Alternative Alternator Options

[crazy steve]

I don't even know if I'm reading the frequency scale by the bottom red scale or not? There is a GREEN scale and it's marked in the legend HfE, so not sure if that's the AC Hz scale...but it only goes to 500, but is more sensitive in the 0-50 range, which would make sense for analyzing house currents of 50-60hz??

If that's the real Hz scale, my problem is what scale to set the rotary switch to....but I'm thinking the 30VAC was correct, and with the needle on the bottom scale ~21 position, that would be between the 30 and 40 hz green scale!?!?

You'd set AC voltage to whatever you're measuring, in this case, the 30v scale, so you got that right. The problem here is this meter isn't going to give you a real accurate read (and you still need to know what rpm the alternator is turning at that frequency). However much you miss by, that would throw off your tach calibration. In this case, a digital meter will be a much better choice. But this is a pretty nice analog meter...

[TopCatGr58]

Well, I played with it a little more using my analog Dwell/tach/vom and made a tap off of the Orange coil wire at the TCI as the trigger wire. My Dwell/tach showed on the 4 cyl. scale ~1600 rpm when my OEM tach read 3k rpm, so my calculations of doubling the 4 cyl scale to get the 2 cylinder reading was correct. So..I do have a fairly accurate way of measuring the OEM ALT's rpm since it's the same as the engine rpm, and I can measure that with the Dwell/tach off of the coil TCI tap.

As I found out before, that other aftermarket ALT's with tach outputs have their pulleys sized to provide between a 2 to 3:1 crank ratio. Seems that these ALTs also take a lead off of 1 of the 3 phases for the tach signal, the ALT guru also told me that he could do the same with the Mini-Alt that didn't have a tach output. So...I'm betting and hoping that OUR tach/Alt will be similar, but I know that this is like apples and oranges!

Are we having fun yet?
T.C.

[natemoen]

Well I am still listening, if that's considered fun

[3Phase]

I tried the digital multimeter and it's not sensitive enough to get a count when turning the alternator one revolution by hand. I might be able to use an analog meter that can measure AC millivolts/microvolts and a reliable helper to count the needle pulses while I turn the engine but I don't have either one at this time.

For the pulley: some auto manufacturers use pulleys that bolt to the harmonic balancer, not to the end of the crankshaft. There might be one that can be turned around 180 degrees and mounted to the rotor so the 'dish' in the pulley puts the belt groove over the rotor instead of sticking out like Mad Max's lawn edger. Either way it will make using highway pegs or just stretching your right leg during a ride a lot of fun even if you blouse your boots.

Another problem is going to be keeping the stock rotor on the end of the crankshaft. Nothing is actually supposed to touch the rotor during normal operation and it is balanced with that assumption. The bolt and taper fit with no Woodruff key is only meant to hold the rotor itself in place at ~8,500 RPM against a magnetic load to generate electricity, not a friction load driving a belt with harmonics. Red Locktite on the taper and retaining bolt might work but it might not.

[TopCatGr58]

Well,

I've done some more NET research, and read lots of articles on Automotive alternators, their construction, theory, operation, etc.! From what I've found, "they" state that most auto alts are 6 pole...6 pairs of claw poles, so even though there are 12 points, they are north and south pole pairs, so that makes 6 poles. OUR rotor is a 12 claw, 6 pole paired rotor, so that's where I'm getting the calculation of its frequency from. 6 poles x 1000 rpm = 6000 divided by 60 seconds = 100 pulses/hz a second at 1000 rpm.

The 6 pole design provides for modest power output needs of automobiles, however, that need is rising with all of the extra computer/electronics and such, hence the 150-200+ amp alts out there, and they very well may have more poles?? But I'm going to assume that the Mini-Alt also has just 6 poles, easier to wrap the wires/manufacture than a much higher pole design, and at only 50 amps, it doesn't need more poles.

The problem now looks like the signal frequency from one of the 3 phase/legs from any aftermarket 6 pole alt would be the same as OUR 6 pole 3 phase ALT, providing they were spinning at the same RPM. SO...now it looks like to have a usable tach signal, the crankshaft pulley will need to be the same size as the Mini-Alt's pulley...~3" diameter. This makes it easier to find a pulley, especially in the 3/8" core size design, but this will SLOW DOWN the effective spin rate of the mini-alt. I can't find it now, but I remember finding a spec sheet that showed it's SELF EXCITING rpm at 1700...however that is using the 1 wire hookup. This alt can be connected to a switched 12 supply for the field wires that will get it energized and charging at a much lower rpm. I also had found a chart showing the amp power output for it at specific rpms, and at the base 1700 rpm, it was like 25 or so amps, and so even at IDLE rpm of 1000-1100 it will still at least put out close to the MAX 20 amps that our unit does, and so during simple 3k+ cruising rpm, it will be cranking out plenty of power to run AUX headlights, heated grips, vest warmers, radio, etc.!

I think this is still very doable. I'll be ordering one from DBElectrical, they sell same price from their site and ebay, getting it for my B'day gift to me!

Scott, the pulley on the END of the ROTOR/Crankshaft works better for mounting this thing, allowing it to be sticking out to the right side so it won't be so close to the carbs/jugs, with it's midline mounts position and the possible use of some shims, it should be easy to align with the crank pulley. I also was NOT going to have it OPEN like the OCC engine/clutch/tranny transfer belts on those harleys! I was going to make a thin sheet metal/aluminum shroud to cover the pulleys to prevent abrasive damage to our legs! And the smaller pulley will be under less torque/tension when the alt powers up, especially at higher loads.

I'll still be taking the bike up to the local auto shop to see about them trying to measure the frequency, but I'm more convinced about what we'll find now!

T.C.

[TopCatGr58]

Was thinking about what other impacts this mod will cause, and I realised that there won't be a trigger signal to the headlight relay when the OEM alt is bypassed!

SO...my question is what would be easier and work? Could we take a split off of the internal phase tap that will be the Tach trigger, and run it to the headlight relay switch wire? Would need to find where to splice into the harness BEFORE the diode in that wire so that the headlight relay will work and stay latched??

Or will it just be easier to perform the RLU or headlight relay bypass? But this IIRC turns on the headlight before you start the bike..unless you wire in a switch/relay?

Well, I'm going to go ahead and order this Mini Alt tonight, so hopefully I'll get it by next weekend, and can start on the mounting bracket fabrication and such. Fun times ahead!
T.C.

[TopCatGr58]

Okay, I promise, last post today on this subject!

Found that spec sheet. IT was for a 45 amp race mini alt, essentially the same as ours, I think Denso makes a bunch of these and some of these companies put their names on them and resell them, sometimes at riduculously raised "Racing" equipment prices!!

The "turn on" rpm has been stated from ~500 to 750 rpm. However the output graph for the 45 amp unit shows it not providing actual power until about 1500 rpm, it's cranking 15 amps, and at just 2000 rpm, it's doubled to 30 amps, and reaches it's rated Amps of 45 at 3000 rpm, but goes even stronger and fully peaks at 6000 rpm and 55 amps. The Alt is rated to 20krpm.

So...it looks like with a 1:1 pulley ratio, we'll have plenty of charging power at just off idle, and IF it has built with the common 6 pole Rotor design, then it'll be a straight bolt on match for our tachometer!

As stated in previous post, just need to determine the headlight latching relay wire to hook up. I'm getting "juiced" just thinking about this mod.

T.C.

[natemoen]

Sounds promising! The proof is in the pudding though and I ain't seen no pudding yet

[cywelchjr]

If it gets the same signal we should be able to just grab the one wire like the stock does and run it through the diode, which just gives pulsating DC which on a pulse triggers the relay which then latches not caring if it EVER gets another pulse out of the alternator.

If we still wanted a 2:1 ratio, assuming everything else is the same, it would not be too hard to put together a simple frequency divider circuit to bring it back down, but your right that if it will work at 1:1 it's much more plug and play. Just remember that if we NEED the 2:1 to make it work, and that doubles things I'm really sure I can figure out a simple mod to make things work properly. I'm figuring AC in, and AC and 1/2 the freq out the other side at the same levels. I seem to recall that there may even be off the shelf options that are not too spendy. But lets see where we get, cause no mods other than the alt it's self would be best.

[3Phase]

Headlight Relay

What?! Shields and guards over the belt and pulleys instead of a Road Warrior bike!? Noooo!

T.C., there are two different headlight relays for two different charging system connections on the XS11 and they use two different pinouts. Okay, there are actually three if you you count the XJ but I haven't looked at the XJ headlight circuit so I can't honestly say how it works.

Anyway, even though the two different types of XS11 relays will physically connect to either style of harness, the relays will not work at all unless you move the pins in the harness connector. That is not a good idea because the relays are different internally.

1978 --> 1979 models tap the common junction point in the stator wye for the headlight relay with no diode -- Yellow wire.

Tap one of the phase legs for the tach - White wire.

1980 --> 1981 models tap one of the stator phase legs and use a wire with a diode for the headlight relay -- White wire.

Tap one of the phase legs for the tach - White wire.

It should work whichever way you tap the alternator for the year/model of XS11 you have but doing that will instantly void any warranty on the alternator from any manufacturer so you will need to be very sure of what you're doing.

[TopCatGr58]

Update!

Hey Scott,

I reviewed the wiring diagrams for the 78-79 as well as the 80-81's. On the 80-81's they take 2 taps from the same ALT tap, run 1 to the tach, the other they put the diode on and run it to the headlight relay.

SO...for simplicity, I think for the 78-79 just take the same Alt tap, Y it, put a diode on one and connect it to the yellow wire, then run the other to the wire in the ALT Plug Harness side for the tach.

I contacted Geezer/Tony and he's going to send me some connectors for the ALT/Stator plug as well as the field coil of the Reg/Rect. I plan on running a 12 volt switched line to the SENSOR connector on the mini alt, so it can get a more remote voltage sense than right off of the charging wire, and hopefully it will also provide the field coil with some juice to activate and start it charging BEFORE the rated 1700 rpm "Turn On" speed which I hope is the self excitation speed?? I've found turn on speeds of ~500-750rpm on other places for the same style ALT!

Okay, I got the Mini Alt in today, and just placed it on the bike where it will be, the clutch cable will need to be flexed just slightly, but as you can see from these photos, there's plenty of leg/foot room, and with a simple sheet metal/aluminum cover, it won't cause any contact concern.











The Pulley size is 2.75" diam, and from what I can see using some very strong readers, and a maglite, I can count 6 pole pairs on the rotor, so it looks to have the same layout as our OEM alt, and so keeping it at the same 1:1 crank to alt speed should provide us with a very close OEM tach readout. I've got my B-I-L going to the local GRAINGER distributor to pick up the 3/8" core 2.75" diam solid Pulley...only ~$7.00 .
I picked up some 8Gauge wire at the auto store...$7.00 for ~3 feet, I already have the round eye crimp connectors for it to make it the charging cable.
8Ga is rated for 39 amps, should be sufficient, I don't think I'll be putting 40 amps worth of strain/load on the system. Also the larger 4 ga battery cables/connectors just had too large eyelet holes! Guess I could make 2 8 ga cables and connect them both for more capacity!

I missed the guy at the local shop by 10 minutes today trying to get a pulse count/reading on my bike! Will try tomorrow.

BTW, Seems that Geezer can get these things, and he said he could probably beat the price I paid! However, he showed me a CHROMED one in an email, they were running almost $50 more than the standard ones on the places I found them!?

PS, in the next to last photo, I've taken the reg/rect cover off, can someone confirm that any one of those screws I circled in red would be the place to put a TAP wire for the Tach/headlight relay?

PS, can anyone also tell me which one of the 2 flat connectors would be the Sensor wire vs. the idiot/Amp/Charging light connector?
Thanks.
T.C.

[DiverRay]

You will need to hook up BOTH of the connectors, TC. The one marked "S" goes to the battery, the "L" goes to the idiot light, and through a 5A. fuse via ignition switch.
That should keep you running. I THINK the tab that is 90 degree to the case is "S", but I'm NOT positive. I'm thinking it's wired like the GM alt., as that seems to be the "standard" for the Hot Rod crowd.

[3Phase]

T.C., what you're looking at with the alternator cover removed is the voltage regulator (the big thing with the fins on it) and the voltage rectifier diode plate with the output isolation diode. If there is a dedicated tachometer connector/tab I don't see it in your pictures.

You cannot see or get to any of the stator phase legs or the stator wye unless you remove at least the diode plate, maybe more. It depends on how the alternator is wired and it also assumes it is a Wye wound alternator, not Delta wound.

On the1980/81 XS11, like your Godzilla, the White wires to the tach and the headlight are from separate phase legs and they're not joined. I suppose it is to keep the loads balanced so one leg feeds the tach, one feeds the headlight relay and the third is not tapped.


The 1980/81 uses 12V on the White wire to the headlight relay and has a diode on the White wire. There is a latch diode in the relay at the coil.

The 1978/79 uses 7V on the Yellow wire to the headlight relay. There is no diode on the Yellow wire and there is no latch diode in the relay at the coil.


XS1100 headlight relay pictures:

On the left is a 1980/81 relay and on the right is a 1978/79 relay.

The1980/81 relay is smaller than the 1978/79 relay and the pinout is different.





XS1100 headlight relays with the covers removed.

On the left is a 1980/81 relay and on the right is a 1978/79 relay.

The 1980/81 relay has an internal latch diode on the coil and the 1978/79 relay does not.

[natemoen]

That's what that big honking thing is!

[TopCatGr58]

Scott,

Why is the yellow wire 7 volts? Can the 78-79 relay handle 12 volts? If so, i was thinking that if it could handle 12 volts, then I/we could use the idiot light output terminal to power the relay?

There are WIRES wrapped around those 4 screws, and they look like on a couple of them that the came from the Stator windings...did you notice the wires around the screws? Clicking on the Alt image will enlarge it for a better view. There is NO dedicated ALT wire/connector on this model.

The ALT guy/shop said they would wire up a trigger wire, but I'm trying to do this myself to document for others how to do it, sorry to be a pain and a novice, but I'm trying to learn. I would prefer to just tap 1 leg of the 3 phases of the mini alt, and not mess with the common wherever it might be!

Ray, only the large shaft/bolt charging connection is labelled with a "B", the other 2 terminals have NO markings on them, because this thing is marketed as a 1 wire device.

I'm a bit pissed at GRAINGER, my B-I-L went there today to get the pulley, but they said they couldn't take CASH?! That store is some 20+ miles away, and they are only open on M-F, not weekends!

SO....it looks like I'll have to order one online, but in the mean time, I'll probably machine one out of some 1" thick aluminum stock I have, but again, I'm wanting to utilize off the shelf items, most folks won't have access to home machining and such.

BTW, I was able to get to the local auto shop with the bike today, hooked up the electrical guys AC generator Pulse counter, but it was a bit difficult to figure out how to read. When I had it idling at about 1100-1200 rpm according to the OEM tach...about 600 on the 4cyl dwell/tach which would be 1200 actual rpm, we got a reading of about 125 hz. So it looks like my calculations with the 6 pole rotor panned out, so we know that the frequency of the OEM ALT is 100hz for 1000 rpm, 200 for 2k, 300 for 3k, etc..

And since the mini alt is also a 6 pole rotor, it should have the same frequency pulse rate when spinning at a 1:1 with the crankshaft.

We're getting close.
T.C.