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Title: Anyone know around how many amps the starter relay uses? Post by: Drunken Monkey on March 25, 2009, 12:59:24 PM Not the amps FROM the relay (answer: a buttload) but rather how many amps it takes to actuate the relay in the first place.
I'm looking to replace my handlebar controls with some tiny ones, with tiny (~20 gauge) wires and I'm just curious if it can handle the load. If not I can always wire in a relay, but it seems pretty stupid to use a relay to activate yet another relay. Thanks in advance. Title: Re: Anyone know around how many amps the starter relay uses? Post by: Ducnial on March 25, 2009, 04:05:42 PM Using an ohm meter measure the resistance of the relay coil.
Current(I) = Voltage (E)/Ohm (R) I=E/R R=E/I E:I*R Title: Re: Anyone know around how many amps the starter relay uses? Post by: mitt on March 25, 2009, 04:56:37 PM Using an ohm meter measure the resistance of the relay coil. Current(I) = Voltage (E)/Ohm (R) I=E/R R=E/I E:I*R That should be close enough. If the relay is mechanical, it will change its coil resistance (impedance) as it pulls the plunger. Best bet is to find a part number and look up the specs. mitt Title: Re: Anyone know around how many amps the starter relay uses? Post by: Howie on March 25, 2009, 07:53:46 PM Or crank the bike over with an ammeter connected in series with the small positive wire going to the solenoid, better yet, one with an inductive probe. A meter that will capture the highest reading is best. It will probably take more amperage to pull in the plunger than it will take to hold it. Then add a couple of amps as a safety margin.
Title: Re: Anyone know around how many amps the starter relay uses? Post by: mitt on March 27, 2009, 09:11:12 AM Or crank the bike over with an ammeter connected in series with the small positive wire going to the solenoid, better yet, one with an inductive probe. A meter that will capture the highest reading is best. It will probably take more amperage to pull in the plunger than it will take to hold it. Then add a couple of amps as a safety margin. I don't think an inductive probe will work with a DC current - no alternative current to induce a secondary current. For DC current you need a Hall type sensor probe, or like you said, a meter in series, or a good low resistance shunt (resistor) in series and a volt meter to measure the voltage drop across the shunt. mitt Title: Re: Anyone know around how many amps the starter relay uses? Post by: 64duc on March 27, 2009, 09:33:59 AM I don't think an inductive probe will work with a DC current - no alternative current to induce a secondary current. For DC current you need a Hall type sensor probe, or like you said, a meter in series, or a good low resistance shunt (resistor) in series and a volt meter to measure the voltage drop across the shunt. mitt Or, if you don't have any of these meters, just install an inline fuse holder in series, start with a 5 amp fuse and work down till one blows. Then go back up one size. Poor boy test. Title: Re: Anyone know around how many amps the starter relay uses? Post by: Major Slow on March 27, 2009, 09:44:54 AM Why do need to mount the switch on the handlebar. Do what the choppers do, mount it under the seat or tank. The only time you need to start the bike you are sitting still. It needs to be easily accessed when sitting on the bike in case it kills. No real reason for it to be on the handle bars.
Title: Re: Anyone know around how many amps the starter relay uses? Post by: Langanobob on March 27, 2009, 12:03:43 PM Quote I don't think an inductive probe will work with a DC current - no alternative current to induce a secondary current. For DC current you need a Hall type sensor probe, or like you said, a meter in series, or a good low resistance shunt (resistor) in series and a volt meter to measure the voltage drop across the shunt. Fluke and others sell "Amp Clamp" type meters that will measure both AC and DC. Don't know what the operating principle is for DC mode and it would be interesting to find out. It's probably Hall Effect like you mentioned. They look the same on the outside as a regular AC inductive probe amp meter. Title: Re: Anyone know around how many amps the starter relay uses? Post by: mitt on March 27, 2009, 01:27:26 PM Fluke and others sell "Amp Clamp" type meters that will measure both AC and DC. Don't know what the operating principle is for DC mode and it would be interesting to find out. It's probably Hall Effect like you mentioned. They look the same on the outside as a regular AC inductive probe amp meter. Yes, most Hall sensors are clamp type also. mitt Title: Re: Anyone know around how many amps the starter relay uses? Post by: Drunken Monkey on March 27, 2009, 02:42:06 PM Well, the issue is now moot. I've discovered this:
http://ducatimonsterforum.org/index.php?topic=21115.0 (http://ducatimonsterforum.org/index.php?topic=21115.0) Title: Re: Anyone know around how many amps the starter relay uses? Post by: Howie on March 27, 2009, 09:54:10 PM Fluke and others sell "Amp Clamp" type meters that will measure both AC and DC. Don't know what the operating principle is for DC mode and it would be interesting to find out. It's probably Hall Effect like you mentioned. They look the same on the outside as a regular AC inductive probe amp meter. Not to mention the good ol' Sun VAT 40 dating back to the '70s Title: Re: Anyone know around how many amps the starter relay uses? Post by: Norm on March 28, 2009, 05:02:23 AM I wire bikes from scratch and I use 14g (I think) for the wire from the switch to the relay. So far, none of the magic smoke has escaped.
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