Honda Twins banner

1 - 20 of 20 Posts

·
Registered
Joined
·
101 Posts
Discussion Starter · #1 ·
My CB450 K1 doesn't have a regulator fitted. I'm putting in a new gel battery.

I know the theory behind having a regulator, but how wise is it to continue running without one? Why was it omitted in the first place?

If essential, I'll probably upgrade to a combined regulator/rectifier, (suggestions as to which would be welcome) but meantime, I have an original regulator from a CB750 K2 sitting here; could I put that in temporarily?

Thanks for thoughts.

Sean
 

·
Premium Member
Joined
·
2,838 Posts
The alternator puts out AC voltage up to around 70 volts. The rectifier converts this into DC voltage and the regulator regulates the voltage to around 12 volts. Without them you are just running off the battery until it dies, no charging will take place.

I don't know why the 750 R/R wouldn't work but I have never seen one. I added a Kohler R/R on my 450 to replace the separate R/R originally on the bike.
 
  • Like
Reactions: Gixxer-18

·
Registered
Joined
·
2,561 Posts
While a newer R/R is an improvement, since it will also replace the inefficient selenium rectifier, are you sure you don't have a regulator? It doesn't look like most, but like #1 on this:

 

·
Registered
Joined
·
101 Posts
Discussion Starter · #5 ·
Jim, Maybe I wasn't clear; it is charging - there is a rectifier, but no regulator. So my concern is that even when fully the battery is fully charged the alternator will continue to send full current.

Rick, Pretty sure. I have wiring diagrams (from FSM & Clymer) for a "General Export (Not in US)" model that doesn't show a rectifier. I'll have a look at that Oregon MC one, thanks.

Seems very odd to me to leave it out of just one model!

Sean

CB 450 (General Export) Wiring Diagram.jpg
 

·
Premium Member
Joined
·
2,838 Posts
For what it was designed for (lead acid battery) it doesn't need a regulator. Charging cycle for a gel battery is completely different. You could add a regulator but I don't know if the alternator will support it. Your alternator may or may not have less output so a regulator is not needed. Just guessing on my part, there are others on here that might provide a correct answer.
 

·
Registered
Joined
·
2,561 Posts
If the alternator output is the same as all the others, it will make a flooded lead-acid battery lose water faster; that just makes for more checks of the levels, and more top-ups. A quality regulator will not reduce the overall charge level, because the diodes in it will have lower Voltage drop than a new selenium rectifier, and a LOT lower drop than an old one. If, however, the OP has the silicon rectifier, as was found in the later models, a modern regulator could reduce charge rates by a very small amount.

A quality modern regulator, like the one I linked (I know there are cheaper ones) are series-pass type, which just stop conducting current from the stator when the battery is full. The stock regulator, and many of the cheaper after-market ones, are shunt regulators, which short the stator; the stator current (and load on the engine) actually increases when the battery is full with these, but they don't need as large a heat sink, and are cheaper to make. Whichever type you use, one is necessary if you use a sealed or AGM battery, or the battery will out-gas when it reaches full charge, which damages it.
 

·
Registered
Joined
·
3,537 Posts
Sean, it is surprising Honda would omit the regulator. They must have been trying to make a price point on that model. I wonder what other differences there is on your bike. Please post some pictures.
If you are trying to upgrade the charging system then get a modern combination regulator/ rectifier. They are more efficenct in terms of current loss. It is in the range of 10% better. I know the CB750 had a field effect alternator. I don't know if the regulator would work.
 

·
Registered
Joined
·
308 Posts
For an old bike, fitting an adjustable regulator may not be a bad idea. The output voltage can be adjusted on them. You do not want it to be over 14.5V (that is where most batteries will start to boil). If it were constantly around 12-13V, that would be perfect for battery life, but old charging systems were simply not that capable, and you have to charge with more to offset that (even modern bikes do, because more powerful generators also take more engine power to work). Perhaps the old CB450 did not even reach 14.5V, so Honda decided it does not need an additional regulator - still, I'd rather use one in any case.

On an adjustable regulator, you can set it as low as possible, so that the battery always stays charged. The problem on old bikes is that riding in low revs (f.e. around the city) will not even produce enough power to charge the battery (but we are lucky to have kick starters). I imagine the CB450 needs at least 3000rpm before it produces more power than it consumes to run - but back in it's day, you did not need to have the headlight on constantly. Changing out all the classic bulbs with modern LEDs that fit in the same socket can help a lot.
 

·
Registered
Joined
·
3,108 Posts
Honda didn't omit the regulator, they just didn't have one on the earlier models. They used the "balanced load" principle for charging. Part of the alternator coils were in the circuit for daytime running and extra coils were switched on via the light switch. The British bikes used a system where the alternator was wired to put out full output all the time and the excess current was shunted to ground via a zener diode. The Japanese elected to save a few yen and go with switched alternator coils using the resistance of the battery as a regulating device. The newer rectifier/ regulators are the way to go, lots more efficient than the old parts, more watts left over to charge the bat.
 

·
Registered
Joined
·
2,561 Posts
For an old bike, fitting an adjustable regulator may not be a bad idea. The output voltage can be adjusted on them. You do not want it to be over 14.5V (that is where most batteries will start to boil). If it were constantly around 12-13V, that would be perfect for battery life, but old charging systems were simply not that capable, and you have to charge with more to offset that (even modern bikes do, because more powerful generators also take more engine power to work). Perhaps the old CB450 did not even reach 14.5V, so Honda decided it does not need an additional regulator - still, I'd rather use one in any case.
until a common lead-acid battery reaches 12.9V, it is not charging at all. A useful charge rate is not reached until the battery is above 13.5V, or you will not recover the charge used in a single electric start in a reasonable time. The 450 charging system could easily exceed 14.5V if you keep it above 3000rpm; the break-even point is about 1500rpm with the lights off, and about 1800rpm lights on.
 

·
Registered
Joined
·
308 Posts
until a common lead-acid battery reaches 12.9V, it is not charging at all. A useful charge rate is not reached until the battery is above 13.5V, or you will not recover the charge used in a single electric start in a reasonable time. The 450 charging system could easily exceed 14.5V if you keep it above 3000rpm; the break-even point is about 1500rpm with the lights off, and about 1800rpm lights on.
Then I find it hard to believe they have not used some sort of a regulator. No 12V acid battery can handle higher voltages.
I am not an expert on this stuff, but I am quite certain the voltage is not the only determining factor in how fast a battery charges - some generator may charge a battery just as fast at a low voltage (with higher current?).

Edit: Mike in Idaho explained how they did it (I did not see it before).
 

·
Registered
Joined
·
2,561 Posts
Then I find it hard to believe they have not used some sort of a regulator. No 12V acid battery can handle higher voltages.
I am not an expert on this stuff, but I am quite certain the voltage is not the only determining factor in how fast a battery charges - some generator may charge a battery just as fast at a low voltage (with higher current?).

Edit: Mike in Idaho explained how they did it (I did not see it before).
A lead-acid battery begins to bubble, due to hydrolysis, when the cell Voltage exceeds about 2.4V (that's close to 14.5V in a 12V battery). How fast depends on how much over that Voltage it gets; it's only separating water from the electrolyte, so if you keep a close check on it, you can keep the damage to a minimum. The limited power of the 450 charging system prevents it going much above this, but on an extended ride it very well may, especially if you use lower power lamps, like LEDs. Because of the nature of the battery, however, the charge rate, in Amperes, is largely determined by the Voltage applied, so to get to the 'ideal' 1/10C charge rate at close to full charge, the Voltage needs to be above about 2.3V per cell, or 13.8V; BTW, C is the capacity in Ah, so 1/10C for our stock 12Ah battery would be 1.2A for every hour of charge.

Charging is kind of complicated, but this set of curves can give some insight:https://forums.sailboatowners.com/index.php?attachments/image_3535-png.119206/
Note that, if you keep the charging Voltage below about 13.5V, it will take a very long time to reach full charge. Also note that you should never take a lead-acid battery below about 30-40% state of charge, or it won't last very long.
 

·
Registered
Joined
·
308 Posts
Thanks, that makes it a bit more clear.

I've had an old 77' Guzzi V35. They all had the same generators (like the big 1000cc models), but the small ones worked in higher revs so it made lots of power. I had a voltmeter on it, and I also mounted an adjustable regulator from Bosch, and set it from 14.5V to 13.5V. It made the battery cooler (it actually got warm when riding at 14.5V).
It rarely dropped under when I had a new battery (it was my only means of transport as a student back then, and sadly the battery got old and I was constantly push-starting it from then on).
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #15 ·
This has been great info; thanks to all.

I researched a bit more and in a manual called "Honda Motorcycles Electrical Systems Service Manual" (a great read if your confined to bed for a week one day) I found exact confirmation of what Mike explained.

Extract from HMESSM.jpg

Looking at the charging current, which can vary anywhere between 1 & 4A at 3000 RPM and 1.6 & 5A at 5000, I will be fitting a regulator ASAP - I have a reg/rectifier combo ordered (equivalent to Koehler 25-755-03 as per http://www.hondatwins.net/forums/50-electrical-discussion/14014-cheap-regulator-rectifier-upgrade.html.

Will see how it goes.
 

·
Registered
Joined
·
2,561 Posts
If you upgrade to an AGM battery, which I heartily recommend, you will need a good regulator.
 

·
Premium Member
Joined
·
3,003 Posts
Jumping into this thread late, the UK specification CB175s didn't have a regulator, just the rectifier, as shown in the wiring diagram in the FSM.

I often wonder if this is why my (new in 1973) CB175 used to eat tail light bulbs on a regular basis. Never had a problem with the battery over charging though.

us175.JPG

uk175.JPG
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #18 ·
Yes, Richard, I though it somehwat odd too.

According to the Clymer I have that all the 5-speed models, except the one "General Export - not US", have a regulator.
 

·
Registered
Joined
·
48 Posts
Am working on the 1972 CL450 K5 project bike.

Where is the regulator mounted? Or maybe I should be asking where the regulator should be mounted?
 

·
Registered
Joined
·
2,561 Posts
Am working on the 1972 CL450 K5 project bike.

Where is the regulator mounted? Or maybe I should be asking where the regulator should be mounted?
If you mean the stock regulator, it attaches to the bottom of the air cleaner crossover tube.
 
1 - 20 of 20 Posts
Top