Electrical Idiot Alert

[pauLI]

As the title says, I am an electrical idiot so here goes
I currently have a standard 6v battery model GT200 and *I would like to do* the 12v dc conversion
could one of you lovely chaps please list out the items I would need to purchase to do this
I would like to be able to run pathfinders and have a charging point for phone etc

my only other requirement is to keep the standard looks if possible so have all the additions hidden away

thanks in advance


*like I'm going to do it, more chance of me scaling Everest in me pants*

[Captain Pugwash]

Are you keeping it points or going electronic.
GT engine is low revving so points should work just as well as any electronic.

[Digger]

What the Captain said - nothing wrong with the 6v DC system.

[pauLI]

Thanks for the reply
If the 6v is good enough then that is what it will be
so what would I need to buy/change to do this plus run the bits I would like too

[Captain Pugwash]

The points system works well on low revving engines and IMO proves more reliable than most aftermarket electronic kits.

But you can convert the existing stator and lighting to 12volt DC.

My advice is if you do and your still running a brass flywheel then you would be best to fit early type lighting coils with the thinner wire because these are already wound with more windings to suit.

I've converted a few GT 200 points systems to run on 12v DC and they never work as well if you fit the later type Italian lighting coils as fitted to die cast flywheel systems. If you fit the wrong coils or wind with too thick a wire using a brass type 6 pole flywheel then the battery doesn't hold its charge as well during town riding due to its poor charging at low revs.

To covert the stator it needs two lighting coils swapping out and then the wiring between the four lighting coils alerting.

[grandpa]

Hi PauLI
Have a look at this RS wiring diagram
http://scootrs.com/tech.cfm?tip=12volt
Remember your stator might only produce about 80 watt. If you have your headlight on say 35 watts plus rear light 5w that's half of your output .Press the brake pedal
23w and you wont have much left for your pathfinders.However a 12v 5amp/hr battery will give you another 60watts( watts = volts x amps)
I found the 12v dc wassell conversion works well.
It will be a compromise as the Lambretta was never designed to power satnavs and pathfinders... you got by with a map and dim lights
As I have mentioned in other posts ..... a battery will keep the lights on if you have to push your machine home in the dark
grandpa

[kennystag]

I think the Lambretta was designed to keep breaking down, pushing it home was ok when we where 16,not when your getting on a bit, I think we all want reliability, so how do we do that with a Lambretta that we all love for all there faults.
Cheers
Stag

[tv175lambretta]

Another viewpont...Converting to 12 volt means that only half the current is needed to achieve the same power output in light bulbs. That in turn means that the voltage drop over bad electrical connections is only half as much, and the power lost in bad connections is only a quarter as much. Bad electrical connections in my experience are the cause of so many lambretta electrical problems. Having said all of that, put your effort into improving the electrical connections (particularly earth return connections) and 6v will be fine

[Andyf]

ain't volt-drop a quadratic equation?

(like I've got a frkin clue )

[Captain Pugwash]

ain't volt-drop a quadratic equation?

(like I've got a frkin clue )

The voltage at the beginning of the circuit is full voltage (whatever that is) but that voltage has dropped at the end of the circuit (at The Bulbs) due to bad connections (electrical resistance)
There is more voltage ( 12v ) available so less voltage drop along the circuit to the bulbs, I think that's what's being implied.
We were taught that volts is the force or pressure that pushes the electricity along a circuit, the higher the volts the greater the pressure.
If you think about the ignition spark then the wattage is very low probably no more than 25 watts maximum. But the high voltage gained by using a HT coil to raise the voltage in that circuit to many thousands of Volts and causes a spark to jump through an air gap to make the engine run.
If the voltage was low as it is in a lighting circuit then there would be no ignition spark.

[MK Monty]

https://www.youtube.com/watch?v=J1ho8di4ywQ
Electrickery mumbo jumbo me thinks

[tv175lambretta]

Yes the higher the voltage, the less 'lost' power . That's why long distance power lines are at a very high voltage


For those interested..

watts divided by volts = amps W/v = i
so if a certain wattage (power) is required at the bulb, then the amps (current) in the circuit is only half as much at 12 volts than it is at 6 volts

volts = amps x resistance v=ir
so the voltage drop across a bad connection (resistance) is proportional to the current (which is only half as much at 12v than at 6v)

watts = (amps) x (amps) x resistance W=i^2 r

All of which means with 12v there's more voltage available at the bulb with only half the voltage drop and a quarter of the power loss

The above formulas are just about correct for DC circuits and are more or less true for lambretta ac lighting circuits if you take RMS values for voltage and current. Its actually more complicated as resistance is likely to increase with current, so the power losses at a lower voltage are evem worse.

[Andyf]

so, instead of the loss being 1/2 it's 1/(2^2)? The latter being a vulgar form of 1/4?