Topic: The $6 Charging System Output Improvement Mod

[grcamna2]

'A L' :American Locomotive.,
Do you know of a better way to attach the Schottky rectifier to the heat sink besides the clip ? Can it be surrounded by a small bracket or something? I doubt there's any area of it that I could drill through..
The reg/rect units traditionally like a solid connection to the heat sink so the transfer of heat is complete.

[MauiK3]

Would it attach with a thin coating of an epoxy with a gentle clamp to assure it's down on the heat sink?
Gap filling super glue?
How much heat is expected?

[FJ40toy]

Can try thermally conductive adhesive for the heatsink. It works well, but not sure how it would hold up to vibrations from the bike. From my experience it is used on electronic equipment that is stationary such as networking equipment.

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[Deltarider]

  I have never had a CB750 that ever had a charging problem

Neither have I.

nor have i...not even with 550s

Nor have I... not with my CB500 and I run a 55/60 Watts H4, 3Ω coils and a transistor ignition (which draws just a little extra). After every ride I return with a better charged battery than I left with. But I find your experiment very, very interesting. Forgive me my ignorance, but seen the high charging rates, I take it the regulator was bypassed?

[PeWe]

Good improvement!  More efficient charging of the stock stuff for a few $ more.

Riding longer time at lower rpm will not charge much, especially not with headlight on, frequent use of blinkers and brake light.

I see how it works after I mounted a LED voltage meter between gauges last year

My K2 need ground cabling improvement to rectifier and front inside headlight direct from battery ( - ), voltage drops.

[Medyo Bastos]

'A L' :American Locomotive.,
Do you know of a better way to attach the Schottky rectifier to the heat sink besides the clip ? Can it be surrounded by a small bracket or something? I doubt there's any area of it that I could drill through..
The reg/rect units traditionally like a solid connection to the heat sink so the transfer of heat is complete.

CPU thermal paste should be fine


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[grcamna2]

'A L' :American Locomotive.,
Do you know of a better way to attach the Schottky rectifier to the heat sink besides the clip ? Can it be surrounded by a small bracket or something? I doubt there's any area of it that I could drill through..
The reg/rect units traditionally like a solid connection to the heat sink so the transfer of heat is complete.

CPU thermal paste should be fine


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Thermal paste,is that adhesive ? I've used it for the heat sink on a computer CPU

[FJ40toy]

I don't think you want thermal paste for CPUs. Those have a clamp mechanism to hold the fan on. You want a thermally conductive epoxy or tape.
This will adhere the component to the heatsink.

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[American Locomotive]

Yes, I am using thermal compound between the rectifier and the heatsink. You can use thermal epoxy, a thermal pad or anything else thermally conductive.

The clip could also be replaced with any kind of mounting mechanism you want. You can use screws and a clamp, epoxy, or anything really. I was going to do a clamp but didn't have any small screws handy. Thermal paste and pads will require a retention mechanism, epoxy will not.

Nor have I... not with my CB500 and I run a 55/60 Watts H4, 3Ω coils and a transistor ignition (which draws just a little extra). After every ride I return with a better charged battery than I left with. But I find your experiment very, very interesting. Forgive me my ignorance, but seen the high charging rates, I take it the regulator was bypassed?

Regulator is not bypassed. It's set to 14.2v, and I have a brand new healthy battery that will accept a lot of charge if I purposely run it down some.

Like I said, this mod won't make a difference for many people, but for those running extras like heated hand grips and have some issues maintaining charge - this is a cheap way to squeeze a bit more out.

Plus, 20w less wasted electricity is 0.027 HP more at the crank - which means a faster bike

[Medyo Bastos]

Id recommend tinning your conductors before soldering them in place.


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[grcamna2]

Thermal epoxy to glue the unit to the heat sink,that sounds like the best solution to me.Does thermal epoxy allow heat(I'm just learning here..)to transfer directly through it to the heat sink,no loss of transmission ?

[MauiK3]

How may this work with a solid state voltage regulator?

[FJ40toy]

Thermal epoxy to glue the unit to the heat sink,that sounds like the best solution to me.Does thermal epoxy allow heat(I'm just learning here..)to transfer directly through it to the heat sink,no loss of transmission ?

Yes. It serves two purposes, one to affix the heatsink to the chip or device, and second to conduct heat to the heat sink from the device or chip.
It works well.

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[dazemc]

I am very excited to try synchronous rectification using MOSFETs. I had never heard of such a rectifier before but it does look like something I am familiar with. A Dickson MOSFET charge pump, which makes me wonder if you could produce an AC to DC charge pump. This would give you the benefit of removing the regulator at about a 90-95% efficiency. I still don't quite understand how the original rectifier works but I found this diagram. So it looks like it's using two transistors, two diodes, 3 resistors and one zener diode. Attached is a write up that was with the diagram. So to me it appears to ground out the field coil to achieve a set voltage. Could the field coil just be relayed to constantly be on? If not, there has got to be a way to control the field coil switching using MOSFETs as well. http://cloud.tapatalk.com/s/5effce336f411/VoltRegExciteField%20%281%29.doc

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[dazemc]

Also, if Honda rectifiers are similar...... Do they have 9 diodes too? Would explain the horrendous voltage drop.


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[American Locomotive]

I am very excited to try synchronous rectification using MOSFETs. I had never heard of such a rectifier before but it does look like something I am familiar with. A Dickson MOSFET charge pump, which makes me wonder if you could produce an AC to DC charge pump. This would give you the benefit of removing the regulator at about a 90-95% efficiency. I still don't quite understand how the original rectifier works but I found this diagram. So it looks like it's using two transistors, two diodes, 3 resistors and one zener diode. Attached is a write up that was with the diagram. So to me it appears to ground out the field coil to achieve a set voltage. Could the field coil just be relayed to constantly be on? If not, there has got to be a way to control the field coil switching using MOSFETs as well.

Analog Devices makes the synchronous rectification chip - they call it the "ideal diode bridge controller". It analyzes the incoming AC signal and properly sequences and drives the MOSFETs (and it has built in charge pumps). It works from DC to over 600 Hz AC. I might spin up a board for fun.

So the stock regulator is just a set of contacts that get opened by a magnetic coil. When the desired voltage is achieved, the contacts open up and the field coil is turned off. Of course this cycle occurs very rapidly near the regulated voltage setting. The biggest issue with the stock regulator is that there's a big power resistor on it that's burning at least 5 watts of power, if not more.

How may this work with a solid state voltage regulator?

If you have a separate regulator and rectifier you can do it. If you have one of the combination regulator-rectifiers, it will not work. Well it won't work without going back to a separate regulator.

Also, if Honda rectifiers are similar...... Do they have 9 diodes too? Would explain the horrendous voltage drop.

They should only have 6 diodes internally.

[bryanj]

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

[PeWe]

My rectifier was heavily corroded under the ground connection, brushed it and added an extra ground wire to battery -.

This  FUS45-0045B rectifier used here is the 20A version?
Is that enough for eventual spikes?
The old rectifier can still sit, just swap connector if it will give up, old Honda back in.

A connector housing needed.
Stock look like this. Fixed surfaces and additional ground wire. There is an isolating washer at top, I'm sure it will quick go bad if lost.

[American Locomotive]

My rectifier was heavily corroded under the ground connection, brushed it and added an extra ground wire to battery -.

This  FUS45-0045B rectifier used here is the 20A version?
Is that enough for eventual spikes?
The old rectifier can still sit, just swap connector if it will give up, old Honda back in.

A connector housing needed.

The FUS45-0045B is rated at 20A per diode (this means one AC phase can feed up to 20A), but in normal operation with all 3 phases going, it's rated for up to 45A continuous. It has a 150A surge current capability.

For the connector, I cut the plug off the original, but left enough wire so that I could reattach it later if needed. I understand some may not be willing to cut up an original factory part though. There are tons of new aftermarket rectifiers for sale for these bikes with the correct plug, so someone has to be making it. It's just a matter of identifying the type of plug.

[rotortiller]

My stock CB750 system is pictured. As you can see it is powering the complete electrical system at under 1800rpm. The coming-in rpm of my alternator is even lower. (the rpm at which the alternator powers everything and power flows into the battery instead of out). If you have an modern efficient AGM battery coming in rpm will be lower over old school wet cell battery. The stock CB 750 , it uses a full wave 3 phase 6 diode rectifier. Maybe the subject mod can improve my situation, however  it's fine in my situation. Options are also available for LEDs freeing up additional head room and adding lighting lifespan. Six bucks is a pretty cheap way to add performance or replace a toasted component.

[American Locomotive]

Yup, like I said many times: If you have a stock bike with a stock electrical system, this mod will not do particularly much for you. It provides extra current in low RPM situations and about 20w total extra charging system power. Not earth shattering by any means, but it's a nice bump for less cost than a meal at Burger King. I suppose if you have a failed/toasted stock rectifier, there would be no reason to NOT do this mod, unless you need your bike to be original as possible.

As far as rectifier terminology goes: Any full-wave rectifier is a "bridge" rectifier. In the case of these bikes, the exact term would be a "Polyphase diode bridge rectifier"

[PeWe]

OK charging with headlight ON?
H4 55/60W

That"s the weakness this cheap mod hopefully can fix.
This is the law here and safety to be seen.

[American Locomotive]

OK charging with headlight ON?
H4 55/60W

That"s the weakness this cheap mod hopefully can fix.
This is the law here and safety to be seen.

My bike with the stock regulator will have a slight battery discharge at idle and high-beam on. With the schottky, it's a slight battery charge at idle. But of course, that it just with my particular bike, my battery and my electronics.

[PeWe]

My question was about the earlier photo with 14.35V.

I found a seller in UK with low shipping to me. Order done!
https://www.ebay.co.uk/itm/192960004000

Next is to find heat transfer paste, cooling plate to attach it on.
I'll fixate it with an alu plate with 2 holes for screws tightened into the alu plate it sit on as cooler.

I saw heat transfer glue, not cheap.
Connector housing  for additional mount and swap connector plan B 

[Alan F.]

For heat transfer compound ask around to friends that build computers or dabble in electronics, someone will be able to spare some.