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

New Bikes, Old Bikes, Bike Setup, Bike Mods, Questions, Riding Technique, Advice.
User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

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- ... 2749.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
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

User avatar
AJRJ
2024 RMDRA Member
2024 RMDRA Member
Posts: 1187
Joined: Sat Jun 26, 2010 1:45 pm

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

Post by AJRJ »

Nice job!

User avatar
Rider Eh!
2024 RMDRA Member
2024 RMDRA Member
Posts: 726
Joined: Sat May 26, 2007 7:18 am
Location: Calgary

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

Post by Rider Eh! »

Link to thumpertalk post? I may do this...
'18 300 XC
'02 XR650R

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

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 ... -regulator
Being an enginerd, hoping you will translate this electropixiespeak for us luddites. :D :cheers:
15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

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

User avatar
dirtyboy
2024 RMDRA Member
2024 RMDRA Member
Posts: 6971
Joined: Sat Dec 11, 2004 5:04 pm
Location: Calgary, AB
Contact:

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

Post by dirtyboy »

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

User avatar
axel99
2024 RMDRA Member
2024 RMDRA Member
Posts: 1277
Joined: Fri May 26, 2006 9:06 am
Location: Scouting 2017 Dirtier Moose

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

Post by axel99 »

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.
#Z3B

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

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.
Attachments
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...

User avatar
Rider Eh!
2024 RMDRA Member
2024 RMDRA Member
Posts: 726
Joined: Sat May 26, 2007 7:18 am
Location: Calgary

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

Post by Rider Eh! »

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.
'18 300 XC
'02 XR650R

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

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

User avatar
axel99
2024 RMDRA Member
2024 RMDRA Member
Posts: 1277
Joined: Fri May 26, 2006 9:06 am
Location: Scouting 2017 Dirtier Moose

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

Post by axel99 »

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.
#Z3B

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

Folks have asked for a wiring diagram. Here’s an attempt.
7C71A812-5AFB-42A8-9959-A8076678E6BA.jpeg
15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

User avatar
Rider Eh!
2024 RMDRA Member
2024 RMDRA Member
Posts: 726
Joined: Sat May 26, 2007 7:18 am
Location: Calgary

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

Post by Rider Eh! »

Thought I'd add some more to this as I think I may do the same here shortly.

You can also tap into parallel on the output of the Rectifier and run a 30,000 to 50,000 uF capacitor in order to smooth the DC voltage. I think I may have one at home actually and may try this, otherwise you should be able to pick one up at MRO Electronics south of the airport.

There's a lot of good reading here:

http://ktmtalk.com/showthread.php?39336 ... -Tutorial)

http://ktmtalk.com/showthread.php?47967 ... he-Sequel)

The only thing I can't figure out is the ground, Malcolm did you use the brown wire as the input to the eBay rectifier? This seems strange as it should be grounded to chassis.
'18 300 XC
'02 XR650R

User avatar
malcolmzilla
2024 RMDRA Member
2024 RMDRA Member
Posts: 879
Joined: Fri Jun 26, 2009 11:14 am

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

Post by malcolmzilla »

Behind the mask there's a pair of wires that go the the stock headlight connector, I adapted spade terminal into those to the rectifier input, offhand can't recall the colors. It would make send one side is ground tho. You have to jumper or close the circuit at the headlight switch terminal too.
15 Yamaha YZ250FX, 270cc, cams
15 XC250
11 Berg 570, dualsport and supermoto
17 PW50
78ish CT70
Just another Dirt Donkey...

User avatar
Rider Eh!
2024 RMDRA Member
2024 RMDRA Member
Posts: 726
Joined: Sat May 26, 2007 7:18 am
Location: Calgary

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

Post by Rider Eh! »

I have found a few alternate rectifiers which you can buy locally at MRO which will perform the same.

http://www.mroelectronics.com/mro/produ ... oduct=5999
http://www.mroelectronics.com/mro/produ ... oduct=5947

You can also find these on eBay, Amazon etc.

I also contacted the guy who supplied Malcolm's to see if he would make in 5 amp or 10 amp, he said he was going to try a few and test them to see if they needed heat sinks.
'18 300 XC
'02 XR650R

Post Reply