blowing bulbs- revisited !

i *might* have double posted this - apologies if so...

hi all, please could anyone who is bored enough have a look at these 2 wiring diagrams for me... they are both for the same motorbike, but one is an old one and the other one is a later (factory modified) one... the older one is prone to blowing headlight and tail-light bulbs (even LED ones) but the newer one is much better...

used

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The old one blew bulbs 'cos of the crappy regulator. The makers knew this so they fitted a better regulator c/w bleed resistor. The improvement lies with the new regulator alone and not minor wiring changes. The answer lies with the new regulator internals.

thanks, but why might the regulator have 5 wires? i can't see what the extra wire is (or could be in another application) doing cheers, andy

in that case... what makes a crappy regulator a crappy regulator ? both regulators (old and new) charge at 14.8volts and never exceed this peak.... the output is 'smoothed' by a battery... so what could a regulator do to make the bulbs blow ? thanks! andy

it's simple.. it's what you call poor connections. Poorly designed branch circuits can cause problems where for example, instead of the bike making it's connection directly from the battery post to the ignition switch system and from there to the electrical. It may connect higher on the legs closer to where the alternator output regulator is connected. If the leg from that point going back to the battery for charging purposes has a loose connection. Higher voltages will appear because the regulator responds too fast in forcing more output between the phases. It's very possible that the regulator has a modular system where it is required to be plugged in to complete the circuit and if the connection becomes bad inside! for example a bad solder joint on the board, you can have problems like this.

ok i understand that, but if you look at the diagrams you'll see that this isn't the case... and the wiring is indeed virtually identical on both model releases of the bikes our prime suspect at the moment is that the earlier model has a far inferior battery fitted - my feeling is that it could well be possible to exclude the change of regulator as being the solution from the given information ? but i would be interested in any thoughts on this thanks, andy

Since this was answered the last time you posted it, I'll add my solution.

Install the new regulator. It *must* be broken in after installation. To do that, put the motorbike in reverse, and ride for a mile. This works best on April 1.

De

last time we didn't know that the regulator has been modified on the ones which don't blow bulbs - are you saying therefore this is irrelevant?

yeah thanks, :-)

My thoughts are that the new regulator works differently in that it does not rely on the battery internal resistance to control the charge current. So if the battery is getting old and its resistance is increasing, then you will get a higher voltage spike till the battery catches up in a sense. :) ?

sure - I've got lots of ramblings - had a bike where the batt ground wire broke at its frame ground. Driving 45mph down the road (of course at night) & the low-beam pops out - switch to high-beam & pop its gone.

Has anyone tried replacing the regulator on a "old" bike that has the problem? Did it fix it? Do all of the old bikes suffer the same problem? Has this problem always been there (people always had to replace the lights frequently?).

The permanent-magnet alternator, by design, will produce increased power output as its rpm is increased. The only way to tame this increase is to utilize the excess power somewhere. This "bleed resistor" is a simple way to "waste" the same amount of energy as the lighting system would consume. Thus either the lighting system is "on" or the "bleed resistor" is "on" & the combination of both options provides a constant load to the permanent-magnet alternator.

The lighting circuit will consume about 2/3 the total (12V) power of the bike.

It appears that the "new" regulator has two outputs that get connected together when the ign. sw. is "on". One of the outputs has a direct connection to the battery for better charging of the battery at low rpm. The other output runs directly to its main load, the lighting circuit.

The lighting output does get tied to the battery charging output but the run is long & the wiring resistance will be quite high compared to the "direct connections" limiting the effects of being tied together.

First is to identify the problem...

It is difficult to design a charging ckt. using a permanent-magnet alternator that works equally well for slow speeds/short trips as well as high speed/long trip conditions (& do it as cheap as possible).

To keep it simple the OEM used a PM alternator (cheap). This alternator has to be powerful enough to run full lighting, around town, at low rpm & still recharge the battery on every trip.

Once the battery is recharged, the regulator must get rid of the excess power by wasting it as heat, as there is no way to reduce the power output of the PM Alternator. Usually short-trip/in-town-driving barely keeps the battery charged so little heat needs to be wasted.

But on longer/high-speed (rpm) trips the battery quickly recharges & LOTS more power must be wasted to keep the voltage down (both regulators charge the battery at peak ~14.8volts on a long run using

On a old bike with the problem try a new battery & _really_ inspect _all_ the connections. All clean? Tight? Fuse holder & fuse very clean & the fuse clamps very secure? Ground wire attached to the frame & the wiring harness OK? No frayed wires at its connector? Bullet connectors are very clean & tight?

If after doing the above the bike still has the same problems then perhaps the OEM design is faulty. After all they did redesign it in later models.

A couple of things you could try... Get an electronics friend involved if you want to try any mods. Or be certain you know what you are doing :)

If the old voltage regulators are just regulating at a higher than normal voltage, then perhaps adding a single diode in series will help. It will drop the voltage ~0.7V.

Depending where it is installed, either... the whole system voltage will become ~14.1V, including the battery float voltage: (install in series with the regulator Pos. output Red lead)

or just the lighting load voltage will become ~14.1V (install in series with the Red lead going to the Ign. sw.).

The new schematic shows a 15A fuse in the batt lead so a 25-30A stud-mount diode should be ok. Mounted on a heatsink & very well insulated/protected from ground.

The other idea would be to use a "new" model voltage regulator in a "old" bike by connecting the two output leads together at the regulator & treating it as a 4-lead regulator.

I would really try to find out how the new regulator was designed first. It does have two outputs but its possible that they are regulated somewhat differently.

BUT, after all that, why do both old & new designs show the same battery charging voltage of 14.8V? I dunno. It kinda suggests that the "old" bikes have other problems causing lamp burnout. Perhaps it is the length of time the battery voltage is held at 14.8V?

Keep us posted & good luck! kc

To reply add xyzzy to subject line.

hi kim, many thanks, that has some really helpful ideas in there - i will email you shortly if you don't mind! andy

Sure :) E-mail addr is valid.

Ignore the "To reply add xyzzy to subject line." It was left over from previous testing.

Some notes I found out about this fifth wire...

Initially I suggested the regulator might have two outputs but more likely is that the fifth wire is an external sense lead the voltage regulator.

The 4-wire regulator would have its sense lead tied (internally) to the Pos Batt output wire.

The fifth-wire sense lead should terminate where the voltage needs to be regulated - the battery - to keep the battery properly charged.

The wiring diagram for the bike will show the actual routing of this wire. The schematic just shows what is connected to what, not the actual wiring layout.

kc