Topic: Charging Problem

[bryanj]

Those led indicators being cheap can be inaccurate, 15v if it really is is a little high but a lead acid can take that as long as you keep it topped up. The original charging system on the Hondas is far too crude for the modern LION batteries but SOME of the better electronic replacement regulators do smooth out the peaks.
Most car alternators are regulated at 14.2 to 14.6 volts

[The Lone Builder]

It’s a gel battery.

I managed to keep the light green, meaning somewhere between 11,8 and 15,2,  by judicious use of rpm and my headlight switch. Not great for the switch,I know, but hopefully only for a short period.

The replacement regulator is due on Sat.

[grcamna2]

It’s a gel battery.

I managed to keep the light green, meaning somewhere between 11,8 and 15,2,  by judicious use of rpm and my headlight switch. Not great for the switch,I know, but hopefully only for a short period.

The replacement regulator is due on Sat.

Which style/type reg/rect did you decide on ?

[The Lone Builder]

It’s a used OEM part. Externally looks good so hopefully good on the inside too.

[bryanj]

They are usually ok

[HondaMan]

About the only thing I've seen 'bad' on a used regulator is: a slight white powder on the upper 2 contacts of the relay inside. This is a corrosion that starts when the bike (regulator) is parked for a long time after being used. It polishes off with some paper wiped between the contacts OK. If it isn't removed and the regulator is just installed, it will eventually burn itself away, but may have a few hours of lower-charge performance while it does.

The way Honda designed it, the regulator has silver contacts that self-heal with normal use. And, if the coil ever breaks its wire and becomes 'open' then the worst that will happen is an overcharged battery (usually approaching 16 volts after a long day's ride). Not a bad design at all.

[The Lone Builder]

Insult to injury! My part has been returned to sender!!

Does anyone know if I can use a regulator from a CB350F to confirm the diagnosis?
The part nos are different, but maybe it’d work temporarily.

[grcamna2]

Insult to injury! My part has been returned to sender!!

Does anyone know if I can use a regulator from a CB350F to confirm the diagnosis?
The part nos are different, but maybe it’d work temporarily.

Oh No  !
I don't have an OEM regulator,but if I did I would certainly send it out to you right now:Today.
You're traveling across our country USA and I hate to see you held-up like this.

[bryanj]

The only difference is the connecorts point a different way due to not much space on 350.
750 point straight down from base 350 will point in accross the base but both work the same

[The Lone Builder]

Immediate panic over.
I chased it to the post office and it hadn’t been brought back in from the delivery run. SO they’re going to keep it for me and I can get it on Monday.

[grcamna2]

Immediate panic over.
I chased it to the post office and it hadn’t been brought back in from the delivery run. SO they’re going to keep it for me and I can get it on Monday.

 

[HondaMan]

Immediate panic over.
I chased it to the post office and it hadn’t been brought back in from the delivery run. SO they’re going to keep it for me and I can get it on Monday.

I'm also digging thru my old parts to see if I have a working 750 regulator, will update later tonight. I know I have some, but don't know their conditions.
Update: found one I refurbished in 2018. Sending PM to you if you need it.

[The Lone Builder]

So, just when I thought it was safe to go back in the water!

The regulator came and I fitted it. The bike ran with no issues for a week, then yesterday, it wouldn’t start with the starter, only with the kick start.

The battery was charged overnight and was reading over 13.4V when disconnected and 12,7 an hour later.

However first test: the bike wouldn't start with starter and when running the charging system was not increasing battery voltage at all! Not a squeak!!

I cleaned all the connectors and checked wiring from alternator wires through each connection block to the rectifier and all was good.

I then checked stator, field coil, and rectifier and all was well. When measuring the diodes on the rectifier, there is continuity only one way suggesting all is well, but on one of the yellows the resistance is 2,2Ω whilst on the other two it is 1,6Ω.

With a voltmeter hooked up to the yellow leads at the alternator, increasing the revs raised the voltage at all 3 combination to 45-50V AC, as per FSM. I repeated this at each connector block with the same result.

Then using an ammeter I checked current to the battery while monitoring battery voltage. From idle I was getting +/-8 Amps EDIT: WITH THE LIGHTS ON AND +/- 5A WITH THE LIGHTS OFF but the voltage was not changing.

One other thing is that the connector block from wiring loom to rectifier has evidence of overheating; the block has actually melted in places.

I replaced the new regulator with the one I removed and the result was the same.

So I’m stumped. Bad battery? Or is it the rectifier?  Or is it something else entirely?

[HondaMan]

I can send you a new plug & connectors, if you have some crimpers(?) I might have a set of those I could send, too, you'll have to send it back sometime.

The diode readings sound normal: in one place you are reading the resistance of 2 diodes in line with each other, and in the other it is just 1 doide, so those numbers make sense.

I think I have another good rectifier, will go look. While I go look, maybe you can slide one of those burnt-looking connectors out of the housing to see if it is distorted from heating? If one of them (particularly the Green (some are Black) or the Red one) is burnt and distorted, it will have lost its 'grip' on the mate in the other connector. This will break up the phase connection from that coil in the alternator, dropping the charge by 1/3 when it opens up from heat.
[Update]
I've got a good one, just needs the connector shell added. I have some. I can make it up and send it out if you want it: PM me your address?
Headed out to an appointment just now, will be back in an hour or so.

[The Lone Builder]

Thanks Mark,

I have already ordered new plugs, for both the 6-spade rectifier and the 8-spade one to the witring loom, although that looks good. I’ll “borrow” a crimper from AutoZone or somewhere, if I can’t find someone with one already.

I’ve tried again with a known good battery - AutoZone said Mine was good, while Advance Auto said it was bad! –  and the results were the same - on daylight, current 5A and voltage no change.

I got the red connector out and it looks OK. The green is another story; it won’t budge, and if it wasn’t distorted before, it sure is now. Im thinking to just cut the block and make direct connection.

[HondaMan]

Thanks Mark,

I have already ordered new plugs, for both the 6-spade rectifier and the 8-spade one to the witring loom, although that looks good. I’ll “borrow” a crimper from AutoZone or somewhere, if I can’t find someone with one already.

I’ve tried again with a known good battery - AutoZone said Mine was good, while Advance Auto said it was bad! –  and the results were the same - on daylight, current 5A and voltage no change.

I got the red connector out and it looks OK. The green is another story; it won’t budge, and if it wasn’t distorted before, it sure is now. Im thinking to just cut the block and make direct connection.

My concern here is that melted-looking plug: it indicates that too much current was going thru the connectors, which makes that heat. That means some sort of incident/accident/failure happened with whatever is on the other end of its wires, which it looks to be your rectifier? These silicon rectifiers can be damaged by connecting an already-live, too-much-amps-charger to the bike, even at the battery terminals, because the PIV (peak inverse voltage) rating of the OEM rectifiers was only 25 volts until the K5/F0 bikes. (Then it 'officially' went to 50 volts -many K3 bikes already had this rectifier, though). A 'regular' battery charger of 25 amps can have an open-circuit voltage of 62 volts, and some 10 amp chargers I've seen reach 26 volts when disconnected (mine is at 24.5 volts), so plugging in the charger and THEN connecting to these batteries will shock-load the rectifiers. After a number of these attacks the rectifiers can (and 2 of the 3 I just tested did) develop a 'leak', which is a partially-damaged PN silicon junction. The procedure needed with a charger of more than 5 amps is to connect to the battery FIRST, then turn on the charger, to prevent the open-circuit-voltage attack.

I suspect yours may have suffered this attack along the way somewhere, because then after they run a while, they get really hot from leaking and start shorting out, so to speak (technically, the PN junction goes into 'reverse avalanche' from the heating, and then it leaks -while hot - but looks 'normal' when cold). When cold the readings seem [close to] normal, but when running the current goes crazy high. Your previously-published voltages you've shown in this forum post suggest this is what may be happening with the rectifier, and it's melted housing suggests it even more.

Hence my opinions...

PM me your address if you'd like to have me send this one, after I put a connector on it.

[The Lone Builder]

That’s interesting about the battery chargers. I always, when I remember connect the battery first; I never knew why I did, it just seemed the right way to do it.

I was recently using two chargers, belonging to a lady biker who isn’t terribly technical, and I noticed that one of them had a 20A charging current, before I changed to the other one.

The rectifier is another with a circuit board replacement, done by the same German guy - who never got back to me incidentally – so again I guess it is difficult to say how it should behave. The rectifier, btw, had the resistor still in place, but it wasn’t connected to the circuit board; all three wires had been snipped.

I tore, literally, the connector block apart - the connectors were melted in place. The red and one of the yellow connectors broke during the process and another broke partially. I replaced them with available connectors and hooked them back up directly to the male (rectifier) side.

The results are:
 RPM.              Day                   Night
                 A          V           A            V
1000        2,5.       13          5          12,5   
2000        3,5        14          3,5       14,6
3000        4,0        14          5,2       13,6

Whilst the voltage seems OK, there still seems to be too much current flowing, momentarily the voltage will exceed 15V.
With the ignition off, there is no draw from battery, but when switched on the meter shows 5A, and with the headlight on this rises to 8A.

If you think it’s OK to ride with the above, I’ll head back to where the connectors are going and I’d be happy to have the other rectifier, if you could send it there. If not good to go now, I could wait where I am .

[rotortiller]

The electrical load on the bike with everything on is 8 or 9 amps at battery voltage and not running. A 15 volt transient will not hurt anything. When the bike is running the total electrical current may vary a bit since you have a voltage increase and an ignition coil drain decrease. The real difference now is the alternator is supplying the load.

edit-you may want to check the voltage above 4000 rpm and set the regulator there if need be.

[HondaMan]

If you think it’s OK to ride with the above, I’ll head back to where the connectors are going and I’d be happy to have the other rectifier, if you could send it there. If not good to go now, I could wait where I am .

Will send it Priority in the AM!
I got hung up with a dead JEEP today or would have done it this afternoon.

[PeWe]

I have seen several CB750 rectifiers were the green wire with connector has melted.
Many old one on eBay look like that.

This due to bad grounding to engine-frame according to other posts on this forum.
Melt when running the starter that need good ground.
No paint between ground connector- frame-engine to ensure good ground for starter, if not ground goes via rectifier

I have added an additional thick grey wire to rectifier  bolt where the green is attached. Direct from minus pole on battery.



I have bought an old rectifier that needed epoxy around the melted green connector in its housing plus electrical tape around the green as repair. Not the shown rectifier.

[The Lone Builder]

I’ll check grounding, but all green to earth  so far have registered 0Ω.

[Stev-o]

Just caught up on this thread and your issue.  Where are you holed up?   
I should have a spare regulator but sounds like HM has got you covered.

[The Lone Builder]

I’m on my way from Mt Orab, OH back to Greencastle, PA. Following PeWe’s comment, I’m only using kick start till I check out starter grounding.

[HondaMan]

I have added an additional thick grey wire to rectifier  bolt where the green is attached. Direct from minus pole on battery.



I have bought an old rectifier that needed epoxy around the melted green connector in its housing plus electrical tape around the green as repair. Not the shown rectifier.

That's going the extra mile!
I've also seen the Green rectifier wire melted on some of these bikes, and come to think of it, it was also after the owner(s) had "startup problems" and were probably spinning the starter a lot. On one in particular, the rectifier still worked OK, no charging issues either bike, though.
Chasing the melted wire cause on one of them, I suspected (and found) the ground wire connection to the engine case was poor: on that one the ground cable was not between the engine and frame and it also had a freshly painted engine and frame, corroded upper rear crossbolt, and crusty washers and nut. I ended up sanding the end of the engine's mount (loosened all the engine bolts, removed top rear, cleaned everything, used emery paper on sheet metal to get into engine mount (painted) and frame mount (painted) faces, then put it all back together with a drop of oil. Worked fine after that.

[PeWe]

The additional ground wire on the  rectifier is your idea, Mark. From a post you wrote, maybe your thoughts ....

I had a roll of both grey 2.5mm2 and 4.0mm2 wire since the 80's...

Extra insurance