XS500 Battery Drain

M

Marklorenzo

New Member
I have a 78 XS500. I keep running into a battery drain problem which is frying my battery. Recently I have tested the leads coming out of this relay switch.





Not sure which relay this is. Not finding anything on wiring diagrams. One lead coming out of it reads about 12.3 volts with it unplugged, key off. When I plug the relay back in I hear a click and my volts drop to 11.1 instantly. The relay gets very hot also. Any ideas?
 
Re: '77 XS500 project - single Mikuni for both cylinders?

My battery was completely drained over night. Now my battery will not recharge up. Battery tender flashes red and normal charger fails to charge also. I don't want to keep replacing batteries. I left bike with relay unhooked for a week and had no draining.

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Look at the four prong connector the relay plugs into- are your wires :

Blue with Black stripe
Black
Yellow
Red with Yellow stripe

??
 
Yellow. red with yellow. Black. And blue with black. I decided to open the casing up. Found a corroded mess. I found a small lot of electrical relays from this bike on ebay but it could be corroded also. Is there a relay I can purchase at the auto parts store to mimic the same thing?

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That's a standard 12Vdc SPST/NO relay ( single pole, single throw, normally open relay )
When power is applied to the relay coil, it pulls closed a set of contacts to complete a circuit.

I sketched a diagram for you, across 1 &2 is the coil and 3&4 is the load side circuit in this example:



Also pictured above is a good used relay I have that's for sale. If you are not electro-savvy enough to find and wire in a suitable equivalent... or bypass the need for a relay completely, you might want to buy one that you can just plug in.
 
What it basically does is pass 12V+ voltage to your right bar controls, specifically for the for the "lights on/off" switch. It will only pass power on the contact side of the relay if the coil side receives voltage from the alternator via the yellow wire. ( when the engine is running )

The relay gets power directly through the Red / Yellow wire from the fuse box. As this wire is always hot, it will drain the battery if shorted to ground inside a corroded relay like yours/, even if the key is off.
 
I haven't been on here for along time.If you guys need electrical junk for these bikes holla at me.
 
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