audiomick

Quite rightly. Regardless of how much current is going through the contact, if it starts bouncing there wil be "constant" arcing across the contact. That is, over time, the end for the relay.

Yes, I know. I can see people's eyes glazing over as they read from here. Nevertheless, a quick word about coil resistance and power. I spoke once again to my electronic technician colleague. He confirmed that a solid state circuit providing the voltage to activate the coil of a relay would indeed be set up for a specific resistance, but the tolerance is likely to be very high. As long as the replacement has a resistance "in the same order of magnitude" it should be fine. He also confirmed the importance of a strong contact, particularly in a high vibration environment like in a motorcycle. Therefore docc's preference for a "stronger" coil is justified.

Regarding that: the spec. sheets refer to 10 ~ 40 Hz. . I thought that was probably to low to be relevant, but it turns out I was wrong. 2.4000 rpm is equivalent to 40 Hz, i.e. 2400(rpm )/ 60(seconds per minutes)=40 (Herz=cycles per second). So the stated frequency range is relevant to the lower part of the real world rev. range of the motor. Apart from that, other pennies have been dropping in the course of today. Regarding the coil resistance, which I hadn't done all that much till now: coil resistance is tied up with coil power, which docc has mentioned a couple of times. The corelation is in the formulae. Coil power can be calculated with the formula P = VI https://en.wikipedia.org/wiki/Electric_power and the current in the coil with I=V/R https://en.wikipedia.org/wiki/Electric_current The Picker spec. sheet quotes coil resistance at 120 Ohm for the 1.2 W version, as does the spec. sheet for the CIT relay. That gives us a current in the coil of 12V divided by 120 Ohm = 0.1 Ampere. So, negligible. Therefore I would assume that the coil power (apart from holding the relay open/closed under mechanically difficult conditions like excessive vibration) or coil resistance (looking at it from the other side) is pretty much irrevlevant. Mechanical switches such as the ignition switch, light switch, and so on, can certainly handle that sort of current. The exception might be the relay that is switched by the ECU. The switching voltage is generated by the ECU, a solid state circuit (i.e. probably a transistor). Such things are set up to expect a specific resistance at the othe end of the wire. If the resistance at the other end is too high, not enough current can flow (I=V/R, and V is constant). If the resistance is not high enough, too much current could flow, and the output stage of the ECU might shit itself. Therefore, I would not like to see the coil resistance /coil power for the specific relay that is switched by the ECU deviate to much from the specs of the original relay. Otherwise, I think that (coil resistance) is a spec. that doesn't have to interest us too much.

Splitting hairs: the manufacturer would most likely say that the spec. sheets support the claimed rating. We can only trust the spec. sheets, or not. Nevertheless, they both seem to be at the top of the range that I have seen for "high current" relays. "Bigger" ones, i.e. 40 A. or more, seem to jump to a 9.3 mm blade on the load connections (30 and 87/ 87a), so they wouldn't fit in the sockets. I like the Picker a little better, because the NC contact claims a higher rating (25A. vs 20A, both @ 14V). The "vibration resistance" spec has a higher number next to it (2.7mm double amplitude), but I don't know if that is relevant to our application.

That is probably the pertinent point. A "middle class" relay may well be "good enough" when the rest of the circuit is well maintained. When everything else is marginal, the problem is going to show up some where.

No. It's nit-picking, but it's also only about the definition of "nominal". In the accepted jargon, bikes and cars (nearly always) have a "12V electrical system". Look here: https://www.collinsdictionary.com/dictionary/english/nominal one talks about a "12V system" even though everyone knows the real voltage is not 12V. Therefore, per Definition, 12V is the nominal voltage. Nevertheless Yes. According to my limited knowledge of electrics, absolutely correct. and... Yes. An electrical part getting hotter than normal is an almost certain sign that a resistance is increasing or increased. By that I don't mean the component "resistor", but rather the resistance, for instance, across the contacts. i.e. if the relay starts getting hotter than it normally should be, it is a fair assumption that the contacts might be going bad = replace it. Edit: I suppose a bad contact in or to the socket could also make the relay heat up. That would be worth a look at before spending money on a new relay. another Edit: if a particular relay is always running a bit warmer than the others, then of course one could consider a higher rated relay in that position. One with a higher rating would most likely run cooler. The question is, is the relay in question running too hot? The temperatures you reported in that linked post, docc, don't look "too hot" to me. Highest reported temp. 147° F = just short of 64°C. That is still 20°C below the "max. temp." specs of typically 85°C that appear on various spec. sheets. So probably ok.

Thanks docc. So, terminal to the back of the bike, and positive on the left from the rider's perspective.

Daniel Graig. The old, familiar story, but in "modern". I read about that in another forum. Apparently the hazard warning goes off under very heavy braking, but can't be switched on manually. Curious...

Yes. Don't know where it goes yet, I'll have to have another look to find that out. I assumed it was standard something or other, as the pinkish sleeve on it is the same as the other thick cable that is connected to the + terminal. Might be a mod, though, I suppose. PS: can someone post a photo of a standard, or near standard, battery? I gather mine is not in the same orientation as a standard one. Knowing which way around it was mounted originally, and where the + and - terminals were, might help me understand what has been done to the wiring on mine.

I find it interesting that they quote "Maximum Switching Power 350 W" (power rather than current). Given that, they are a little inconsistent (I think) by not quoting a voltage for the maximum continuous current. Note that there are voltages given in the contact ratings. I consider it impossible that the maximum current could be the same at any voltage, but I might be wrong. That they specify maximum switching power allows the assumption that a voltage other than 12V could be switched by the relay. Further up I linked to this: https://en.wikipedia.org/wiki/Electric_power where we can see that p = VI, i.e. power is the product of Volts x current. We are talking about motorcycles with a nominal (there's that word again...) voltage in the wiring system of 12 V. That means that, according to the specification of 350W switching power, the relay can safely switch 29,17 A. at the nominal 12 V. As we all know, in a healthy electrical system on a motorcycle the voltage is more like 12.8 V or so, so the real world current that can be safely switched is slightly lower. That this figure is lower than the the continuous carrying current should be no surprise, as we had already established further up that it is generally the case that the "carry" current is higher than the "switching" current. If we consider other voltages and the specification of maximum switching power, then the relay can safely switch anything between 350 A @ 1V to 1A @ 350V. Theoretically, at least. Some more maths: Take the spec 1C : NO 30A@ 14V DC. 30x14= 420 Watt. go back to the nominal 12V in the electrical system: 420 / 12 = 35 which is the stated continous current. Once again, I think they are a bit inconsistent in those specs, i.e. jumping around with the voltages they are assuming, but I'm guessing. Anyway, on the basis of those specs I would assume a safe switching current on a motorcycle of around 30 A., and a safe continuous (carrying) current of 35 A as stated on the spec sheet. If the relay gets really hot, those figures will both be lower, but I as already mentioned, I don't think the relays are likely to get that hot on a V11.

I've seen quite a number of you tube videos that were claiming to be "sound checks" for some vehicle or other. The idea that one can get a realistic idea of what something sounds like from a video that was recorded by a gopro, or better still a mobile telephone, that was then posted on the internet to be listened to on computer speakers, or maybe even a mobile telephone, is simply absurd.

I had a very good look at all of that, and I'm certain that the cable from the + terminal is not connected to the bolt behind the battery. I'll have another look now that you have all made me uncertain, but... What I saw was the "monstercable" with the connector with the yellow insulation that is connected to the - terminal definitely goes to that bolt. On the photo, one can see the same type of terminal at the bolt. That is the other end of that wire. There is also a connector on there that seems to be part of the original loom. Also, there is a cable that goes to the - side of the accessory socket that is installed in the fairing. If a cable from the + terminal were also connected to that bolt, the battery must already be short circuited to death. It isn't, so I am assuming I followed the wires correctly.

a P.S. to the last post: I spoke to my electronic technician colleague again today. He confirmed those assumptions, and went on to say that for our application, pretty much only the stated switching current is directly relevant.

That calling a you tube video a "sound check" is completely absurd. The mufflers look pretty tidy, though.

Almost always, in my experience.

more thoughts, which may or may not be useful. The relevance of the "maximum temp." specs have been floating around in my head all day. This confims what I already knew, i.e. that the resistance of a metallic conducter increases with increasing temperature: https://www.toppr.com/ask/question/why-does-resistance-of-a-metallic-conductor-increase-with-increase-in-temperature/ The relevant temperature seems to me to be the temperature of the coil. Given that the coil presents a resistance to the volts applied to it, it is going to get warm when it is activated. A resistor (in this case the coil) always gets warm when current passes through it. Something that is warm or hot is at a higher energy level than something that is cold, so the heat in the relay from the coil will be trying to get to the cooler air around the relay. Energy always travels from the higher state to the lower state. Therefore the ambient temperature is relevant to the operation of the coil. We already had made the point that the coil needs more volts to activate the relay when it gets warmer. If we take it as given that the available electrical potential (volts) is a constant, then the various formulae show that the coil is going to exert a weaker pull when it gets warmer. Power = volts x current https://en.wikipedia.org/wiki/Electric_power Volt is constant, so power is reduced when current is reduced Current = volts divided by resistance https://en.wikipedia.org/wiki/Ohm's_law so the higher the resistance, the lower the current. i.e. the warmer the coil gets, the less "pull" it can generate to acivate the relay. Secondary to that, the load contact, i.e. the contact that the relay is making, is also a resistance. Contacts always are. If the relay is switching close to or over its rated current, this contact is also going to be getting warm, and that heat is most likely adding to the heat in the coil because they are all in a tiny little box together. When the coil gets too warm, and "weak" as a result, it seems to me to be likely that the contact that the relay is making is likely to start jittering, or even open slightly and stay that way. This would lead to arcing, as has been referred to earlier, with the result that the load contact would either weld closed or erode away into uselessness. At this point, the relay has failed. Having said all that, I seriously doubt that the ambient temperature around the relays in a V11 would even get close to the numbers I have been seeing in spec. sheets (typically 85°C and 125°C). I have an idea how I might be able to check on that, but I'll get back to that sometime when I have had a chance to try it out. Anyway, I tend towards the following conclusion: We have discussed the lower permissable switching current at higher temperature ( e.g. 20 A. @ 85°C when the nominal switching current is 35 A.). Obviously the highest possible switching current is desirable, but I don't think that the maximum temperature is likely to be reached in our application. Therefore, I don't think we need to get leery about those "maximum temp." specs. . If anyone can see a fault in the logic, please say so.

Yes, I considered keeping mine for just that purpose. I didn't, because we already have far too much stuff lying around. But I have photos.

I can see that applying to paper gaskets, but I can't imagine that it would work for one with a metal core.

Shoei X11. Hmm, I believe that was the helmet I was wearing when I crashed in 2017. Mine looked pretty similar to the picture in that report. A couple of millimetres of material ground off on the chin piece almost exactly on the same place as his, and massive scratching on the visor. As the man wrote, a full-face helmet is the only way to go.

Fantastic. It's good when it all works out.

docc, I just noticed that I didn't respond to this That has been discussed in "Best Relay", I think Fuses all look ok. Yes, the wiring has been changed. However, the bolt holding several cables together behind the battery is not an unshielded postive, but rather a "common ground", i.e. it connects a cable from battery minus with a connector out of the loom and an addition that supplies the negative contact to an accessory socket up behind the instruments. So it is not dangerous, even if I am not completely happy with the solution.

That would make a certain amount of sense, but here it would also mean you (the bike) would fail the bi-annual roadworthy inspection. There has to be a switch, or a side-stand that folds itself up when the bike is stood up.

Hold the presses. I think that is turned around. It should be "resistive load" and "resistance". Resistance is how much a component resists the flow of current through itself. As noted earlier, work done (power in Watt) is the product of Volts and resistance. Resistance seems generally to be quoted in the spec. sheets for the switching coil, and therefore isn't related to the current capacity on the load side of the relay. Resistive load is the load that is induced by a resistance. As far as I understand it, this is related to what is called "carry" and / or "continous" load in as much as it specifies what sort of load is being continously carried.