Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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malcolmzilla
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Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby malcolmzilla » Wed Jan 03, 2018 12:16 pm

Was looking for more than the paltry 30W (2.5A) DC the stock KTM XC/XCW/EXC stator (08-15?) puts out to the battery...

Namely to run some grip heaters for my delicate wee girly meat hooks, and maybe also a LED headlight, so I can see the tree I'm going to hit...
Running either of these (necessities?) from the battery on my 14 TE would drain it in short order...

Some report that grip heaters work on AC... I'm no sciencegeer however, but Symtec's on high DC will dry out my gloves palms, mmmmmm... Since I regularly stop on the trail to make (ahem intentional) snow angels. :D

Didn't really want to buy another TT full DC stator system ($300), nor did I want to float the ground and solder the OEM unit, etc.

From a post on ThumperTalk, some guys have been using the AC lighting circuit (~70W, at full rpm) and adding a $20 AC to DC rectifier (max 3A) from eBay, and successfully running LED's.

Ordered one up:
https://www.ebay.com/itm/LED-RECTIFIER-AC-to-DC-LED-CONVERTER-USA-FULL-WAVE/391304590098?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

IMG_0425.JPG


Shows up in about a week. Potted, water resistant. Its -28 out, so time for an garage session and beta test.

IMG_0421.JPG


From the XC/XCW wiring diagram (found online for free, so caveat emptor), it looks like the AC comes right off the stator unregulated.
Checking with my Fluke... 11.8 max V AC...

IMG_0424.JPG


Wire up rectifier into the AC lighting leads, and a jumper for the light switch... Test DC output off rectifier... 10.5 V DC max, and didn't let the smoke out, so at this juncture, it's not a rectiFIRE...

IMG_0428.jpg


Bit of voltage loss, pushing through the diodes. Google-fu tells me the voltage loss means the diodes may be more robust and can take >3A... but the AC stator is 70W nominal so 5.8A full roar - 3A seems like a safe factor of ~50%.

Added a 3A fuse to the rectifier DC output to protect the rectifier, and ultimately the stator as I prefer riding to hiking (although a fair portion of my time is spent walking along side my bike in the bush)...

Add in the grips, fire it up, test, instant good heat, didn't blow fuse on "high".

Not sure how clean the power is, that's oscilloscope testing action I think. Not in my laboratory anyhow.

So rather than sacrifice a Baja Designs Squadron or a TrailTech HID, I hooked a cheap chinesium 18 W DC LED flood (5v-20V input rating), and it also ran nicely, maybe some flickering at idle, by eye-o-meter. For a heated grip resistor element I'm sure its acceptable.

Anyhow, spent a good 3 hours riding with the grips on high from the rectifier, and no (electrical) issues from the bike.
I'll watch for a cheap LED to mount to the bars.

Rubber side down, hope this helps, no warranty is expressed or implied.
15 Yamaha YZ250FX, 270cc, cams
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Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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AJRJ
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby AJRJ » Wed Jan 03, 2018 1:13 pm

Nice job!

Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby Rider Eh! » Wed Jan 03, 2018 1:15 pm

Link to thumpertalk post? I may do this...
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby malcolmzilla » Wed Jan 03, 2018 4:10 pm

I will have to do a bit of searching, I didn't book mark the post on TT, but the fella was running a 30 watt chinesium LED with no ill effects. Was in the KTM 2 stroke section...

Maybe a full regulator / rectifier is better? $50 EG: https://fortnine.ca/en/ricks-motorsport-electrics-rectifier-regulator
Being an enginerd, hoping you will translate this electropixiespeak for us luddites. :D :cheers:
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby malcolmzilla » Wed Jan 03, 2018 4:17 pm

15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby dirtyboy » Wed Jan 03, 2018 4:35 pm

I'm almost convinced to do this. My internal it-nerd has almost grasped the concepts. :lol:

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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby axel99 » Wed Jan 03, 2018 8:25 pm

Nice. You mentioned are hooking into the un-regulated AC directly off the stator. I have a feeling you are tapped into a regulated AC lighting circuit(this is good), I thought the XC's had from factory. Just want to be clear so guys don't have a recti"fire" under the gas tank :crazy:. If you rev out the bike and dont get much over 13v AC on the rectifier input you installed...you get to keep all your body hair and you are on a usable circuit. Otherwise you can ditch your razor and any grooming plans.
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby malcolmzilla » Wed Jan 03, 2018 9:24 pm

Thanks Axel, was hoping someone with hillbilly lernins would chime in.

From the diagram attached, the lighting is taken off the circuit from the stator to the regulator rectifier, but perhaps that’s how the regulator works, bleeds off excess voltage on the input? I didn’t rev it out to the limiter with it being a cold start and in the garage maybe that’s why I only saw 11.8 VAC.

Oh and my recti”fire” is behind the mask ready for a gorilla pull quick release in event of trailside bbq action. :D

Rectum? It nearly killed ‘em.
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1DD6EAB6-5F58-4784-8108-DB00100CB87C.jpeg
15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby Rider Eh! » Thu Jan 04, 2018 7:52 am

Running LED's at lower voltage is no problem, they are current driven devices. The more current, the more light emitted. Running them too high on the other hand will burn them out quick. It's best to have a stable 12V as this will allow the max power (or in this case birghtness). There is a minimum voltage an LED requires to fire.

One of the reasons LED's don't work on old dimmers is as old style house dimmers run by decreasing voltage. When you start turning the dimmer down they just shut off, as LED's are basically a diode, and not receiving enough voltage to fire at this point.

Anyways, Alex is right in that the rectifier needs to be run after (in series) with the stock regulator.
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby malcolmzilla » Thu Jan 04, 2018 3:29 pm

Found this diagram (from TrailTech) of typical regulated motorcycle stator AC circuit, and this is how the KTM is wired (see above), so I'd deduce that the KTM AC lighting circuit is regulated AC (~12V), but not rectified, given the factory use of AC lighting.

How it works I don't know, magnets or magic maybe, but I'll take it. :D
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AC circuit.JPG
15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
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Re: Penny Tech (TM) - KTM AC lighting circuit - cheap DC power

Postby axel99 » Fri Jan 05, 2018 6:35 pm

Yep, you are tied into a regulated circuit. For sure the regulator acts as a sink to ground. All good my friends. If ever have a need to dim a led you must use a technique know as PWM( pulse width modulation) and it requires some electronics to work. It also used a lot in the 7.3 power strokes to regulate various high pressure systems. Simple concept and not that hard of a circuit to build if you need it.
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