CG125 Alternator upgrade?

[TUG]

So the charging system on the CG is a bit pants, anyone who has had one knows this. I want to stick a decent HID lighting kit and an alarm onto my project bike in the future and to do this I need a decent capacity battery and a decent charging system to boot.

What I wanted to know is how difficult it would be to use the alternator from another bike, say, A ybr125 or an YZF R125 which have nice multi stage windings on them and decent sized batteries to suit?

Thanks in advance.
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Haz ER-5, innit!

[AndyCF]

I'd check the wiring diagrams for this first as (its unlikely but its worth a few minutes of your time) you may find that a small mod can improve the charging rate.

For example I know on the C50/C90's etc and also on the Kawa KC's (I did mine) there were two "outputs" from the generator, it only used the "higher output" when the lights were on by default, a simple unplug / plug in to a different connector 'fixed'

I realise we're talking different here but...

I never had any 'over charging' issues with it using the higher output all the time, in fact the lights tended to actually work properly instead.

As I say its very unlikely the CG has this "feature" but I think its probably worth a quick squint at a wiring diagram to be sure, before spending any pennies if there's a suitable 'ready' alternative.

From memory actually Haynes covers this 'tweak' for the KC at least.

My only other thought is, does your bike have an electric boot ? I'd guess the electric start models have a slightly higher generator/alt output than the kick only models, so that would be one other idea if it would fit, to squeeze in the 'electric boot' alternator.

[G]

I'd have thought it's likely the original CG headlight would be 35w and a replacement HID light quite likely the same.

No problem sticking any battery size you can physically fit in there - bigger battery should sort your possible alarm issues.

[smegballs]

My approach would be to get some headroom by replacing the tail/indicator/instrument lights with led equivalent.

Speedo + tacho + rear lights = 15w as usually 5w apiece. LED bulbs can easily get that down to 1-2W giving you at least 10W headroom freed up.

[AndyCF]

[smegballs]

Yeah I have found the cheap Led tail/brake to be shit too, currently running incandescent till I build a proper circuit myself.

The T10s for the pilot and instrument lights have been fine tho, as have the BA15 indicator ones too.

Had one T10 fail quite quickly, but given cheap unbranded Chinese LEDs can't complain too much.

[Teflon-Mike]

What age CG?
What magneto does it have now?

It's unlikely you'll find many more amps from many other small bike genies, they are all pretty restrictive. Original CG's electrics were very basic 6v, points ignition and AC direct lights. Later models got 12v, but still retained AC direct lamps.

That AC-Direct lights, will likely be your main bug-bear trying to upgrade to HID's... amps from genny go straight to the lamps, un-rectified, unregulated, which is pretty efficient for a low power system.. ironically, an HID is an AC lamp, and to run off 12v DC, they have an inverter that re-converts the DC to AC and ramps the volts to something stupid like 12000v to make it 'arc' in the bulb.... would be convenient if you could use the AC direct off the mag, and ramp it like for sparks with a coil... but it's not high enough frequency or stable enough, unfortunately... SO, you will need to isolate the AC direct supply, and get that going to the battery, then take HID supply off that.

Just trying to plug an HID kit into the headlamp bulb plug is likely not to work very well, unfortunately.

Headlamp switch, in the 'off' position, doesn't completely break the AC direct supply to the lamps, but switches feed from the lamps, to the rectifier so unused amps can help charge the battery. SO, you will have to resolve that one too... without pouring over wiring schematics, I think what you have to do is take the feed to the lamp switch from the genny, and bypass the switch so the lighting supply always goes to the regulator, as if 'lights off'. then take the cut feed to the light switch and dog it in off an ignition switched battery supply so that headlamp can have regulated, DC volts.

You will also need to look closely at the tail & brake-lamp wiring, the tail is often on DC supply off the battery, whilst stop is on seperate feed with the AC direct headlamp... which could cause hassles, especially if you try using LED tail lamp bulbs...

THIS is a niggle you will likely have to tackle whatever generator you try and use, regardless of the amps it may bang out..

After that? You are hugely adding to the overall efficiency losses of the system, so anything you may gain, is likely small, if at all.

As G points out, an HID is usually about 35w draw, which is probably no less than the nominal rating of original headlamp bulb.. but unlike a traditional tungsten bulb, the electronics that condition the supply for them, demand stable 12v, and if the volts drop, the lamp will start flickering or stop working alltogether, where a tungsten will just go 'dim' when supply starts to drop... which on AC direct it often will if the tick-over is too low...

Oh-Kay... practical advice.....

I have rewired a few 125's in recent years. Snowie's 125 Super-Dream, with all the 'gadgets' she wanted.. HID, Heated Grips, alarm, phone charger AND SatNav socket, hazard warning lamps!!! Was probably the less challenging. The 125 superdream, benefited from one of the most powerful gennies on a 125, as Honda significantly over rated it for the early e-start, and it didn't have AC direct lights, so it was reasonably straight forward to dog in the toys off an constant live or ignition switched supply as appropriate, tally up the draw, then do a profit and loss account to work out how much needed to be saved to keep it in the black!

35W HID saved I think 10w over stock tungsten bulb in the headlamp.... using an LED in the tail, saved 15 'constant' on the tail, and 25 'occasional' on the stop, which were probably largest single savings to be found. LEDing the indies, saved 21W per corner... but you only use one at a time, and they are only lit half the time when used... switching out the electro-mech flasher unit for an electronic one that isn't load dependent to keep flash rate constant for LED's probably offered as much practical saving. Most significant saving found was probably in the clocks, swapping out. indy, neutral warning, headlamp telltale and backlight bulbs, each 8w otmh, for milliwat LED's.. ditching the backlights saved as more watts as LEDing the tail-lamp!

And guess what? Alarm STILL drained the battery in a couple of days if it wasn't used!!!

The Yammie enduro, was a much more involved, as I had to get 12v out of the thing before I began.. conveniently didn't have much wiring to try and butcher, so I started with a clean sheet and made all from scratch. with a 6v points ignition genny, with an AC direct lighting coil and a zenner rectified 'accerrory' coil; I used a , I think four pin, pit bike reg/rect. two inputs, one output and an earth, I gave one feed to AC direct lighting coil, one to the accessory coil, and put the output straight to the battery... nominally 6v mag, delivered enough over-volts at a slightly high tickover to give a nominal 12v out the reg/rect.. then everything else, including the HID was taken off battery supply.

I used component LED's in the clocks for backlights and tell-tales, LED's in the indies with electronic flasher again; LED'd the tail lamp, and 12v battery... which was pathetically small, and the alarm, on it's own, would flatten in a day and a half...... had to use a partic ularly small capacity battery to actually make space for it..... BUT still

'Lesson' in this is that the 'stand-by' current draw of an alarm, whilst nominally milliwatts, is often quite a few miliwatts, and constant draw, likely to be the biggest user of electric all told.

I have never 'solved' that niggle; seems that the nominal draw is loaded a lot by 'remote' arming radio reciever, constantly 'on' listening for the de-arm fob. I suspect that non remote activated systems, if you can still find one, may have better passive current draw, but how much better that may be, is in question.

Given that, at best, an electronic alarm just acts as a second ignition switch to kill sparks, that's easily bypassed on an 'earth kill' ignition like the CG, and make annoying noise when cats jump on the seat in the night... (hiking current draw and flattening battery even quicker!)... it is an element of 'the plan' I would seriousely question doing again... and pondering whether putting cost and effort into hard security woule be more effective allround.

Onto the lights? No doubt that HID chucks out a LOT of light.... BUT, again, even using 'good' HID kits, with HID main and dip, to actually get full HID benefit and power saving, only any good if its thrown where you want it... and in that, the 'small' lamp shell of the enduro, showed that was a pinch point. Messing with different lamps and lenses, the small lamps, even with HID in them didn't give all the benefit they should or could... same set up in a 7" shell with a decent reflector/lens really showed how much even a 'good' small shell choked the lumins. Using an 'old' reflector/lens, or worse a crappy after-market one, showed just how much more significant to 'good' rather then just 'bright' light those are.... A-N-D conclusion, that, thoroughly renovating 'original' lamps, probably even pretty chitty 6v AC-direct, paying attension to losses in corroded connectors or wires, ditching mottled reflector and or etched lens, NOT using innacurate patern replacement, and making the thing as good as new, CAN be a huge revolation in the light you get from the thing as an audaciouse 'upgrade' like Halogen or HID.. ultimately prove as 'cheap', more reliable, and a darn site less 'hassle' trying to make it work!

I am not so sure, I would bother trying to upgrade lamps on a lightweight again..... or anything else for that matter. I would probably still convince myself to go 12v if it wasn't, but beyond that?

Whilst as said, the alarm is likely to be a lot of hassle for dubiouse practical worth... so all told... I'd be pondering the plan from scratch..

IF that helps....

IF you must upgrade the genny on the CG... how much you may gain, will depend on how much you dont have to start with.... looking for 'more; though, my starting point would NOT be YZF's or YBR's.. but the Chinky CG copy motors. Most are 12v and some I believe are four-coil, three 'charge' plus ignition, most likely to give as much as you can get, AND unlike ignitions for potentially fuel injected bikes, contain the coils and trigger need to power and spark CDi ignition system. also likely to be bolt for bolt interchangeable, if not in the mag cover, then certainly with mag cover from donor system.... BUT, I would still expect to have a lot of 'fun' with the multimeter, trying to graft it into CG wiring, getting power where its wanted and sorting reg/rects, CDi's and switches along the way! A-N-D, I would expect it to actually be less hassle, to simply ditch the CG's oe wires and start from scratch, with a soldering iron, a box full of connectors and a few rolls of coloured cable as I did with both the enduro and in the end snowie's CB! And I can say with some surity, that is NOT a cheap or quick fix... but it IS a whole lot less hassle and probably ultimately 'cheaper' than trying to teach old wires new elec-tricks!!

HTH.... if not... god luck & see you in the asylem, to debate crimps vs solder!!!!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[smegballs]

For all that hassle I'd be tempted to try making a "hid pre-driver" box. Pipe the AC to the headlight region, then put it thru a bridge rectifier to make unregulated DC, then use a buck regulator rated for about 80v input to get the 12V.

I've often thought why aren't people using the cheap and readily available switchmode regulators, to run 12v headlights in old shit 6v bikes.

This fella looks good for the job

https://www.linear.com/solutions/1752

[WD Forte]

HID for a CG125?
Are you going to be touring remote regions overnight?
If not, and its just for general running about, I'd look into led options.
Never make anything more complicated than it needs to be

As for the charging system, I'd probably patch in a conventional12v one from a Chinese CG clone bike and rewire the bike to suit
(Its a CG, hardly rocket science right?) and use leds in place of incandescent blubs
You're not going to suddenly get 200W+ out of a stator upgrade but
may get say 60-70W if you're lucky

Battery: you may well find a Li-Ion type that will fit into the same space as the original that will have much more capacity,
But a good quality conventional type may well do if useage is managed.
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bikers smell of wee

[redeem ouzzer]

Personally I'd be simplifying the wiring. No battery (or a big capacitor), lights on and off and a Killswitch is all you need. Keep it light.
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Be a REAL MAN!

[G]