Datel readings

[ionbeam]

Just a quick hit and run post here.

I've found that a number of older Gen I bikes have a lot of voltage drop between the voltage rectifier and the battery. There is no one single cause, it is an accumulation of little voltage drops that total up to a significant loss by the time it arrives at the battery. The large voltage drop caused by your PIAAs is one indication that you are losing volts someplace in your electrical system. By 4k rpm to 5k rpm the Electrosport should be able to run the PIAAs with no problem.

As everyone is saying, you want to measure voltage right at the battery terminals, it is the voltage at the battery that counts. When my motorcycle was young I always had 14.3 - 14.4 volts at the battery with a minimum electrical load, and 13.4 volts when my PIAAs were running. These days I show 13.9 volts at the battery and ~12.4 volts with the PIAAs on. This is un-good, so the PIAAs have been off for a while. If I measure the voltage directly across the output terminals of the voltage regulator I do actually have 14.4 volts, but by the time it arrives at the battery I have 13.9 volts. I lose a tiny bit of voltage at the voltage regulator connector, I lose a bit more at the fuse block, I lose a surprising amount across the main fuse. You do not want to run your electrical system below 13 volts.

FWIW, your Escort is closer to 10 watts and the GPS around 18 watts.

Also, the voltage regulator works by taking the excess power being generated by the stator and dumping it to ground. Even though the electrical system may be lightly loaded, the stator is still working hard because the voltage regulator is dumping a lot power to ground, generating heat as a byproduct. If you doubt this, after the motorcycle has been running for a while put your hand on the metal body of the voltage regulator. Don't worry, the burn blisters will heal in a couple of weeks. On second thought, the voltage regulator may be a good source from which to make a coffee brewer.

I'll see how this thread degenerates and be back later...

 

[charismaticmegafauna]

Just a quick hit and run post here....., the voltage regulator works by taking the excess power being generated by the stator and dumping it to ground. Even though the electrical system may be lightly loaded, the stator is still working hard because the voltage regulator is dumping a lot power to ground, generating heat as a byproduct.

I'll see how this thread degenerates and be back later...

Isn't that just about the DUMBEST way to design a charging system....? :angry:

But:

If you run alot of electrical accessories at low engine rpm -- the voltage drops and the current in the stator increases (because, the load is there) and the stator , subsequently, fries.

 

[Warchild]

Isn't that just about the DUMBEST way to design a charging system....? :angry:

One of the main reasons that oil-cooled (oil-heated?) alternator systems are used on so many bikes is simply that it makes good sense from a space-efficiency standpoint. Air-cooled alternators can be significantly larger.

Now, if you have the space for it - like in-between the 'V' of a V-4 motor ala the ST1300, or in the cavernous engine bay of a gold-wing, etc, etc, then you can afford the luxury of a million-jigawatt air-cooled electrical system.

Too, most manufactures still to this day don't appreciate how much electrical goodies we tend to put on our bikes, even purpose-built two-up touring bikes like the FJR. You Gen II guys are fortunate you have the 590-watt stator from the factory. The pathfinding Gen I folks who are LD Riders have had to go the Electrosport route, which can be problematic if the install isn't done absolutely right, and even then, some folks still develop problems. And there has been a few instances were we've still seen some Electrosports fry up even when installed correctly and not overly abused. I had problems with my first one (but it was my own doing - failed to retain the stock R/R connector, which is NOT a good idea). My second Electrosport has been kicking *** for 40,000 miles now, and believe me, here in the dark, cold PacNorWest, my electrical system gets pushed to the limit frequently.

But then, I husband it closely with the Datal, and never really run below 13.3v on a continuous basis. This is key to a lengthy stator lifespan for oil-heated... er, oil-cooled alternators.

 

[FJR919]

I installed my Datel on my '08 using a reed relay from Radio Shack. Reed relays have minimal current consumption and are very limited in what they can safely switch, but for the Datel it's fine. This allows me to have an ignition switched direct reading of my battery voltage. My numbers run 13.8 to 14.2 most of the time.

 

[Ignacio]

Also, the voltage regulator works by taking the excess power being generated by the stator and dumping it to ground. Even though the electrical system may be lightly loaded, the stator is still working hard because the voltage regulator is dumping a lot power to ground, generating heat as a byproduct.

You're right! I had that wrong and had forgotten.

It then doesn't really matter for the longevity of an alternator whether you load it down or not? It runs at 100% all the time.

 

[SkooterG]

FWIW, your Escort is closer to 10 watts and the GPS around 18 watts.

Wow, I had no idea. I thought both those items would only be a couple of watts each.

 

[mcatrophy]

...It then doesn't really matter for the longevity of an alternator whether you load it down or not? It runs at 100% all the time.

My old Tiger Cub had a 3 position light switch that also controlled the three alternator windings.

With headlights on, all windings were used to drive the electrical system.

With just parking lights on, two windings were used to for the charging, one was short-circuited.

When no lights were on, two were short circuited.

The energy loss in the shorted coils is only due to their winding resistance, their inductance limits the current. If there was no resistance, there would be no power loss, even at their maximum current.

Interestingly (if you are a little geekish :boredom: ), this short-circuit current is near enough constant, regardless of engine speed, since although the open-circuit voltage generated rises with the engine speed, the reactance of the coil's inductance also goes up with alternator frequency. Don't confuse this with when charging a battery, where the open circuit voltage has to be above the battery voltage in order to give any charge.

This load dumping method prevents very high voltages being generated in unloaded coils.

The down-side on the Cub was, if your headlight bulb failed, the battery would start boiling :evil2: .

 

[charismaticmegafauna]

It then doesn't really matter for the longevity of an alternator whether you load it down or not? It runs at 100% all the time.

My point (above) is: if you load the alternator to max (whatever wattage one you have) and then run the engine at less revs than than required for max-output (4K+, 5k) -- then you are effectively trying to get those stator coils to give you more than 100%.

High electrical load + low engine rpm = fried stator.

 

[Zorlac]

It then doesn't really matter for the longevity of an alternator whether you load it down or not? It runs at 100% all the time.

My point (above) is: if you load the alternator to max (whatever wattage one you have) and then run the engine at less revs than than required for max-output (4K+, 5k) -- then you are effectively trying to get those stator coils to give you more than 100%.

High electrical load + low engine rpm = fried stator.

No, it's a shunt regulator that just keeps the voltage below a set threshold, as you load the system, the AC voltage out of the windings drops and so does the rectified DC, so less current is shunted by the regulator.A permanent magnet alt is pretty old school, even my old Concours has a real alternator that has an DC excited field coil with an extra 200W to spare.

 

[charismaticmegafauna]

No it's a shunt regulator that just keeps the voltage below a set threshold, as you load the system, the AC voltage out of the windings drops and so does the rectified DC, so less current is shunted by the regulator.

What if there is no 'excess'? If the alternator is 'over-loaded'? (max-load -- running at half-rpm)

Lower voltage requires more current to satisfy the load....? No....?

 

[Zorlac]

Lower RPM results in less voltage out of the windings, therefore less voltage to the load and lower total current.

The alt is a simple AC generator, the only adjustment is RPM, if the load is fixed less current flows as the RPM's decrease.

 

[Duster19]

Well, my goal is to test the volts straight from the battery tonight and I'll be back to post what the "real" readings are. I simply want to get past my electrical issues. Heck, it ran perfect before I started to Farkle the **** out of it.

Dave

 

[mcatrophy]

It then doesn't really matter for the longevity of an alternator whether you load it down or not? It runs at 100% all the time.

My point (above) is: if you load the alternator to max (whatever wattage one you have) and then run the engine at less revs than than required for max-output (4K+, 5k) -- then you are effectively trying to get those stator coils to give you more than 100%.

High electrical load + low engine rpm = fried stator.

If you are trying to say the load will drag more out of the alternator than it is willing to give, it doesn't work that way, the alternator can only give what that particular engine speed can make it generate.

Put a 60 watt bulb on a 12 volt battery, it will "suck" its (60/12 =) 5 amps. Put it on a 6 volt battery, it won't take 60 watts worth of current (10 amps), but considerably less than the original 5, and so glow a dull orange 'cos it isn't 60 watts.

If the alternator voltage is insufficient (low engine speed), it simply won't provide the current your load is asking from the battery.

What you've got, in (believe it or not) simplified form, is:

Alternator_current = (Alternator_voltage - Battery_voltage)/Alternator_impedance

The load current doesn't enter the equation except indirectly as it reduces the battery voltage, a relatively minor effect.

Also, as I suggested in my previous post, the alternator self-limits on its current generation (and hence self-heating).

 

[charismaticmegafauna]

Okay -- I get it.

@ half revolutions it becomes (merely) a 250~300 watt alternator.

Apparently then -- all stator failures are caused by engine /oil heat (since, there can't be any excessive current in the stator)?

 

[SkooterG]

Apparently then -- all stator failures are caused by engine /oil heat (since, there can't be any excessive current in the stator)?

Good point.

So I have a question cause I am an electrical dunderhead..............

Is the current being produced, or 'going through' the stator dependent on load? I thought from above it is always producing the max current it can and shunting any excess to the rectifier? In which case load would have no bearing on the stator current and neither on any adverse heat effects? Or is the stator just producing max voltage all the time? (I don't think that makes any sense, but ?!?!?!)

I am so confused!!!

 

[user 213]

My old Tiger Cub had a 3 position light switch that also controlled the three alternator windings.

That's what that was for! I always thought it was an On/Off/Flicker switch.



@Duster - What are you using to control your heated gear? Sounds like you need a Heat-Troller to ease some of the load on your system and give you more adjustability in case you need lights and heat.

Linky

 

[charismaticmegafauna]

So I have a question cause I am an electrical dunderhead..............Is the current being produced, or 'going through' the stator dependent on load? I thought from above it is always producing the max current it can and shunting any excess to the rectifier? In which case load would have no bearing on the stator current and neither on any adverse heat effects? Or is the stator just producing max voltage all the time? (I don't think that makes any sense, but ?!?!?!)

I am so confused!!!

I'll give it a try....(but, you can see from above, I'm no expert).

At full-output revs (4K+~5K rpm) a Gen I puts out something like 490 watts of electrical power and a Gen II, something like 590 watts of power. If you exceed that load (no matter what rpm) or if you use more than the alternator can put-out (say use more than 250~300 watts at 2,500 rpm) -- then the power users (bike, lights, etc.) start taking from the battery.

I don't think you need to worry about volts (pressure) or amps (current flow) through the stator or at the rectifiier/regulator?

The charging system puts out all it can -- all the time (but at lower revs it just puts out less). "All it can" is power measured in Watts. V x A = W

A voltmeter is just a way to show when (in the FJR's case) the 'load' (bike, lights, etc.) is taking from the battery.

 

[Zorlac]

If the bike is at say 4500-5000 RPM's and you keep switching on stuff as the Datel meter starts reading below 13.1V you are then loading the stator to more than it's rated current, not to mention that the engine oil is probably at 180-200F so that is the ambient temp for the stator windings, now the added current raises the wire temp say an additional 50 degrees above the oil, so you're looking at sustained 250F.

The enamel insulation on the stator winding wire starts to degrade and adjacent turns start to gradually short to each other and the stator goes **** up.

 

[C&C]

I'll give it a try....(but, you can see from above, I'm no expert).At full-output revs (4K+~5K rpm) a Gen I puts out something like 490 watts of electrical power and a Gen II, something like 590 watts of power. If you exceed that load (no matter what rpm) or if you use more than the alternator can put-out (say use more than 250~300 watts at 2,500 rpm) -- then the power users (bike, lights, etc.) start taking from the battery.

I don't think you need to worry about volts (pressure) or amps (current flow) through the stator or at the rectifiier/regulator?

The charging system puts out all it can -- all the time (but at lower revs it just puts out less). "All it can" is power measured in Watts. V x A = W

A voltmeter is just a way to show when (in the FJR's case) the 'load' (bike, lights, etc.) is taking from the battery.

This is the best explanation that I've read so far (at least to my understanding of the system).

One more point, it is also my understanding that the theoretical voltage for a wet-cell type battery is 2.2 volts/cell (optimal). This then translates to 13.2 volts optimal. So, if your voltmeter is higher than this threshold level, you battery would be in a charge state, below that, the battery would be in discharge state. By checking your voltage over a period of time, say minutes, (if you are in discharge mode) the absolute number would slowly or more rapidly decline depending on load. It's probably more important to be monitoring the direction of the voltage value (either up or down) rather than an absolute number.

 

[Capt. Bob]

It's probably more important to be monitoring the direction of the voltage value (either up or down) rather than an absolute number.

That is the true function of the volt meter.

There was a thread sometime back that Alan (Ionbeam) posted showing the different range of voltages and how they related to the charging system's health. By monitoring those changes in voltages (as you stated above) you got a pretty good picture of the success or failure of the system both of the battery and the stator.

Also, if you are like me and wired your meter to your fuse panel, don't despair. As another member stated, you could measure the voltage at the battery with a meter and compare it to the reading on the Datel meter. You can see the difference (it ain't much) and take it from there.

Edit: This is a great link. It not only describes the voltage ranges I spoke about above but also strikes a nerve on the so called "search Nazis", dog pile Fridays and if you read the whole thread,it may contain a cure for the common cold. If this ain't your cup of tea, then skip through to post#21 (I think).

Clicky