CB350 overcharging battery?

F

fairfield

New Member
I've been working on this bike, just put in a new battery and it starts right up. Had some trouble keeping a charge like most CB350s so I strapped a voltmeter on the tank, went for a ride. I'm reading 13 to 14.5 V when between 3000 - 7000 RPM. Good. When I open it wide, it climbs to 15.3 V. It seems to stop there as though the Regulator was working. Is this normal? I thought 12.6V batteries should only see up to 14.5V before starting to boil and gas... Could I be drying out my battery?

Any help would be appreciated.
 
Measure the AC current directly from the stator plug and see if it's higher than 15.3V. If it is, then your RR is working.
 
15.3V is too high. Anything above 14.6 is abnormal, and anything above 14.2 will damage an AGM battery.
 
fairfield said:
I've been working on this bike, just put in a new battery and it starts right up. Had some trouble keeping a charge like most CB350s so I strapped a voltmeter on the tank, went for a ride. I'm reading 13 to 14.5 V when between 3000 - 7000 RPM. Good. When I open it wide, it climbs to 15.3 V. It seems to stop there as though the Regulator was working. Is this normal? I thought 12.6V batteries should only see up to 14.5V before starting to boil and gas... Could I be drying out my battery?

Any help would be appreciated.
Click to expand...

I would say the Rectifier unit is bad. It's supposed to clip the DC-Voltage at 14.6v max (with deflection from 12 - 13.# at idle to 14.6 Max)

I know Rick's Electrics makes a replacement for most bikes, including the CB350.
http://www.ricksmotorsportelectrics.com/

and have used their units in the past on a number of Japanese & European bikes.

You can buy them direct, or anyone with a Western Power Sports, Tucker Rocky, or Parts Unilimited Account should have access to them.

-=Tom
 
Regulator regulates voltage, rectifier converts from AC to DC.
I would fit a newer combined unit.
I've seen up to 17V @ 11,000 rpm on CB360's with faulty rectifier (some AC getting through?)
 
crazypj said:
Regulator regulates voltage, rectifier converts from AC to DC.
I would fit a newer combined unit.
I've seen up to 17V @ 11,000 rpm on CB360's with faulty rectifier (some AC getting through?)
Click to expand...

Rectifier circuit also clips the voltage at 14.6vDC +/- (usually) not the Regulator in most modern units.

If the AC Regulator Circuit fails, you'll typically just blow all your bulbs.

The AC Voltage from the stator puts out quite a bit of voltage (30~50 volts depending on RPM) which the rectifier unit converts to DC Voltage and then clips to a usable level for the battery so the acid doesn't boil (pretty much anything over 15vDC)

It involves more complicated math and electrical engineering than I ever cared to learn, since all I ever need to know is "Module is bad, replace" and move on.

But again the point is moot, since both the Regulator and Rectifier circuits are embedded in one solid box anymore :)

-=Tom
 
Rectifier doesn't 'clip-voltage' ?
There are losses in conversion which turn into heat, about 48% of AC input voltage 'comes out' as DC (half of each +/- wave)

The system your probably referring to is known as 'load balanced' and is designed around a specific load (lights, etc)
If a bulb in the circuit fails, the rest usually burns out pretty quick.
If the wrong wattage bubs are fitted the lights will be dim and horn/brake light probably wont work except at max rpm
The ignition is almost always some sort of self generated magneto, a separate set of windings totally independent of lighting/charging system
Voltage is also 'clipped' on modern circuits by shunting current back to alternator, fully charged battery in good condition will only give about 4~7vAC at alternator leads when everything is connected up correctly
 
People seem to mix these up quite a bit. The rectifier is simply a full wave diode bridge, exactly like the ones found in many power supplies. Very simply, it's used to convert AC voltage to DC. It has nothing to do with clipping.

The regulator is responsible for regulating the voltage under a certain voltage. The bulbs can take the 15.3V. I'm more worried about the boiling acid under my ass.

I'll check connections. I noticed the regulator senses battery voltage through the fuse, key switch and a few connectors. Lot's of things can happen through all those old contacts. Perhaps all the grime is dropping close to 1V, which would explain why the regulator seems to turn on at 15.3V...

Why not have the regulator closer to the battery?

I saw mention of using a Shindengen SH232-12 on another forum... anybody have experience with replacements other than $100 units?
 
Here's a curve ball...

I had overlooked one of the CB350 service manuals. I found this... see attachment.

Don't you love how they call it the pointless regulator? It says the regulator will maintain the voltage around 15.5V when at high rpm. Apparently, so long as temperature and electrolyte levels are monitored, a lead-acid battery can take up to 16V. Not true for AGM or gel cell batteries.
 

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Absolutely correct about that voltage sensor wire. That wire is often 1v or more less than battery voltage and the regulator allows overcharging. Check voltage on that line as it enters the R/R and it's measurably less than at the battery, that is the issue.
 
The regulator is nothing more than an encapsulated zener diode, as 'loved' by all British bike owners with Lucas electrics
(personally, I've never had issues with Lucas zener diodes)
The connector tab breaks off because of vibration rather than the unit failing electrically (either way, you have to get a new one though :( )
 
I think I remember reading that the regulator is an SCR. Wouldn't a zener regulator only have 2 terminals?

Anyone know a method of testing it on a bench? considering the 3 terminals: battery +, alternator winding and ground? I'm guessing the battery + is sensed and the winding is shorted when over the trip point.

I'll definitely check the voltage at the regulator input. Is there a reason not to sense directly off the fuse instead of going through 4 feet of wire and 1/2 dozen connectors?
 
New ones (~1980>) are SCR's
The only thing I've reaqd on testing requires variable DC power supply.
Never been in a shop that has one, it's something that either works or doesn't.
I f it's hitting 15V it's OK with stock battery and reasonable with any non-sealed lead acid battery, you just check fluid level every few hundred miles until you know how long you can leave it before topping up.
If your using a smaller sealed battery, it's probably safer to swap for a more modern one.
I usually use Honda CB/CM 400 but Kawasaki 250 uses same rec/reg (but with different wiring colours)and I've used Suzuki 'Intruder' simply because it fitted where I wanted (and I understand Suzuki wiring better than Kawasaki ;D )
You can pick one up for about $20~$30, sometimes less on e-bay
 
AlphaDogChoppers said:
15.3V is too high. Anything above 14.6 is abnormal, and anything above 14.2 will damage an AGM battery.
Click to expand...

Of course it is... Your always the final word.

15v is and has been a nice #. And has always worked well.
 
Original style Lucas Zeners had a single connetcor and grounded through the mounting bolt into teh heat sink IIRC.
 
Yep
pretty sure it it only 'regulated' one of the two output leads?
Been a long time since I 'played' with them (mid 70's ;D )
 
The voltage drop isn't so bad. 300mV at 5000 rpm, 450mV at 3000 rpm.

I wasn't getting as high of a voltage reading though. 12.8V at 5000 rpm, but the bike was cold as the test was indoors.
 
Louie,
Why is it that you can't disagree with someone without being a prick about it?

Grow the fuck up!
 
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