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switched power source


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I am in the early stages of "farkling" my 09 RT, and wondering where is the source for switched power?I am using the "Fuzeblock" which has a built in relay and capability ti set each connection as switched or not. This was easy on my 99 RT, but this different wiring/controller scheme has me a little apprehensive. Also, I tried searching, but didn't see anything that answered my question,so I probably need help using that feature as well.



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On my 08 RT, I have an aftermarket GPS, so the factory GPS connector was open. It's taped to the frame between the instrument cluster and the headlights. I used the GPS power to power a relay that powered my fuse block.

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The other usual sources for trigger wires are

1) Rear accessory outlet wire. Note this is ZFE controlled so has a delay after the key goes off- that is usually 20-30 seconds but can be 20 minutes, sometimes.

2) Front parking light wire

3)My choice, the hgih side of the starter relay coil.


Where do you want the Fuzeblock to go?

Do you want a ZFE shutoff delay or not?


I picked the rear fender under the seat for my fuse panel. Some like the front.


Main thing is do a good job with good connections, protective loom, fuses of proper value, etc etc so you don't fry something expensive. I use a diode in the trigger wire to isolate fuse panel connections from bike wiring (anything with its own relay like a light harness can put a spike back into bike wiring if you don't and becasue BMW doesn't publish computer box circuits, there is no way to know if they have any internal spike protection)




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Hi Nesbocaj


The easy way is to just buy a relay with a clamping diode or clamping resistor already in it. Most small automotive duty Bosch type relays already have high voltage clamping inside the case. Just look on the side of the relay for the diagram of the innards, if it is internally clipped it will have a diode or resistor showing on the little diagram.


As to your question? Most small automotive relays need around 30-50mA to energize. A proper sized clamping diode should be able to handle the forward bias current and be able to handle the reverse spike voltage. Those small relays can produce up to 200 volts on reverse spike.


So you need a diode that can handle at least the 30-50 mA in forward current and up to nearly 200 volts on reverse breakdown.


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There is a guy over at the RT section of Luxury Touring Forum with the same question... maybe you guys could talk.


OBTW... given your board name, you should be really careful.


"Search" is an arcane function full of mysteries and rules/hurdles.


There is a sub-forum on it somewhere....


First ... always go to advanced search.

Next, if your search term has more than one word...enclose the string in quotes.

then, be careful of the date parameter... can be confusing.


For instance... I (Advance) searched under the Hexhead sub forum, using the term "switched power", and delimited the time parameter to Newer than 52 weeks and Older than one week.


Got a good result.


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The Fuzeblock comes with good diode protection on board. No other fuse panel (e.g Centech, Eastern Beaver, others) does AFAIK.


If you need a diode in the incoming line the easy and cheap way is 1A, 1500 Peak Inverse Volts (PIV) from the Shack. They're about 50 cents each. It has to go in in the correct direction in the line (50-50 chance if you guess) but no worries if you get it wrong and no power goes to the relay - just turn it around. Of course, a VOM or learning to read codes on stuff prevents the error in the first place.


Yes one can use a protected relay but I don't agree that most aftermarket types are protected (though OEM uses on many modern vehicle are using protected relays for the same reason you should have diode protection on the bike). The Hella types that are so commonly encountered in Centech installations are not, for example. As noted, one can tell by looking at the symbols on it, if it is marked and you understand the symbols. It is a fact that many available relays are not marked so one should assume they are unprotected unless known otherwise for certain. Its pretty easy to buy a protected relay that will work in whatever config you've got at any auto parts place but you may have to paw around a little in parts boxes in the back. $10-20 for most.


PIV spikes can be very high voltages and should not be ignored on machines with expensive computer modules. BMW publishes nothing that would tell us what, if any, useful protection features are built into the BMS, ZFE, etc..Perhaps they are superbly protected and additional protection is superfluous but we'll never know..

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Thanks fellas, Radio Shack it is. 1000-1500v 1A diode (PIV) (as I already have the relay) Across the trigger in wire to the relay.


IIRC my college physics teacher said power flows across the diode to the stripe, maybe my odds are 60/40 now, I do have a DVOM with a diode checker, guess I should figure that out too :)



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My screen tag came from a DR650SE i purchased from my brother in law after his garage burned to the ground with his three bikes in it. The DMV thought I should replace the license plate, but I liked the droplets of plastic dribbled on it, plus the smokey hue!


For the first year my garage would smell like a BBQ after I rode it.


All that is not to say I have n't seen a few sparks or let the smoke out of a couple elctronic devices in my day.

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