Kiwi_Roy Posted January 21, 2012 Share Posted January 21, 2012 Hi, I recently pulled apart one of the Bosch starters to compare it with a Valeo. The Bosch has a series wound motor with a direct drive (no gearbox). A series motor can generate very high torque. The Valeo has a motor with permanent magnet fields and a planetary gearbox to increase the available torque. The solenoids on both starters are similar, they both have dual coils and require a really good circuit from the battery to pull in. The bike wiring schematics do not show the dual coil arrangement, it's more like a black box. The solenoid draws a very heavy current for a fraction of a second, If there is too much resistance in the circuit the it will not be able to pull in and close the main contacts. The battery - fuse - relay - solenoid circuit I have shown is about as simple as it gets. For those of you that have the solenoid powered through the ignition switch I strongly suggest you consider re-wiring to bypass the switch. Running the start relay coil through ignition switch is OK, it only draws a fraction of an Amp You will notice I show a 15 Amp fuse in a circuit drawing up to 50 Amp, the fuse won't blow because the peak current only flows for about 1/10 of a second, just until the main contact closes. Bosch Starter.pdf Valeo Starter.pdf I hope this helps Roy Link to comment Share on other sites More sharing options...
Chuck Posted January 22, 2012 Share Posted January 22, 2012 More good stuff.. Thanks! Link to comment Share on other sites More sharing options...
dark_bike Posted February 9, 2012 Share Posted February 9, 2012 Hi Roy, seems I have to add further wires then. <_> what are the respective advantages of these starters? Is the valeo easier on the battery? the bosch better at bringing unwilling engines to life? tom Link to comment Share on other sites More sharing options...
Kiwi_Roy Posted February 12, 2012 Author Share Posted February 12, 2012 Hi Roy, seems I have to add further wires then. <_> what are the respective advantages of these starters? Is the valeo easier on the battery? the bosch better at bringing unwilling engines to life? tom I don't know which is best, I think the Bosch should spin the engine faster, it looks like it will draw a lot more current. Series motors used to be used for traction applications such as electric locomotives, they have a wide speed range whereas a shunt motor (read Valeo) quickly runs out of torque at speed. The Bosch certainly looks a lot beefier. I know some owners have switched from Valeo to Bosch and probably the other way. I have also heard the Chinese Valeo have some issues but I haven't any experience with those. I suspect others have switched instead of fixing the root cause, bad solenoid circuit wiring (see note 1 on my sketches). These days series motors have been replaced by 3 phase AC motors with Variable Frequency Drives for traction, perhaps one day we will see this type in a Guzzi starter, I was really surprised to see a permanent magnet Valeo. Perhaps Guzzi will come out with an electric drive train, who knows? Link to comment Share on other sites More sharing options...
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