Jump Starter used as replacement for Battery

[dwalby]

Thinking it must be the starter relay so, I think I've located it near the battery, it's got 2 30amp fuses either side, I checked both of these fuses and they are fine, I'm a bit stumped now what to do, have to ring a Yamaha dealers tomorrow maybe.

Assuming you have a voltmeter, so don't give up yet.

I'm going to give you a step-by-step from the relay to the starter motor, but after that I'm going to give you a quicker way depending on which terminals you are able to find easily. So read through the description, then read the last paragraph.

If you are sure you have located the relay, there should be two terminals with large wires connected to them, that's where the relay bar connects one terminal to the other when you hear it click.

1. measure the voltage drop across those terminals when the relay clicks, it should be very close to zero. If its several volts, then the relay needs to be replaced.
2. if that voltage is close to zero, next measure the voltage from either terminal to ground (engine block, frame, neg battery terminal) when the relay clicks, that should be reasonably close to 12v.
3. If that voltage is low, figure out which terminal goes to the battery positive and which goes to the starter motor. If you can't trace it then disconnect the battery positive terminal and do a resistance measurement from the battery + terminal wire to each of the relay terminal wires. One should be near zero resistance, that's the one that goes from the battery to the relay.
4. reconnect the battery terminal wire and this time measure the voltage drop across the battery-to-relay wire when the starter is pressed. If you get more than a volt or so drop then you have excess resistance in that wire that is causing the voltage drop. Look for corrosion, bad terminal connection, etc.
5. If no fault found yet, the other wire from the relay goes to the starter motor. Try to find the terminal on the starter motor that its attached to. Do the same voltage measurement on that wire as in step 4.
6. if there's no excess drop in that wire, then you either have a bad starter motor, or the starter motor ground path is bad.

OK, now for the quickest way. If you have access to the starter motor wires measure the voltage across the starter motor terminals while pressing the starter button. If you don't have 12v there, then move one of your leads to the negative battery terminal, and measure the voltage from each of the motor terminals to ground while pressing the starter button. If the motor ground is good you should see little or no voltage between that terminal and the neg battery terminal. Then start at the other motor terminal and work your way back to the battery + terminal from the starter motor with each step above, and see what voltage you have at each intermediate point (with the starter button pressed for all measurements). You should eventually find a voltage close to 12v with the starter engaged, which indicates the circuit is good up to that point, and the problem is downstream from there. If you measured each of the places specified in steps 1-6 in reverse order, then you should know which leg of the path is causing the problem when you finally get a good ~12v reading.

 

[mlheck]

A lot of these jump starters have to see at least some voltage to make sure you have the correct polarity before they will discharge, No battery No voltage. The down side to this is that if the battery has shorted out internally, then you are screwed no matter what.

 

[Larry Fine]

Thinking it must be the starter relay so, I think I've located it near the battery, it's got 2 30amp fuses either side, I checked both of these fuses and they are fine, I'm a bit stumped now what to do, have to ring a Yamaha dealers tomorrow maybe.

If you jump the two large terminals with a metal tool (it will spark) and the starter motor spins, it's definitely the relay.

 

[broc11]

Thanks a million Larry, I just done what you suggested and the bike started straight away, I am so delighted!! my knowledge of electrics is very limited, I was wrecking my brains all evening, I'll get a new starter relay ordered tomorrow, my thanks to you Larry and this brilliant forum.

 

[broc11]

Thanks dwalby for taking the time to write that very informative post, no doubt it will be of great help to others in the future, I done my best to follow your suggestions but when it comes to electrics I'm not great,I wasn't getting anywhere fast, I can figure out a flat battery /blown fuse etc and basic stuff ok but when it gets more complicated stuff I'm lost, being colour blind doesn't help either with wiring, Larrys post sorted me out in 5 mins, thanks to this great forum, I remember now doing the same thing on a tractor years ago at the solenoid near the starter.
when I got back into biking doing an oil and filter change was all I had the confidence to do, now thanks to this forum I can do brake/clutch bleeds, fit new brake pads/clean the calipers etc, thanks again folks.

 

[fnmag]

Glad you found that it was the starter relay.
Easy solution.

 

[dwalby]

yeah, glad you got it sorted. Since you're hearing a clicking noise at the relay, that would suggest the starter button is probably working OK and trying to energize the relay, but something isn't working properly inside the relay to close the switch. If you weren't hearing the relay click then jumpering across the relay wouldn't necessarily prove the relay was bad, if it wasn't getting energized properly.

Also, as these bikes get older the health of that entire electrical path starts to become questionable if the wires get corroded. So its not a bad idea to trace the path to see what it looks like, but I just realized you aren't servicing an ST, its a newer Yamaha, so that advice isn't really applicable in this situation.

 

[RaYzerman]

I would leave the battery in place also, it's rare to have one short. I'm not so sure a jump pack can take being charged at typical stator outputs of 14 volts, so once the bike starts, I'd disconnect it. A dead battery will usually have some capacity left in it to act as a buffer until you get to a repair place or home.
As far as battery charge state, 12.5 volts is 50% discharged and if you let it go that far too many times, sulphation will start and eventually the battery will deteriorate beyond help. Best keep it topped up. Yuasa chart attached.

 

[klaproth]

Are all the connections clean and shiny? Have you tried powering up the starter OUT of the bike? Sounds like you've isolated the problem to the starter or relay. I don't know what an FZ07 looks like, or how it's starter is mounted, but one idea might be to run a temporary connection down to the positive side of the starter from the battery to see if that'll make it crank. From personal experience, I can say that corrosion and poor connections are the problem 85% of the time.

Good luck on it.

 

[broc11]

Thanks,this bike is still like brand new,always garaged and has hardly seen rain,it looks like it's just the starter relay that has packed in for whatever reason, new one ordered should have it in a few days, hopefully that will be it sorted.

 

[ST Gui]

the starter relay that has packed in for whatever reason,

You might dissect it and see if you can spot the trouble — pitted or broken high current contacts etc.

 

[broc11]

I'll have a look, doubt I will be able to figure out what went wrong though. the part hasn't arrived yet, hoping it cures the problem.

 

[broc11]

Replacement part fitted and the bike started no problem, thanks again Larry for the tip.