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I presently have a 12v AC setup on my GP and I want to change it to DC. I have bought the Sootronics DC stator, DC CDI and will get a wassel and battery. Currently I'm using a Broadhurst simplified AC wiring loom and AC ignition switch. Has anyone else done this and if so, how? and what else do I need to get before I start? Also can you get the SIP Speedo to work with DC power?

Dc horn also i’m Currently having a bash at it myself.
Decent link below
https://www.lambrettaspares.com/pages/d ... 0looms.pdf

ULC Soulagent wrote:Dc horn also i’m Currently having a bash at it myself.
Decent link below
https://www.lambrettaspares.com/pages/d ... 0looms.pdf

Thanks for the wiring diagrams.

Muttleyoo7 wrote:I presently have a 12v AC setup on my GP and I want to change it to DC. I have bought the Sootronics DC stator, DC CDI and will get a wassel and battery. Currently I'm using a Broadhurst simplified AC wiring loom and AC ignition switch. Has anyone else done this and if so, how? and what else do I need to get before I start? Also can you get the SIP Speedo to work with DC power?

The MB diagram is fine for a standard 12v DC Wassel conversion but you are using one of Anthony Tams DC Ignitions so the wiring will be slightly different, hopefully Ant will have supplied a wiring diagram with it?

Re the SIP speedo, its the rev counter feed that has caused problems for users in the past as it needs an AC pulse. I connected mine to one of the yellows from the stator and it works just fine, over 2k miles and still going strong

Bit confused by the MB diagram tbh, why 3 batteries? I could understand if they are only very small ones but then one of them says 'battery tray'. The other thing is the fuse should ideally be in the negative leg as otherwise, if something shorts across the battery terminals, the fuse would not blow. Also, 15 to 20 amps is way too high, you wiring will melt with much more than 7 or 8 amps and then combust....I speak from experience

On the MB drawings I think Mark is showing the battery in 3 different positions and you just select the part of the drawing where your battery is fitted. I had the MB loom for a sample and I asked Mark why there is 3 separate DC points and he said it's so you don't have to modify the loom if you decide to put the battery in any of those 3 places. So he's covered all the options. Regarding fuse choice for the main fuse. The rule of thumb is choose one that's 50% above what your stator amperage can kick out. Most standard stators will kick out approximately 8 amps. So I would use a standard 15 amps. If you get a short anywhere on your DC battery line it will blow the fuse as a battery can supply several 100 amps short circuit.

Anthony Tambs wrote:On the MB drawings I think Mark is showing the battery in 3 different positions and you just select the part of the drawing where your battery is fitted. I had the MB loom for a sample and I asked Mark why there is 3 separate DC points and he said it's so you don't have to modify the loom if you decide to put the battery in any of those 3 places. So he's covered all the options. Regarding fuse choice for the main fuse. The rule of thumb is choose one that's 50% above what your stator amperage can kick out. Most standard stators will kick out approximately 8 amps. So I would use a standard 15 amps. If you get a short anywhere on your DC battery line it will blow the fuse as a battery can supply several 100 amps short circuit.

Welcome to the forum Ant, good to see you on here at last Re the fuse rating, I'm not so sure that that 'rule of thumb' really applies. I have a 15 amp fuse in mine but on the way back from the Derby 150 last year, a spare gear cable inner that I'd dropped into my legshield tool box must have shifted and managed to short out the terminals on the USB charger. I only realised there was something amiss as I pulled into a garage forecourt and smoke started billowing from the headset and tool box. I oped the toolbox door and flames erupted. Panel off and ripped the wires off the battery band patted the flames out in the tool box which was actually the wires to the USB. I was VERY lucky it happened where it did and the drama was over in about a minute or so. The wires on the battery were all melted too as were some in the headset but the fuse was still intact.

15 amps on the negative side of the battery will just protect the battery as there is nothing else on the scooter or any accessories that will take anything like that current. A better idea would be to keep the 15 amp fuse but run a heavier gauge of wire to a fuse block with much lower rated fuses for accessories (3 or 5 amps?) and maybe 10 amps for the lighting/horn?. I know that is what I'll be doing when I get round to it.

coaster wrote:

Anthony Tambs wrote:15 amps on the negative side of the battery will just protect the battery as there is nothing else on the scooter or any accessories that will take anything like that current. A better idea would be to keep the 15 amp fuse but run a heavier gauge of wire to a fuse block with much lower rated fuses for accessories (3 or 5 amps?) and maybe 10 amps for the lighting/horn?. I know that is what I'll be doing when I get round to it.

This is how I run feeds off my battery as seen here... http://www.ilambretta.co.uk/forum/viewtopic.php?f=10&t=9550&p=83061#p83061... I'm not sure what use a fuse on the battery side actually is...?!

Feersum Injun wrote:..................I'm not sure what use a fuse on the battery side actually is...?!

If you mean on the negative side? I had to ask the same question a while back and the reason is to protect the battery. depending on how you battery is installed, there can be a possibility of the terminals being bridged and if that happens, no fuses on the positive side will be any help at all So, put an inline fuse at the rating that Ant suggested (15amps) on the negative side of the battery and your fuse block on the positive side will protect the individual circuits.

No, sorry I meant having a fuse from the live feed into the fuse box. I only know the basics when it comes to electrics but would a fuse on the negative side do anything? Is it not just the earth?? I've never seen one shown on any diagram such as the MB one.... I guess by being bridged you mean a screw driver rattling around in the tool box!!! It's easy enough to put one in for 'belts and braces' though...

15A fuse rating is just too much as Coaster found out
Lambretta wiring harnesses made from the cheapest quality cable, Crappy compression Bullet connectors, iffy riveted electrical joints, Age, and Corrosion all introduce an element of resistance along which this current is trying to pass through. Fused at 15A and something has gotta give if this level of current is sustained for more than just a few seconds. You only need a total resistance of 0.8 ohms to draw this level of current.
The fuse, by design is there to protect the wiring from causing a fire. An 8 Amp fuse would satisfy any standard arrangement permitting 96 watts of power which is just a little more than most magneto generators can kick out anyway.

Fast n Furious wrote:..... would a fuse on the negative side do anything? Is it not just the earth?? I've never seen one shown on any diagram such as the MB one.......

The earth carries all the current, same as the positive. If you already have individual fuses on the positive side then I would definitely move your main fuse to the negative leg using NF's suggested 8 amp fuse.

Actually....... That was Feersum Injun that made that quote Coaster.