
130,00 €

Shipping to U.S. via DHL
50,00 €

80 watts is the highest output

Price:

powerdynamo suzuki gt 750
description (in English: ignition for vintage motorcycl

price in Euros for export outside EU: 352.9
+ 130,00 EUR UPS
or
+ 50,00 EUR DHL




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With best regards, Mit freundlichen Grüssen,
Recevez mes sincères salutations, Un cordial saludo
Daniel Köhn


Powerdynamo GmbH, Straße am Heizhaus 1, 10318 Berlin
info@powerdynamo.biz Tel +49 (0)30 50173520
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[jabcb]

80 watts is the highest output

I've wondered about this too. Did you have them confirm this?

80W max alternator output for lights wouldn't be enough for lighting on a stock GT750. At low rpm output would be perhaps 60W.
Those numbers are T500-like values, which has a 35/25W headlight & a battery charging current of < 3A with the high beam on.

See pages 16 -- 18 in: http://www.ozebook.com/compendium/suzi/suzidata1.htm

[Suzukidave]

Under the dotted line is there reply back to me when i asked about the output and the cost shipped to the US . I was a bit surprised at the low output myself . Maybe 80 watts as its rated as DC ? http://www.powerdynamo.biz/deu/systems/lists/suzuki.php" onclick="window.open(this.href);return false;

[jabcb]

Suzuki provides the DC specs on pages 16 -- 18 in: http://www.ozebook.com/compendium/suzi/suzidata1.htm

The GT380/GT550/GT750 curves are for 14V DC.
The GT750 alternator outputs 20A at a little over 2k rpm, which is 280 watts.
The Denso GT380/GT550 alternator outputs 20A at a little over 2k rpm, which is 280 watts.
Even the lower-output Kokusan GT380/GT550 alternator outputs 10A at a little over 2k rpm, which is 140 watts.

The points ignition system has 4 ohm coils and a dwell of around 180 degrees.
The points ignition system uses about: 14 / 4 * 3 * 180/360 = 5.25A, which is about 70 watts.

That leaves about 70 or 210 watts at a little over 2k rpm for lights & battery charging.

With only 80W max, the Powerdynamo doesn't look to make much sense for the GT380/GT550/GT750.

[argo1974]

Powerdynamo stuff is actually produced in Chech Republic by a company named VAPE.
I have 2 of their early 12V/180W units running in my JAWA 350cc 2-strokes with great results. Unfortunately VAPE changed the way magnets were attached to the rotor few years ago. They just used some kind epoxy for fitting them. Since then, I've heard of lots of expensive damages due to loosening magnets. Being not enough, they converted the outer pickups to internal ones, cutting significantly the output power of the unit. Avoid them.

[jabcb]

Bummer...

Link to the VAPE website: http://www.vape.cz/en/technologie/alternatory/" onclick="window.open(this.href);return false;

Now that you mentioned it, the VAPE logo is easy to recognize on the parts shown on Powerdynamo's website.

[tz375]

VAPE components are used by several European manufacturers.

80w cannot be correct.

Polaris, Suzuki and Yamaha that I know of and probably others can produce an alternator that generates 280 or so from a similar unit with perhaps a slightly different configuration. Even with a slow speed and high speed exciter coils they should be able to achieve more than that.

That's why I suspect that the quoted number is incorrect.

Magnets are usually bonded in place with epoxy resin of some sort, so there's nothing odd about that aspect of their design & manufacturing process. If theye were able to use those super thin rare earth magnets, the size could be significantly reduced.

May have to go back to the snowmobile systems that SuzukiDave was looking at.

[jabcb]

Did a Google search & found forum postings for other types of bikes where the owners lamented about meager alternator output.

Alternator description page on VAPE website has links for graphs of alternator output.
Curve for ~ 80W alternator: http://old.vape.cz/images/charka_altern ... nitrni.gif
Curve for ~ 180W alternator: http://old.vape.cz/images/charka_altern ... nitrni.gif

80W might actually be correct.

[tz375]

That is so low that it defies logic as to why it's on the market at all. There has to be a stronger alternator available for a different application. Sled units are a little larger and tend to fit a much larger diameter shaft with double row bearings. They are hardly a straight swap.

I just checked the pictures and it's a small diameter rotor and with thick magnets, there isn't much space inside for copper in there. Polaris units are much larger OD and have enough space for a lot more copper.

It makes me wander what other rotor/stator units are available. The simple solution is probably three small inductive ignition units with 3 pickup and a single hall effect rotor, and keep the stock alternator. I have tried Ignitech programmable and a 3 unit DYNA and neither is a simple bolt on.

[argo1974]

Low output of newer style VAPE ignition units is not caused by their size since early units with outer pickups were capable for 180W.
Those early ones had 12 magnets inside the rotor and all 12 stator coils were intended for power delivery.

In newer units, some of the stator coils (I've counted 8 remaining coils on some units) were replaced at least by 2 pickup coils. And, non-magnetic plates were added to the rotor between the remaining magnets. For ignition pulses, a non-magnetic plate has to bridge the pickup coils with its tips. For example, on a triple engine with 120 degree firing order, with 8 power coils only plus 3 non-magnetic plates, low power output is not a mystery.

I know several guys in here having had problems with loosening magnets. Those units were not replaced on warranty, but resellers/factory blamed them having too much play in crank bearings. Though, in most cases the bikes were just taken to the road after complete restoration, including rebuilt cranks + new bearings, for the first or second time.

[Suzukidave]

I am sooooo glad i ran this thread before thinking about getting one of these units for more output in case i need it .

[arneg]

Digging this one out... I put this system on my RD350 and am extremely happy with it (less vibration, better starting, no more points maintenance, better lights, feels better at low RPMs due to advance, easier jetting) - but it has 150W on that bike (external pick up).

Reading this:

Suzuki provides the DC specs on pages 16 -- 18 in: http://www.ozebook.com/compendium/suzi/suzidata1.htm

The GT380/GT550/GT750 curves are for 14V DC.
The GT750 alternator outputs 20A at a little over 2k rpm, which is 280 watts.
The Denso GT380/GT550 alternator outputs 20A at a little over 2k rpm, which is 280 watts.
Even the lower-output Kokusan GT380/GT550 alternator outputs 10A at a little over 2k rpm, which is 140 watts.

The points ignition system has 4 ohm coils and a dwell of around 180 degrees.
The points ignition system uses about: 14 / 4 * 3 * 180/360 = 5.25A, which is about 70 watts.

That leaves about 70 or 210 watts at a little over 2k rpm for lights & battery charging.

With only 80W max, the Powerdynamo doesn't look to make much sense for the GT380/GT550/GT750.

I was thinking: the 80W provided is after the spark. So it's still 10W more than the Kokusan ignition. Shouldn't that be sufficient? Also, if I do the math (55W headlight, 10W rear, 10W for the idiot lights) there's still a few watts left for charging?

[jabcb]

No, the Dynamo on the GT750 puts out something like 50W @ 2k rpm. See:
http://old.vape.cz/images/charka_altern ... nitrni.gif

After deducting power for the coils, the Kokusan on the GT380/GT550 puts out something like 70W @ 2k rpm.
After deduction power for the coils, the Denso on the GT750 & GT380/GT550 puts out something like 210W @ 2k rpm.

The Dynamo is a much better choice on the twin cylinder bikes, such as the T500 and your RD350.
On the T500 it puts out something like 80W @ 2k rpm. See:
http://old.vape.cz/images/charka_altern ... nitrni.gif

Take a look at the Dynamo parts for the GT750 & RD350 to see why.
More of the rotor & stator is allocated to the alternator for the RD350 than the GT750, so the RD350 has a more alternator output.
Pic of parts for the GT750: http://www.powerdynamo.biz/deu/systems/7328/pack.jpg
Pic of parts for the RD350: http://www.powerdynamo.biz/deu/systems/ ... 05pack.jpg

Modern ignition systems provide the benefits you mentioned.
Its just that on the GT-series triples there are better choices that are cheaper.

[arneg]

thanks for the prompt reply. I seem to be one of those idiots that needs to hear twice. cheers!