My last electrical question was too easy - bike electric tricky one!

[Gingernutz]

Hi all, happy christmas! After years of bodging accessories onto various live wires with gaffer tape and prayers, disconnecting them was interesting. I have a heated vest, grips, autocom, satnav, trickle charger and occasional phone charger. I have decided to add a home made accessory fuse box to the new bike. It will be in its own box and comprise of two busbars- one negative and one positive, and a relay connected to a positive when ignition on wire. The kit will be powered by the battery so there will be no additional load on the loom. I've copied this set up from elsewhere.



This looks ideal but......... I'd like to have some terminals on whether the bike is on or not. (Trickle Charger phone charger). I understand a relay with a fifth pin may be the way forward. What do you geniuses reckon? If I leave the negative bar solid but split the positive leaving these two on their own, is it just a matter of connecting 87a to this end? Or will these are on when  the bike is off - which is probably okay too.

This is the best resource page I could find.
http://www.12voltplanet.co.uk/relay-guide.html

[richfzs]

If you use a 5th pin (87a), then it won't be live when the bike is running - surely not what you want?

Just take a loop from pin 87 to your permanently live distribution bar. Be interested to see what you use for those distribution bars, I've had a similar challenge on the charity Bikes, found a solution but it wasn't neat and pretty!

[Gingernutz]

Hey Rich, I didn't explain well - I need a mix of live when on and off. If the 87a only works when off then it would be 'okay' because the main one on that branch is a trickle charger. I rarely use the phone charger but it is handy to be able to mm leave it for an hour after the bike is parked up. I'll post a picture when finished - hoping for a neat job than I can move to a new bike in a year or two with little hassle

[richfzs]

Aye Paul, I got the bit about needing some on and off, but thought you'd want the "on" to be on whether the bike was off or on, and the "off" to be on when the bike was on and off when the bike was off. If you see what I mean :rollin

So what you're suggesting is ok for the trickle charger, but no good for the phone charger (assuming you want that to work while you're riding bike AND when it's parked up). 

Will try and redraw your sketch in a bit, so it'll do both.

[Gingernutz]

Yup that about sums it up ta.

[richfzs]

Something like this.


You essentially need a different distribution bus, for your trickle charger & phone charger. As the phone charger will always draw a wee bit of juice even when doing nowt, I have a little inline switch in my setup as well.


The 2nd negative bus I've shown, can of course be the same one as your original, just easier to draw it seperately.

[Gingernutz]

Thanks Rich, I was hoping to have it self contained with only one set of wires coming from the battery. I understand your point that the negative can be the same one but I need to try to get my head around who it would look. I'll redraw it as one.

Thinking again - I wonder if I connect the positive side of the charger to both the positive busbar and 87a. In that case it will charge in on and off.

For the trickle charger I will connect just to 87a and negative bus.

Does that sound correct?

[Hamos]

You can still have it self contained, you just need to separate your +ve bus bars in the box so you have one that runs off the battery direct and is always on and the other is fed from the switched feed relay.  The negative bus bar can be a common negative for all.

You would have 2 +ve feeds from the battery, 1 directly to the "always on" bus bar and the other to the relay and then onto the "switched" bus bar.  You can wire 2 wires to the 1 connector at the battery terminal and split them off later to keep it neat.  Or just wire from battery to pin 87, then take a wire from pin 87 on relay to the "always on" bus bar and then wire the rest as per diagram.

You can buy a FuzeBlock that does this job for you,  but it costs £70, however it is one self contained unit.

I can do a wiring diagram for you if needed.

[richfzs]

What hamos has said there, is no different, electrically, to that which I drew (except when he mentions 2 wires coming from the battery, that means 2 fuses, which is obviously undesirable). You can put the 2 distribution buses in one box, no problem, and connect the permanent bus to the line from the fuse, and 87, on which ever way is convenient. It'll all be the same, electrically.

No need for another diagram - anything else would be a implementation design, which we can't do until you've got the kit to hand.

[Gingernutz]

Thanks again guys


This is what I have come up with having played with using a second relay and a second busbar and not being happy with either I have gone back to the less than ideal not charging when the bike is running for the phone charger. Its not ideal but I so rarely use it its not a problem and I can work around it





The main thing is I have only one set of wires from the battery and self contained unit to swap out later which has the option to trickle charge the battery


I think this should work- unless I am missing something!


I have isolated the last two positive terminals from the rest of the block and these are live when off.


Anyway playing about beats the shit out of watching downton abbey  :z

[richfzs]

If you take your green wire, and connect to 87 instead of 87a, you have the same thing, electrically, as in my sketch (except for the switch inline to the phone charger) . And you have the phone charger available at all times.

[Gingernutz]

Doh! - of course  :o  thanks mate

[richfzs]

Happy Christmas :-)

[clayt74]

I would include a fuse to each device feed rather than just one large fuse protecting it all?

[richfzs]

Yeah, that'd be a sensible addition. Makes for a whole load extra kit in (or outside of) the box though.
That said, looking at what the items being connected are, they've mostly probably got an online fuse in the wiring provided with them anyway. Perhaps only the phone charger that doesn't, so only 1 that  ends adding?

[Gingernutz]

I understand the fuse each preference but as Rich says my kit all comes with them fitted inline so my diagram is a little simplistic.

I wonder if it matters anyway - the advice is normally to fuse as close to the battery as you can. I wonder could a wire get hot at the other end of a fused circuit? Off to Google again!

[Gingernutz]

This explains it well - and explains why you might have several fuses

When connecting a device to your bike you want to make sure that the fuse is located as close to the power source as possible. This is because you are decreasing the odds that a short will happen between the power source and the fuse. If your wiring shorts to ground (the frame, etc.) between the power source and the fuse, then the fuse won't do any good. By only having a small amount of wire between the connection on the power source and the fuse you decrease the odds that it will short out along that length of wire.
A short is more likely to occur after the fuse -- where most of the wires, and devices, are located

So if you have one right at the battery why have another??

[richfzs]

Yep, you want one as close to the battery as possible. That one (and the wiring to / from it) has to handle the current drawn by all the accessories that could possibly be in use at the same time.

The wiring supplied with your individual accessories, will only handle what that accessory needs. So if that accessory needs 0.5A max, that's all the wiring will cope with (plus a bit for contingency). Now suppose that accessory fails, and shorts through somehow - if it doesn't have its own appropriate fuse, the only thing protecting your bike is the fuse you've put in as close to the battery as you can. Which is likely going to be 20A rated - and the little wires supplying your accessory will potentially go up in smoke. so you need that accessory protected by a 1A fuse, which will blow much sooner than the 20A, and protect your bike.

[Fazafou]

I do something similar to all new bikes now (not with the ignition off live though), but don't understand why you're bothering with a negative block. Surely the point in making the frame negative is for this reason, so you can tap into it wherever you are on the bike, rather than trailing a second line of wires round for each accessory.

No big deal, but just didn't bother myself and makes feeding live only wires around the bike much simpler.

[richfzs]

Yeah, you can do that, same thing, electrically, and can be less hassle, as you say. As long as you can find good frame contacts where you need them, isn't always the case. I tend to use a mixture, depending on the scenario