Topic: Regulators and Rectifiers

[TwoTired]

but I would think you could avoid the 1 HP loss above 2k RPM.

I'm curious, just how inefficient do you think the charging system is?

1HP = 745 watts.

[Bailgang]

Electrical topics is something I have very limited knowledge of so please excuse the ignorance of my question but if there is indeed a HP increase by using this setup then where is that increase coming from? Is it from a reg/rect  that has tighter control OR from the more efficient lithium iron battery that demands tighter voltage control? The reason I ask is because it's still based off the old stator/alternator as before. Would a bike that's still using an old style lead acid battery see any benefit? Pleas understand I'm not debating this, I'm just asking.

[TwoTired]

When you look at the mass (weight) and compare the maximum output to other lighter or equal mass alternators available, well it is kinda piss poor. It's not simply the horsepower to watt ratio- the general POS ratio factors in well to the topic.

 What exactly are you comparing to? 
  From Wiki:
"Efficiency of automotive alternators is limited by fan cooling loss, bearing loss, iron loss, copper loss, and the voltage drop in the diode bridges. At partial load efficiency is between 50-62% depending on the size of alternator and varies with alternator speed."

All but one model of SOHC4 has all the windings (with their associated weight) outside the rotating mass.  The rotating mass only uses significant HP to change the rotational speed, overcoming inertial effects.  So, it is only acceleration where there is opportunity to take some significant HP from the crankshaft.

The 750's alternator produces 210 watts (peak alternator RPM).   To insist that it takes 1HP to produce this during cruise, infers that the alternator is only 28% efficient.  I find this hard to believe, from a simple assertion.  What data is there to demonstrate this?

[KurtK]

Is there any way you could put a 750 stator in a 500 to increase the output?  Would it fit?

[TwoTired]

Electrical topics is something I have very limited knowledge of so please excuse the ignorance of my question but if there is indeed a HP increase by using this setup then where is that increase coming from?

This is a very good question.  The "increases" have not been quantified, only lauded.  One could argue that 0.00001% is more than nothing.  But, when using a total quantity of 150 or 210, the actual percentage improvement is nearly lost in the noise.

Is it from a reg/rect  that has tighter control OR from the more efficient lithium iron battery that demands tighter voltage control? The reason I ask is because it's still based off the old stator/alternator as before.

That is the message I was trying to convey.  If you have changed something in the system (like perhaps the battery) that requires an associative change in the regulator, then maybe yes.  However, I maintain that unless there is a voltage adjustment available to tailor the regulator to LiFePo4 technology, it is only a partial step toward "better".  Further, lithium technology requires a low voltage cutoff to protect the battery from excessive depletion damage.  And, nothing presented here provides that automatically.

Would a bike that's still using an old style lead acid battery see any benefit?

In my educated opinion, no.   (But, it is cheap for an experimenter!) 

Cheers,

[KurtK]

Two Tired ...in your opinion is it worth it to remove the 500 windings and go buy the 750 windings?  There is a motorcycle junk yard close by I am sure I could get one.  How much power would I lose?

[TwoTired]

Two Tired ...in your opinion is it worth it to remove the 500 windings and go buy the 750 windings?  There is a motorcycle junk yard close by I am sure I could get one.  How much power would I lose?

I think physical fit is a major obstacle to this approach.  Simple parts swapping is not an option.  There will be some machining, and perhaps welding needed to adapt the parts noted.

Cheers,

[Kickstart]

but I would think you could avoid the 1 HP loss above 2k RPM.

I'm curious, just how inefficient do you think the charging system is?

1HP = 745 watts.

I was going off of HondaMan's post.  But good point on that... it doesn't make sense how increasing the alternator output by 100 watts or so (using different windings or rotor) could lead to that much HP loss.  Maybe the loss is compounded when calculating the BHP loss (but i would think it would be the other way around)

Still, there will be some additional drag on the engine if one was to modify the alternator to produce more output... and I was wondering if this could be reduced or eliminated by using a more efficient rectifier/regulator system.  i.e., using the CB750A field coil with Schottky diode bridges and a solid state rectifier - would this produce more power without significantly increasing the load on the engine?

[TwoTired]

Still, there will be some additional drag on the engine if one was to modify the alternator to produce more output...

More peak output?  More output for cruise?  Or, more output at idle?  How much power do you need for normal driving about?

If the bike only needs 120 watts to operate after getting the battery back to full charge, even a 400 watt alternator isn't going to be of benefit.  As it will only make 120 watts most of the time.  During battery recharge, it will make max power when revved up, recharging the battery quicker.
Depending on the alternator design, there will be a marginal increase at idle speed.  (400/3 = 133-ish watts)

If I recall, the A stator makes 230 W at 5000 rather than the standard 210. (Need a spec here.)  At idle, it makes about 1/3 of that, say, 75 watts.  The Schottky diodes MAY increase that by a couple watts due to increased efficiency, but it still won't be the 120 needed to run the bike in stock electrical configuration.
Hey, I'm just spit-balling here, as I have no solid numbers with which to make a firm analysis.

and I was wondering if this could be reduced or eliminated by using a more efficient rectifier/regulator system.  i.e., using the CB750A field coil with Schottky diode bridges and a solid state rectifier - would this produce more power without significantly increasing the load on the engine?

It sounds like you are looking to force a solution into an unknown or undefined problem.  Just how much power do you need to make?  And at what RPM?  And, just how much HP are you trying to save?  1/2 a HP?  If so, I'll ask you why 1/2 a HP is so important for a 40 year old machine?

Cheers,

[Kickstart]

Every now and then I get a question along the lines of why do you want to bother doing "X" on a 40 year old bike. 
Because I want to.  That's really the only reason I need.

I've developed a passion for these bikes.  I really enjoy tinkering with them almost as much as riding them.  I also really like the idea of maximizing their performance.

Do I really need to bore out the cylinders, do I really need to drill extra oil holes in the cam towers, do I really need to advance the cam timing, etc..... nope, but I love doing it.  I love learning about these bikes and I get a lot of satisfaction out of making improvements while still maintaining the style and character of the bike.... even if these improvements are hardly noticeable.

I think it would be cool if I could upgrade the alternator to:
A) Maintain the battery voltage at idle
B) Support some more accessories (phone charger and fog lights)
C) Doing A and B above without losing HP at cruising speeds.

[Bailgang]

Every now and then I get a question along the lines of why do you want to bother doing "X" on a 40 year old bike. 
Because I want to.  That's really the only reason I need.

I've developed a passion for these bikes.  I really enjoy tinkering with them almost as much as riding them.  I also really like the idea of maximizing their performance.

Do I really need to bore out the cylinders, do I really need to drill extra oil holes in the cam towers, do I really need to advance the cam timing, etc..... nope, but I love doing it.  I love learning about these bikes and I get a lot of satisfaction out of making improvements while still maintaining the style and character of the bike.... even if these improvements are hardly noticeable.

+1
I can't argue with that. There's no way I could ever get my 550 to run as strong as my kids cbr600 and still have a reliable bike but that doesn't stop me from trying. Even the computer I'm using now is tweaked, the cpu is overclocked so is the video card, it's just my nature. I can't keep from messing with stuff.

[Jerry Rxman Griffin aka MuthaF'er]

I believe the A is 290.

[Kickstart]

I believe the A is 290.

I think I read in Hondaman's book that it also draws more power though... so the net is less than 290, but still more than the stock K.

Things are buzzing on the other thread that Rotortiller posted a link for:
http://forums.sohc4.net/index.php?topic=117735.0

I'm not looking for a modified cover though... I would like it to look like nothing's changed from the outside, and not have to make any changes to the rotor. 

Maybe it's possible to re-wind the alternator windings combined with using the A field coil.  Not sure if that would be enough to make the magic 3 X 120 watts that TwoTired implied would be required to keep the battery from draining at idle.

[Jerry Rxman Griffin aka MuthaF'er]

Why rewind?! Just use one from the A. You'd probably need to upgrade and use the A reg/rect unit also or go with an Electrosport RR240. They tell me their combo unit will handle the extra juice of the A. The A also has some double wiring for the extra load but I do not remember which piece, probably the reg/rect, which go into the multi-connector so it has extra prongs. I have the parts and plan on playing with this one day due to the 3ohm coils and the Dyna III sucking my power down but I used a NOS harness on the restore, a new sub-harness and all the other connectors got replaced. That and the Dyna 2000 plus the RR240 I upgraded to seem to have me up to that magical 14.5V now so it's a back burner project for my next build.