CameronMac Posted January 11, 2010 Share Posted January 11, 2010 I'm very new to bikes and I have a ton of questions on how exactly everything works, but whats really getting me stumped is the electrical system. So here's my list and I know some of them are probably very obvious so bear with me. - What does a Magneto do? - Can my DT175 run without a battery? - Hmf guess that's about it Link to comment Share on other sites More sharing options...
little dave Posted January 11, 2010 Share Posted January 11, 2010 I'm very new to bikes and I have a ton of questions on how exactly everything works, but whats really getting me stumped is the electrical system. So here's my list and I know some of them are probably very obvious so bear with me. - What does a Magneto do? - Can my DT175 run without a battery? - Hmf guess that's about it the magneto creates electrical current (a/c) by passing magnets attached to the flywheel past a copper coil. that current is then sent to the rectifier diode which converts the a/c into D/c current which is used to run the lights and charge the battery. its also responsible for creating the spark, when used with an ignition coil. yes a dt can run without a battery, but the battery acts as a "soak" to absorb residual current. so if you take out teh battery you will blow all your bulbs. again and again. the headlight runs off of an a/c circuit, and is wired separately. but its also affected by the lack of a battery. whats your situation? why do you want to eliminate the battery? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 11, 2010 Moderator Share Posted January 11, 2010 the magneto creates electrical current (a/c) by passing magnets attached to the flywheel past a copper coil. that current is then sent to the rectifier diode which converts the a/c into D/c current which is used to run the lights and charge the battery. its also responsible for creating the spark, when used with an ignition coil. yes a dt can run without a battery, but the battery acts as a "soak" to absorb residual current. so if you take out teh battery you will blow all your bulbs. again and again. the headlight runs off of an a/c circuit, and is wired separately. but its also affected by the lack of a battery. whats your situation? why do you want to eliminate the battery? The ignition system on DT125/175 runs totally separate to the battery. The battery is there as a reserve to light the idiot lights when the ig is switched on ( confusingly in this case) and the parking light when the engine is off, it doesent do a lot else. Apart from feeding the indicators. The ig switch (this varies between models and markets) or / and bar switches switch the charging and lighting coils output depending which is required, if the lights are on the battery doesent charge as the feed goes to the lighting circuit and rectified with the regulator bleeding off any surplus, if the lights are off the rectified voltage goes to the battery with the regulator tapping off the excess. If you want to run without a battery then you will have to run permanant lights or you will cook the regulator, and running permanant lights WILL cost you headlight bulbs as the spike from starting the motor can, (i've done it often enough) blow the headlight. Or obviously you could remove the charging/ lighting circuitry altogether and just run an ignition loom like a Motocross bike. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 11, 2010 Moderator Share Posted January 11, 2010 - What does a Magneto do? It charges the battery, lights the lights and provides the ignition power - Can my DT175 run without a battery? Yes it can, as a field bike but not a fully fledged road going bike, here in the UK you may get away with it if you can get a 'Daytime' MOT test like trials bikes and the like have - Hmf guess that's about it Link to comment Share on other sites More sharing options...
Speedshop Posted January 11, 2010 Share Posted January 11, 2010 Ok, bit of confusion here. A magneto is a mechanical device that makes high tension sparks at a specified point in the crank's rotation without the need of a battery or any other external power source. Its a very old term, but it does apply to any system where it is self generating, IE its just the engine rotation required to produce a spark. Normally this is applied to a system that uses a set of points to time the spark, but you can equally apply the term 'magneto' to many basic CDi systems. Where it gets a bit confusing is that CHARGING coils to provide power for the lights and battery are often included within the same generator. To use the old terms this set up would be called a magdyno (magneto +dynamo). The two systems are completely separate and on older machines they would have been two separate units bolted on the engine. You can indeed run batteryless, but you must connect a capacitor where the battery went. If you don't you risk damaging the generator/regulator/wiring loom. You'll need an electrolytic 48v , 10,000uF (or there abouts) capacitor. Look for one that has 'switched mode capability'. All this means it that it will last much longer as it is resistant to constantly changing loads or spikes in the system. Link to comment Share on other sites More sharing options...
CameronMac Posted January 11, 2010 Author Share Posted January 11, 2010 Great, this cleared up exactly what I was wondering. I bought a tail bike with hopes of restoring it to it's former glory and they guy who last owned it told me he had it ran over the summer. But when I looked I noticed there was no battery and being a car guy I got confused. I was also wondering if starting it up before I got a battery for it would hurt anything. Seeing as the only light still attached to it is the headlight which (surprise) is burnt out, I at least won't have to worry about burning out any lights Thanks for all the helpful info. Link to comment Share on other sites More sharing options...
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