Topic: 1974 Honda CB550 Charging problem Killing battery.

[kaptainkid1]

Hi all,

I've got a 74 CB550 that isn't holding a charge, keeps dying after 25 miles or so of riding around town.

I've replaced the battery, then ran some preliminary tests with lights on.
                                  Lights on:            Lights off:
•   Battery terminal check- 12.5 v            12.5v
•   At idle-11.8 v                                    12.1v
•   At 2000- 12.30v                                12.5v
•   At 3000- 12.5v                                  13.1v
•   At 4000- 12.9v                                  14.0v
•   At 5,000-13.1 v                                 14.4v

At idle, I should be at 12v, correct?
and at 5.5k I should be above 14?

These figures seem pretty close to stock, so why am I still getting problems? Damn thing died after 25 miles again. I can tell it's the battery dying because my turn signals start to go out and stop blinking right as the battery is on its dying breaths. Is there anyway to know what I should test from here to get a good diagnosis? If the reg/rec or stator were faulty, wouldn't I just be stuck at 12v.s?

I've been trying to check/clean terminal connections, but they all seem to be in good shape so far. Still no change.
I've also pulled the 74' CB550 Rectifier and Regulator and put them on my CB750 bike which doesn't have any charging problem and it's charging fine. I also swap the good cb750 reg/rect to the cb550 and it's showing the low charging issue. I know the problem is still somewhere on the CB550. So i dont think the reg/rect are the problem.

I'm going to check the ohms on the stator tomorrow and wanted to know if anyone can give leads on fixing this problem. 

[RJ CB450]

Also check your charging at lower RPMs.  It is important to figure out where your charging begins which should be at a much lower RPM and reaching the 14ish volts well before that 5500.  Reg/rec faulty can have one of two issues.  First is if it itself is what failed, often it can result in just discharging to ground for no charging.  But if say the ground isn't correct, you can overcharge and cook your battery and the rectifier as well.  Since you are not over charging and doesn't sound like a fried battery, am betting the rectifier is fine.  The fact it holds at 14v means it is probably working fine.

Usually I find it is the field coil that has failed in personal and associates experience.  Can do a quick ohm check.  I do not know the 550, but generally it is often 3-6 ohms of resistance depending on bike for ideal.  If less than that, it is a short and more a bad wire.  I would do an ohms check on that first and then see if that stands out.

[scottly]

Do a voltage drop test first: place one meter probe on the battery + terminal, and the other meter probe on the regulator black terminal. With the key on, note the voltage. (The engine doesn't have to be running, but you may want to measure both with and without the lights on.) The reading should be less than 1 volt.

[scottly]

Usually I find it is the field coil that has failed in personal and associates experience.  Can do a quick ohm check.  I do not know the 550, but generally it is often 3-6 ohms of resistance depending on bike for ideal.

The field coils and stators on these bikes are usually not prone to failure, RJ.

[RJ CB450]

The field coils and stators on these bikes are usually not prone to failure, RJ.

Yeah, I was pondering that versus the brushed designs that I have the experience with.  Still an easy test worth checking.  The symptoms read like weak charging and that usually is the coil or stator.  Far easier to test both those before hitting the rectifier.  But that said, if this is a recent purchase and put a new battery in, the rectifier could have been toasted before sale.  If rectifier isn't working right, doubt would ever see that 14v, or it would overcharge and cook batteries plus itself... then never charge.

[scottly]

Yeah, for some reason Honda couldn't make a decent brushed rotor system, even though the design had been proven reliable in autos for over a decade. The early 1979 CBX was known to wear out the outer brush in about 8000 miles; it happened to two friends on the same day, while we were on a trip to CO, outside of Winnemucca NV.   

[dave500]

first thing is to disconnect all the connectors on the entire bike and clean them well,before you start chasing your tail.

[flatlander]

yes definitely clean all connectors then check at what rpm the battery starts charging. it should be after 2500rpm or so.
here's a post from twotired that can be helpful in case you have to chase down problems: http://forums.sohc4.net/index.php/topic,134836.msg1515431.html#msg1515431

[TwoTired]

Do a voltage drop test first: place one meter probe on the battery + terminal, and the other meter probe on the regulator black terminal. With the key on, note the voltage. (The engine doesn't have to be running, but you may want to measure both with and without the lights on.) The reading should be less than 1 volt.

^^^This...

I would also check the battery neg to vreg Green connection in the same way.  The sum of these two measurements is the error reported to the vreg of the actual battery voltage.  Vreg can't do its job if it doesn't know the actual battery voltage.

Cheers,

[kaptainkid1]

I just clean all the connectors from the stator, Regulator, Rectifier and battery terminals. All points connecting to the frame and engine contacts. I even went the extra step and ran another ground wire directly to engine just incase the ground wire to the frame was not connecting properly.

I've ran another test and it seems it's the same number low charging and doesn't really start to charge the battery with light on until 4500-6000 rpm and that's at: 13.4-13.8volts.
So I checked the Stator wire and I'm 1.6 ohms with all three yellow wires. The Green & white wire I"m getting from the stator is 4.3 ohms.

I'm really getting stumped here and new directions would help. I have a back up stator and but it seems I'm getting the same figures from both the stator on the bike as I do the back up.

What should I do next?

 

[kaptainkid1]

I saw this post about the Regulator:( really don't understand what this post mean? Do I adjust the gaps to increase the charging points and lower rpms with the Regulator? someone please explain...) 

This 750 Vreg illustration is so you know where to measure gaps (verify gap spec w your 550 manual), and clean the point gap w brake cleaner as you would ignition points.
If you do have to adjust, do them in this order, as the reverse negatively effects the point gap once the core gap is adjusted.

[scottly]

What should I do next?

What I told you to do first.

[Bankerdanny]

It is wise to come here for help. It is foolish to ignore the help when it is provided.

[kaptainkid1]

Do a voltage drop test first: place one meter probe on the battery + terminal, and the other meter probe on the regulator black terminal. With the key on, note the voltage. (The engine doesn't have to be running, but you may want to measure both with and without the lights on.) The reading should be less than 1 volt.

Ill do this tomorrow and get results posted next

[kaptainkid1]

Do a voltage drop test first: place one meter probe on the battery + terminal, and the other meter probe on the regulator black terminal. With the key on, note the voltage. (The engine doesn't have to be running, but you may want to measure both with and without the lights on.) The reading should be less than 1 volt.

I'm not sure what this test mean but here is the following data:
Not Running:
Lights on: 1.68 v
Lights off: 1.07v

Running :
Lights on: 1.53v
lights off: 1.03v

[TwoTired]

What it means is that the vreg doesn't know what voltage the battery truly has, and you have a connection problem or switch degradation issue to resolve.

You may also have a voltage loss in the negative connection pathway, as well.  That's why I asked you to do a v drop test on the neg to green pathway.  The loses are cumulative for both the path you measured and the path you didn't.


Cheers,

[kaptainkid1]

What it means is that the vreg doesn't know what voltage the battery truly has, and you have a connection problem or switch degradation issue to resolve.

You may also have a voltage loss in the negative connection pathway, as well.  That's why I asked you to do a v drop test on the neg to green pathway.  The loses are cumulative for both the path you measured and the path you didn't.


Cheers,

Let me start off by saying I'm totally new to wiring and didn't really understand vreg term and I'm guessing after doing the voltage drop down test it means vreg(voltage regualor). So bare with me as I'm making mistakes and figuring out the short terms.

VReg Test: Negative terminal and Voltage Regulator

Turn on and not Running:
Lights:
On: 0.25v
Off: 0.13v

Running:
Lights:
On: 0.13v
Off: 0.01v

I'm even not sure if I'm doing the test right and hopefully these number are correct.

[TwoTired]

Your negative route numbers are a bit confusing.  Does show there is resistance in the pathway.  But running vibration seems to improve it indicating something isn't firmly connected. ...or your test lead probe tips are dirty.

Probably best to focus on the Positive pathway losses first.  As that clearly shows the most loss.  I'd guess old worn switch contacts, if you've done the connector cleaning properly.

Cheers,

[kaptainkid1]

Your negative route numbers are a bit confusing.  Does show there is resistance in the pathway.  But running vibration seems to improve it indicating something isn't firmly connected. ...or your test lead probe tips are dirty.

Probably best to focus on the Positive pathway losses first.  As that clearly shows the most loss.  I'd guess old worn switch contacts, if you've done the connector cleaning properly.

Cheers,

Well I might have done the Negative drop down test incorrectly. I noticed my volt meter is a crappy Harbor feights tool.
So anyways I decided to put on a new starter switch which I had as a back up and the numbers are the same as before low charging system. I worked on the positive leads and clean those connections up and I'm still getting the same low voltage charging on my system. I'm going to pick up a new volt meter and double check all the ohms and charges again.

[TwoTired]

Check the Vdrop across the key switch?  They have contacts inside that can degrade.  Fuse clips are also inline of the power path.
I don't think the starter button has anything to do with power getting to the Vreg sense terminal.

Putting the voltmeter leads across any in line device in the power path will report the voltage lost in that specific device.

Cheers,

[scottly]

Fuse clips are also inline of the power path.

^^^
Check that the fuse clips are clean. It's a common problem. The 15 amp main fuse is the link between the battery and the ignition switch, and the reg is fed from the ignition switch. The starter switch has nothing to do with the regulator.
I think you owe Danny an apology. You ignored both my first post as well as TwoTired's confirmation. If Lloyd and I agree on something, it's probably true.

[kaptainkid1]

Let me clairify I didn't just change the starter switch but connected a whole new right side switches which includes a clean second set of run/off switch which I thought could contribute to the low voltage. Since I rule out right side switches and cleaned the ignition key. I figure I've cleaned by using steel brush on all the connections from the battery to rect/reg, all the connections on the side panel, all the wires in the head lamp and even the fuse holder. I'm still stumped and I think the last thing I'll need to change is the stator. I'm getting 1.6 ohm on the three yellow wires coming out of the stator and according to the manual it should be 3.5 ohm. So I have three stators, one on my cb750 which charges fine which shows an 1.6 ohm and second set which I'm not sure if it's working properly but is getting 1.6 ohms too. So I'm guessing my volt meter isn't working correctly or the manual isn't correct. I got a new volt meter today and retest these components. 

[TwoTired]

Very unlikely to be a stator problem.  Book says the stator should measure 0.35 ohms between yellows.  Common meters usually have that and more resistance just in their meter leads.  So, that must be subtracted out of the actual measurement.   There must be no continuity from the yellows to engine case.

The bar controls are not included in the power flow path from battery to V reg.  The fuse block and keyswitch are.  Cleaning the key does nothing for the internal contacts of the key switch.

Also, there are connectors  mid path between components.  So, if you are only cleaning the source and end points, you have more cleaning to do.  Check the wire diagram in the Honda shop manual.  It depicts the connectors and all the devices in the path between battery and V reg that you need to address.

Cheers,

[Deltarider]

Hi all, I've got a 74 CB550 that isn't holding a charge, keeps dying after 25 miles or so of riding around town.

Hi. Since when do you have this bike and since when do you have this problem? What is the last thing you did before the problem occured?
Without having read all the above: have you checked if the wires isolation coming from the generator is not chafed where they exit the left crankcase cover?
Any wiring that is not standard like to accessories?

[kaptainkid1]

Hi all, I've got a 74 CB550 that isn't holding a charge, keeps dying after 25 miles or so of riding around town.

Hi. Since when do you have this bike and since when do you have this problem? What is the last thing you did before the problem occured?
Without having read all the above: have you checked if the wires isolation coming from the generator is not chafed where they exit the left crankcase cover?
Any wiring that is not standard like to accessories?

This was a barn find bike so I don't know the condition before I bought it. It sat for 25 years and I replaced alot of parts to get her running. So the final problem is the low charge issue. The bike was unmolested. No wire cuts or mods on the bike. The wires all look good for sitting outside in garage for 25 years. I've looked over all the wires on the entire bike, from the headlight bucket connections to clean and wire brushing all the connections from the stator to the battery and everything in between. Still getting a low charge.

Here is link with the bike started with the Vmeter attached with lights on:
https://photos.app.goo.gl/Rsb4ziN2iLnXXmIy1

Lights off:
https://photos.app.goo.gl/NYU1kYTcCCF7rk9f7