Lights, capacitors, action.

[The Vandal]

I’m working through the problems on the 1955 g3ls I bought recently and currently perplexing me is the electrics.

The battery was goosed when I got it so I’ve replaced it with a 63v 6800uf capacitor (battery leads screwed directly to the terminals on the capacitor) which I read elsewhere would act as a battery eliminator but things aren’t going quite to plan.

Tick over is insufficient to power the lights or horn, lifting the revs will illuminate the lights but still no horn.

Once underway the lights and horn will work but coming to a stop eg at traffic lights and returning to idle the headlight goes out and won’t re-illuminate until the switch is turned off and back on again.

The ammeter generally sits at (around) +4 regardless of whether the lights are on or not but drops as the revs rise. This sends counter intuitive as wouldn’t more revs mean more power being produced?

I measured the voltage across the battery leads/terminals on the capacitor and tickover was producing +/- 4.5v which rose to around 7v as I lifted the revs so I think that means the bike is producing enough charge right?

Anyone have experience of making their own battery eliminator? Should I just stick another battery in it?

[dave16mct]

I don't know anyone who has fitted a capacitor to a dynamo system. Maybe Groily can shed some light on the problem? I usually fit these to a bike with a dynamo. Ebay number: 154197466225
Dave.

[SPRIDDLER]

Anyone have experience of making their own battery eliminator? Should I just stick another battery in it?

Yes. Fit a battery.
The self-energising magneto provides the ignition.
I've not tried to fit an eliminator but have had the same 6v 5Ah Cyclon battery as Dave for 12 years and it fits in the original battery carrier.

2019-11-20 Burlen 6V 5Ah battery 009 (640x480).jpg

Tick over is insufficient to power the lights or horn, lifting the revs will illuminate the lights but still no horn.

The horn and the Stop light are normally wired directly to the battery. When engine slows the dynamo output will drop to around 4.5v to 5v at which point the cut-out in the regulator will disconnect the dynamo from the battery (your capacitor), otherwise the battery at 6 or more volts will try to drive the dynamo.
The output of a perfect condition E3L dynamo on a good day will be 42 watts (7 amps) at around 2250 rpm (35 - 40 mph in top gear). On tickover with a dynamo in top condition the output is barely sufficient for the demand of your lights which is why a battery is needed as a bulk power 'reservoir'. Ignoring the inevitable wiring losses your headlight alone will be looking for at least 30 watts (5 amps).

The ammeter generally sits at (around) +4 regardless of whether the lights are on or not but drops as the revs rise. This sends counter intuitive as wouldn’t more revs mean more power being produced?

Are your ammeter and capacitor connections the right way round vis-a-vis polarity? I believe that most capacitors are polarised.

I measured the voltage across the battery leads/terminals on the capacitor and tickover was producing +/- 4.5v which rose to around 7v as I lifted the revs so I think that means the bike is producing enough charge right?

Possibly, but voltage is only half the equation; you need current (amps) as well as voltage to produce watts. Ideally you need to check the dynamo power output (watts) with a load which you can do by connecting D&F on the dynamo together and taking a wire from that connecting bridge to Earth via a load. I fudged up the bit of kit below to test with. I used a 12v bulb (the load) on a 6v system because as the engine is speeded up the unregulated voltage will (should) quickly rise to 20 volts or more. A 12v bulb is less likely to blow and should light brightly at just above tickover revs.

Dynamo test rig (640x480).jpg

Link (640x407).jpg

[The Vandal]

Yes. Fit a battery.
The self-energising magneto provides the ignition.
I've not tried to fit an eliminator but have had the same 6v 5Ah Cyclon battery as Dave for 12 years and it fits in the original battery carrier.

I don't know anyone who has fitted a capacitor to a dynamo system.

Ok, maybe I've gotten my wires crossed (haha!) about this battery eliminator/capacitor business. Thinking about it, it might have been more in the context of newer stuff.

I suppose the likes of the pre65 trials bikes don't run any lights so don't need the dynamo or battery or eliminator eh?

Annoyingly I don't have the original battery box, it was a modern(ish) Yuasa that was fitted when I got it, padded out with bits of foam and rubber and held in place with a strap from a Yamaha!

Guess I can strap that Hawker battery in there as it is and pick up a box at some point.

The horn and the Stop light are normally wired directly to the battery. When engine slows the dynamo output will drop to around 4.5v to 5v at which point the cut-out in the regulator will disconnect the dynamo from the battery (your capacitor), otherwise the battery at 6 or more volts will try to drive the dynamo.
The output of a perfect condition E3L dynamo on a good day will be 42 watts (7 amps) at around 2250 rpm (35 - 40 mph in top gear). On tickover with a dynamo in top condition the output is barely sufficient for the demand of your lights which is why a battery is needed as a bulk power 'reservoir'. Ignoring the inevitable wiring losses your headlight alone will be looking for at least 30 watts (5 amps).

That makes sense.

The reg is actually a non standard item too being a modern Dyno Tec DTR100.

Are your ammeter and capacitor connections the right way round vis-a-vis polarity? I believe that most capacitors are polarised.

The capacitor yes, well, I went by the red/black colouration of the leads. I don't honestly remember which way around the leads were connected to the battery but I certainly don't remember thinking anything was amiss with it so...

The ammeter though...I haven't messed with that wiring yet though so lets assume that it is!

I fudged up the bit of kit below to test with. I used a 12v bulb (the load) on a 6v system because as the engine is speeded up the unregulated voltage will (should) quickly rise to 20 volts or more. A 12v bulb is less likely to blow and should light brightly at just above tickover revs.

Dynamo test rig (640x480).jpg

Link (640x407).jpg

Think I'll try a replacing the cap with an actual battery (which is probably a good idea anyway given how everyone tells me the cap is going to send me across the room if I look at it wrong) but thanks for the pic of this, will be useful if I need to make one up.

[The Vandal]

Oh, I happened to be inside the headlamp nacelle looking at the speedo (other issues) and noticed some fabric wrapped wiring in there but the rest is plastic insulated and wrapped in quite a lot of insulating tape so I suspect it's been redone at some point (v5 shows registration date in the '80s so might have been restored then) so who knows how well it was done!

[SPRIDDLER]

Hmm, just a few variables there, then.
I didn't have a battery in the 60's on my Greeves scrambler but it had 'Capacitor Discharge' ignition. I know little about capacitors but I think they have a very small storage capacity and are intended for short bursts of high voltage rather than the capacity to deliver the extended periods of discharge which is available from a battery. For example, when in town with the lights on and the dynamo output drops below the cut-off voltage of the regulator the dynamo power for the lights will be 'switched' by the regulator to draw the power for the lights from the battery.
A dynamo (unlike alternators) generally needs voltage from a battery to energise/magnetise the field coils before it will function although there can be just enough residual magnetism in the field coils to generate an output to the battery.
A Google search doesn't find any info on the Dyno Tec DTR100 or even Dyno Tec at all. Most modern electronic regulators are polarity sensitive and will be marked for which polarity it has been set up. Connecting with the wrong polarity (even instantaneously) can irrevocably damage them so you must ensure that you connect the battery correctly.
Can you not tell from the wires how they were connected to the battery and which one is Pos? E.g. by type/size/method of terminations? Normally your red wire would be Pos and the black one, Neg.

I think that if you are going to get it sorted and can't be sure which battery lead is Neg and which is Pos you need to determine the polarity of the regulator first then connect the battery to match it. I'm assuming it was working before you removed the battery and still is after your capacitor experiment. If the regulator is marked 'Positive earth' the 'E' terminal on it will be connected to the bike frame (the Earth). If it's marked 'Negative earth' the negative will be connected to the frame. Whichever it is then the corresponding battery lead will also need to be connected to the frame. You will see it in the wiring diagram on page 84 here:

http://archives.jampot.dk/book/Owners_m ... Manual.pdf

You could connect the battery and without running the engine, observe the ammeter with the lights on. If the ammeter shows a Discharge the battery is correctly connected. If it shows a Charge the battery wires are on the battery the wrong way around. This assumes that the ammeter was correctly connected in the first place. HOWEVER, and I can't say for certain as it depends upon the regulator design but connecting the battery the 'wrong' way round to carry out this test may terminally damage the (relatively expensive) regulator.

Since the bike is new to you I (we) can only assume ( ) that the system was working correctly before you replaced the battery with the capacitor in which case the dynamo output would already have been polarised the same as the regulator.

And finally ............if it hasn't one already, (and bearing mind your comment about the iffy taped-up wiring) fit a fuse in one of the battery leads. I run with a 10 amp fuse but a 15 amp would be O.K.

Apologies for the long-winded reply but I (we) don't know what we don't know.
(I'll re-read this ramble in case I've lost the plot somewhere).

[The Vandal]

I know, it's a lot of assumptions.

I'm thinking/hoping that if the battery had been hooked up black to +ve and red to -ve I'd have noticed so I think it was connected correctly when I got it.

I've looked through some photos I've snapped on my phone and the reg says +ve earth on it and I can see the red wire being screwed to the battery box (which I presume in turn earths to the frame etc) so that looks good.



I wonder if as well as switching to draw the lighting power from the battery when the revs drop too low, could my regulator be doing similar when revs get too high as some sort of protection and that's why I see the ammeter drop to a discharge?

[SPRIDDLER]

I've looked through some photos I've snapped on my phone and the reg says +ve earth on it and I can see the red wire being screwed to the battery box (which I presume in turn earths to the frame etc) so that looks good.

Yes, that fine. Positive Earth. But I'd prefer the battery Pos (the Earth lead) to go straight to a clean fixing/bolt on the frame rather than to the battery case which one hopes has a good electrical connection to the frame. EDIT - It seems there is a red wire from the red Pos lead at the bolt on the box going off somewhere which may be to the frame.............
I notice that the label says it's a 12v regulator. I've never used a 12v regulator on a 6v battery/ 6v dynamo system which I assume you have as you mentioned somewhere that you measured 7v output from the dynamo.

I wonder if as well as switching to draw the lighting power from the battery when the revs drop too low, could my regulator be doing similar when revs get too high as some sort of protection and that's why I see the ammeter drop to a discharge?

The regulator will regulate the output of the dynamo (regardless of how high are the revs) to match the requirement of whatever items of electrical equipment are switched on at the time. The ammeter indicates the current going into or out of the battery. When the battery is fully charged the ammeter reading should ideally read neither charge nor discharge but today's ammeters are pretty cheap and nasty instruments so the reading on it cannot be taken as totally accurate to one or two amps but more as a guide. Provided that with the lights on at around 35 to 40 in top the needle sits at zero or just on the charge side the regulator is doing its job. If the battery is in need of some charge the regulator will sense this and increase the dynamo output and the ammeter reading may go up to 5 or 6 amps, but it will drop back when the battery becomes fully charged.

An off-the-wall thought ......If the ammeter drops to show a discharge at high revs, particularly with the lights on it's possible that vibration is disturbing/interrupting/shorting a connection in the wiring or causing the dynamo brushes to only make intermittent contact with the armature...........

[The Vandal]

Yes, that fine. Positive Earth. But I'd prefer the battery Pos (the Earth lead) to go straight to a clean fixing/bolt on the frame rather than to the battery case which one hopes has a good electrical connection to the frame. EDIT - It seems there is a red wire from the red Pos lead at the bolt on the box going off somewhere which may be to the frame.............

So the bolt in the battery case, might need to check this but I think the lead going up goes to the back of the reg, the one going down is the the one with the battery terminal.

I notice that the label says it's a 12v regulator. I've never used a 12v regulator on a 6v battery/ 6v dynamo system which I assume you have as you mentioned somewhere that you measured 7v output from the dynamo.

Hidden behind some of the wiring it says "6 and"... 12volt then the writing underneath has instructions on how to wire it for 6v and for 12v. It says '12v - brown only to ammeter' and '6v - orange linked to brown' and it does look like the orange and brown get linked then become purple/black.

An off-the-wall thought ......If the ammeter drops to show a discharge at high revs, particularly with the lights on it's possible that vibration is disturbing/interrupting/shorting a connection in the wiring or causing the dynamo brushes to only make intermittent contact with the armature...........

A short is definitely a possibility. My first time riding it it did conk out randomly a couple times. I put it down to my inexperience and I was being distracted by a particularly terrible bmw driver infront of me but it could have been a short. I haven't experienced that since but I have moved the wring in the battery case around a bit and I've had the tank on and off messing with the throttle cable and carb so it could just be that I've moved the wiring around.

I've ordered one of the Hawker batteries, hope I still have a charger somewhere. Definitely have an Optimate maybe that'll work.

[Groily]

I don't know anyone who has fitted a capacitor to a dynamo system. Maybe Groily can shed some light on the problem? I usually fit these to a bike with a dynamo. Ebay number: 154197466225
Dave.

Fraid I can't - never tried on a dyn bike, and have ditched as a rule on alternator ones. A battery for choice, with a modern regulator or rect/reg with alternators. On the P11 etc the capacitor was there to provide batteryless starting with coil ignition, but I have never really trusted it ! Not a reservoir for lighting power, for sure.
Depending on type of reg fitted, dyn bikes can run lights with no battery above certain revs only but flickery and no good at tickover. LEDs help though, if fitted. Alt ones have more juice at lower revs. But it's all a bit unnecessary really, as batteries aren't hard to find!