Author Topic: The $6 Charging System Output Improvement Mod (Read 21690 times)

scottly · « **Reply #50 on:** July 04, 2020, 08:01:59 PM »

Quote from: bryanj on July 04, 2020, 12:49:36 AM

The standard Honda regulator has 3 position
1 full battery voltage to field
2 zero voltage to field
3 reduced voltage to field

The risistor is only in circuit in condition 3

This is incorrect. There are actually two resistors in one, a 10 ohm and a 25 ohm, that share a common connection to 12+. The 25 ohm is connected in series with the 11 ohm regulator coil, and has current flowing whenever the ignition switch is on.
The 10 ohm is connected to the white field wire; in condition 1, full output, there is no current through it, as it has 12v on both ends. In condition 3, the 10 ohms is in series with the 7 ohm field coil, which reduces the field current by dissipating heat in the resistor. In condition 2, the field is connected to ground, so full voltage is applied across the 10 ohm resistor.

dazemc · « **Reply #51 on:** July 04, 2020, 08:23:54 PM »

More efficient would be a way to store that in capacitance rather then waste it on heat dissipation then? What is the max output of AC and could you keep the field coil in a constant on state without wear being an issue? I'm just thinking that there is more efficient DC to DC converters that might be able to bypass the regulator. I don't know I'm just trying to learn more about this.

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scottly · « **Reply #52 on:** July 04, 2020, 08:27:43 PM »

Quote from: dazemc on July 04, 2020, 08:23:54 PM

More efficient would be a way to store that in capacitance

The battery is the storage component of the system.

dazemc · « **Reply #53 on:** July 04, 2020, 08:28:27 PM »

Quote from: scottly on July 04, 2020, 08:27:43 PM

The battery is the storage component of the system.

Oh, duh.

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PeWe · « **Reply #54 on:** July 05, 2020, 03:43:27 AM »

I search for a connector for my rectifier to be built thanks to this thread, maybe 2.

It look as I need to cannibalize a CB750 rectifier to get a connector that fit the main harness.

rotortiller · « **Reply #55 on:** July 05, 2020, 04:29:46 AM »

Quote

My question was about the earlier photo with 14.35V.

Yes PeeWe, as you well know 77 and 78 have no headlight on/off switch which means headlight is on. Since the high beam indicator is off it's on low beam during the measurements. H4 55/60 watt. It also has stock coils and Tytronics ignition.

PeWe · « **Reply #56 on:** July 05, 2020, 04:53:54 AM »

Quote from: rotortiller on July 05, 2020, 04:29:46 AM

Quote
My question was about the earlier photo with 14.35V.

Yes PeeWe, as you well know 77 and 78 have no headlight on/off switch which means headlight is on. Since the high beam indicator is off it's on low beam during the measurements. H4 55/60 watt. It also has stock coils and Tytronics ignition.

Really good working charging system then.
EU bikes have headlight off.

Deltarider · « **Reply #57 on:** July 05, 2020, 04:57:20 AM »

Quote from: PeWe on July 05, 2020, 04:53:54 AM

EU bikes have headlight off.

Thank Goodness for that!!

PeWe · « **Reply #58 on:** July 05, 2020, 05:14:43 AM »

I like the OFF-Parking-Headlight function
https://www.cmsnl.com/honda-cb750k7-four-european-direct-sales_model14391/switch-startkill_35150404003/#.XwHDtLeeyKo

My K6 has this too.
Hi-Lo on left switch.
If battery is weak, parking will make bike visible, especially with LED parking bulb.

rotortiller · « **Reply #59 on:** July 05, 2020, 05:34:10 AM »

PeWe, This is after about 1 minute after using the electric starter to fire it up. It was not quite as good with the old wet cell battery. The odd thing is the way the regulator works, once the rpm is increased to 4 grand and strong the system voltage is now 14.2 volts. I have wondered if a fellow could increase the field voltage a couple of volts with a special booster circuit at idle how much better it could be and still retain reliability. The AGM battery I have has a higher static voltage compared to a wet cell.

Medyo Bastos · « **Reply #60 on:** July 05, 2020, 06:30:08 AM »

What are you calling system voltage? That looks like charging voltage to me which makes sense at 4k.

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FJ40toy · « **Reply #61 on:** July 05, 2020, 06:54:16 AM »

Quote from: PeWe on July 05, 2020, 03:43:27 AM

I search for a connector for my rectifier to be built thanks to this thread, maybe 2.

It look as I need to cannibalize a CB750 rectifier to get a connector that fit the main harness.

PeWe, you can get a kit that has the housings and connectors from http://www.vintageconnections.com
No need to cannibalize a harness for the parts.
I have several kits from them and they are a good quality kit. You will need to order the crimper as well unless you already have one that works with this style connectors.

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PeWe · « **Reply #62 on:** July 05, 2020, 08:02:01 AM »

I checked that site and saw a connector. They claimed I have to change the other connector too, the one attached to the main harness.

It will cost plenty to order from USA in shipping and customs to Europe.

PeWe · « **Reply #63 on:** July 05, 2020, 08:05:32 AM »

Quote from: Medyo Bastos on July 05, 2020, 06:30:08 AM

What are you calling system voltage? That looks like charging voltage to me which makes sense at 4k.

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+1

rotortiller · « **Reply #64 on:** July 05, 2020, 08:15:54 AM »

Quote

What are you calling system voltage?

When every part of the electrical system is seeing and being powered by 14 volts regulated being supplied by the alternator. Electrical energy is supplied by a 14-volt, direct-current system powered by an engine-driven alternator and a 12-volt storage battery.

HondaMan · « **Reply #65 on:** July 05, 2020, 08:18:45 AM »

This mod is best applied to the 500/550 bikes. I have done it before, in the 1990s, when the Schottky power diodes first showed up (and were more than $25 then, which would be $80 now). If they are now just $6, it might be worth turning it into a product for those bikes?
The one thing to remember about this diode architecture is: they do not handle surges well, and they are often limited in PIV rating, so you must "go big" relative to the loads involved. Heck, in 1994 the biggest one I could even get was 10 A rated!

You can also use germanium diodes (like in the early bikes, the twins), which have a 0.3v forward drop. They have become expensive lately, though, as germanium is being sucked up by the supercomputer industry these days for faster chips.

American Locomotive · « **Reply #66 on:** July 05, 2020, 09:10:54 AM »

It's amazing how far "power" electronics have progressed. This $6 Schottky rectifier is rated for 45v, 45A continuous current rating and a 150A surge.

MauiK3 · « **Reply #67 on:** July 05, 2020, 09:16:32 AM »

Sounds like a product is waiting to be made and offered.

Deltarider · « **Reply #68 on:** July 05, 2020, 09:18:49 AM »

Question: are these Schottky diodes being applied elsewhere, meaning: modern bikes? Anyway, it looks like worth experimenting. I await the results with interest.

PeWe · « **Reply #69 on:** July 05, 2020, 10:30:10 AM »

I have ordered 2 just for sure

I'll plan to install it as an extra unit.
If it fails just swap connectors and back with stock.

HondaMan · « **Reply #70 on:** July 05, 2020, 01:51:41 PM »

Quote from: Deltarider on July 05, 2020, 09:18:49 AM

Question: are these Schottky diodes being applied elsewhere, meaning: modern bikes? Anyway, it looks like worth experimenting. I await the results with interest.

Probably not: the ordinary silicon diodes are about $0.02 in quantities of 10,000 now, and the Schottky type is about $0.24 in that quantity. Bean counters force engineers (like me) to "re-evaluate your design" when they see that sort of thing. It has little to do with performance.

American Locomotive · « **Reply #71 on:** July 05, 2020, 05:22:35 PM »

They're most often used in applications where maximum speed efficiency or speed (they work at higher speeds than regular diodes) are very important. Solar systems, electric cars, power supplies, etc...

grcamna2 · « **Reply #72 on:** July 05, 2020, 07:57:23 PM »

Quote from: American Locomotive on July 05, 2020, 05:22:35 PM

They're most often used in applications where maximum speed efficiency or speed (they work at higher speeds than regular diodes) are very important. Solar systems, electric cars, power supplies, etc...

That seems like efficient use of energy.

HondaMan · « **Reply #73 on:** July 05, 2020, 08:50:20 PM »

Quote from: American Locomotive on July 05, 2020, 09:10:54 AM

It's amazing how far "power" electronics have progressed. This $6 Schottky rectifier is rated for 45v, 45A continuous current rating and a 150A surge.

A word of caution, should you decide to make a "product" of it for sale: the open-circuit voltage on the CB750 at 6500+ RPM is slightly over 70v AC. The Achilles Heel of using the Schottky in this situation comes from bikes with corroded connections (often to ground, in the old plug-together connectors used on these bikes) which can intermittently spike to 70v over a bumpy road. My very first Transistor Ignition (circa 1973) did not take this into consideration, and it cost me the power transistors on a friend's poorly-rewired Honda CB750: the transistors I used then were PIV 48v and a loose ground smoked those suckers during a dirt-road ride one day, shorted them dead! My current Transistor Ignition is rated beyond 1000v, haven't suffered any overvoltage failures in this design, even with the nasty ACCEL coils.

American Locomotive · « **Reply #74 on:** July 05, 2020, 09:22:39 PM »

That is something I considered, but I'm not sure how big of an issue it'd really be. Schottky diodes tend to be very forgiving if you exceed their voltage rating. They don't typically short, they just gradually start conducting in the reverse direction and dump that as heat. So basically if the connection from the rectifier to the battery were to momentarily break, the worst would happen is you'd get a slight bit of extra heat in your heatsink

If someone were to make this a "product" (not me, I have no intention to do that), a simple solution would be to add a 40v TVS-diode (or equivalent) across the output. That way any potential transients would get clamped and harmlessly turned into heat. Not sure if that'd really be any better than just letting the rectifier deal with it on its own, but it might make some sleep better at night.

I guess I could be a guinea-pig and test it tomorrow and see what happens. Worst case I'm out $6

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Author Topic: The $6 Charging System Output Improvement Mod (Read 21690 times)