I need a new battery

[notme]

Yo Bender,

do you have any diagrams/service info either pre or post mod or can you find such for your model?

I believe the original system was an AC lighting type, i.e. a coil off the alternator just for lighting, battery only used for ignition.

Has it been upgraded to a "normal" motorcycle system - i.e. standard regulator rectifier and all lights powered off 12VDC?

If your charging system is working correctly, your battery should not run down, as the charging system will provide all power necessary to run the bike including headlights as well as charging the battery. You say that you have 15V at the battery - what rpm? You should have about that voltage at about 3000rpm - if you do, then the charging system is probably OK (see here for a comprehensive test chart)

However, you are saying the battery does run down......by the way - what do you do when it is flat? Put it on an external charger? I'm wondering if the charging system is in fact buggered, and the battery is just slowly running down all the time, but it dies quicker when you have the headlight on of course.

The point is, battery capacity should not be an issue, any standard IC engine battery is known as an SLI battery (Starting, Lighting, Ignition) and only exists to provide stored energy to turn the engine over. The capacity of the battery has very little bearing on the engine once it is running. If your charging system is working properly, it is always producing an excess of energy, which is converted to heat by the regulator/rectifier unit.

You have a multimeter, so can you run thorugh the chart linked above? note - try it with and without the headlight on.....

[Bender]

Allun, many thanks for the help, which I've run through. The link to the motorcycle charging system fault finding flow chart doesn't work, but I used google to find this one (link) which I think is comprehensive.

Step 1: connect mm to battery and rev to 2500 rpm, voltage is 13.43. Rev the engine to 5000 rpm, volts go to 15.12.

It has four wires from the RR.

If I connect to the red/white wire with the connector box undone I get .3 to .5, fluctuating all the time. If I leave the connector box done up and connect to the R/W wire on either side I get 12.8 volts. Not sure what that means.

Do you agree that it could be a bad connection as the flow chart suggests?. I'd like a second opinion on this because it means stripping the wiring loom back - it is extremely well insulated and it seems there are connections underneath.

The connections inside the connector box looked average so I CRCed it and put that trendy connection stuff on it (bloody name I can't remember now but we used to use it on all the connectors on our enduro bikes back in't day.

I pulled the RR apart. There are a couple of things I want to check. First, the bracket that connects it to the frame is connected to powder coat. Does this have to be well earthed, because it isn't. Second, the RR is a black box (pix below) mounted onto copper heat sinks.

It has the number BR356 an an earth symbol a 97 moulded into it. Don't know if or what that means.

Whaddayareckon?

[notme]

Allun, many thanks for the help, which I've run through. The link to the motorcycle charging system fault finding flow chart doesn't work, but I used google to find this one (link) which I think is comprehensive.

hmm...link works for me, hopefully for others or i'll have to repost it....the one you have linked to is the same one anyway.

Well, this is where it gets interesting - your photos show a standard low frequency bridge rectifier! This is not a motorcycle regulator rectifier, it is just a standard low power general purpose electronic part.

So, your bike has been modded to 12V not by changing it to a standard motorcycle RR system, but by changing it to a custom system.

That means that the fault finding chart and anything else that would normally apply to troubleshooting a charging system doesn't apply!

I would imagine that the person that changed it put a stator out of a slightly different Honda into your alternator (with different windings to get a higher output), changed the rectifier, and put a 12V ignition coil in. That's about all I reckon you'd need to do to change a bike like yours from 6v to 12v - oh and 12v bulbs all round of course.

So, now your tale of woe regarding the headlight flattening the battery makes a lot more sense :-).

Big question - did the bike ever run fine i.e. no battery problems? If YES, then it has developed a fault and we can follow that path. If NO, then it was not modified properly in the first place, and we need to resolve that.

A couple of questions and answers:

........the bracket that connects it to the frame is connected to powder coat. Does this have to be well earthed, because it isn't.

No it doesn't. The case of the rectifier bridge is not connected to anything inside, so it can be earthed or not with no change. One reason to connect it to the frame without powder coat in between is heat transfer though - it will sink heat into the frame better without powder coat in the way. We can deal with this later after we solve the original problem - which may in fact be caused by poor heat dissipation anyway!

It has the number BR356 an an earth symbol a 97 moulded into it. Don't know if or what that means.

It's the part number - like most electronic components the numbers indicate the part ratings. This is a bridge rectifier (BR356) rated at 35 Amps (BR356) at 600V (BR356).

We can test this part easily enough - and the fix might be simply that this part has overheated and died, which would be excellent news for you.

To test it, we need to disconnect it from the bike - hopefully there are connectors that will help you here, otherwise you're going to have to desolder the wires or cut them. Take a photo before you cut or desolder any wires, and write which wire went where with vivid on the rectifier (after cleaning it up with meths).

Once the rectifier is off the bike, get your multimeter, and put it on diode test mode. The symbol for this mode will look similar to this:




Check that when you touch the multimeter probes together the meter reads 0.00 on the display, and it will likely beep as well. Check that when the probes are apart the meter reads "OL" or maybe "--".

Touch one of the probes to the metal case of the rectifier - doesn't matter which one, and touch the other probe to each of the 4 terminal legs one by one. None should beep or read anything on the display apart from "OL".

Then test between the following points, and tell me what you get for each. You should get around 0.3 to 1.0 and a short beep that stops by itself even if you keep the probes connected to the rectifier, but definitely NOT "OL" or "0.00" and a continuous beep.

1. Put the black meter probe on the rectifier pin that had the yellow wire, and the red probe on the rectifier pin that had the red/white wire. What does the meter say?

2. Put the black meter probe on the rectifier pin that had the pink wire, and the red probe on the rectifier pin that had the red/white wire. What does the meter say?

3. Put the black meter probe on the rectifier pin that had the green wire, and the red probes on the rectifier pin that had the pink wire. What does the meter say?

4. Put the black meter probe on the rectifier pin that had the green wire, and the red probes on the rectifier pin that had the yellow wire. What does the meter say?

5. Now put the meter on resistance mode (ohms) and probe between the yellow and pink wires on the bike i.e. going back to the alternator stator. What's the reading in ohms?

I recommend a box of beer and a nice day in the sun to do all this, but that's just me :-)

[Bender]

Check that when you touch the multimeter probes together the meter reads 0.00 on the display, and it will likely beep as well. Check that when the probes are apart the meter reads "OL" or maybe "--".

My multimeter comes up with a 1 when I switch it to diode test mode, which I assume is the symbol it uses for that mode.

When I touch the leads together it goes to 0.00.

1. Put the black meter probe on the rectifier pin that had the yellow wire, and the red probe on the rectifier pin that had the red/white wire. What does the meter say?

1 (i.e. no change)

2. Put the black meter probe on the rectifier pin that had the pink wire, and the red probe on the rectifier pin that had the red/white wire. What does the meter say?

1 (no change)

3. Put the black meter probe on the rectifier pin that had the green wire, and the red probes on the rectifier pin that had the pink wire. What does the meter say?

1 (no change)

4. Put the black meter probe on the rectifier pin that had the green wire, and the red probes on the rectifier pin that had the yellow wire. What does the meter say?

1 (no change)

5. Now put the meter on resistance mode (ohms) and probe between the yellow and pink wires on the bike i.e. going back to the alternator stator. What's the reading in ohms?

Pink / yellow 1.7



Just a note, the wires coming from the stator are not standard colours. There is a blue wire, brown wire and three green wires.

I chose the wires that corresponded to pink and yellow on the connector box.

In answer to your question about whether the bike had a problem in the past, it is difficult to know. It sat in forum member Voltaire's garage for many years and had originally been ridden by his wife.

The rebuild of the bike was undertaken by a person who was something of a perfectionist. He did not rebuild the bike to factory standard but made a number of sensible modifications such as decent brakes, alloy rims and the 12V electrics.

The rebuild was done to a very high standard so I think that any problems are likely to have developed post-rebuild rather than during the rebuild. He also rode the bike for several years after the rebuild and I'm sure that if there had been a problem, he would have noticed and fixed it. I think (but of course nothing is ever certain).

[notme]

Can you try another set of readings, multimeter on diode test mode:

1. black probe to terminal that had the yellow wire, red probe to the one that had the green wire

2. black probe to terminal that had the red/white wire, red probe to the one that had the yellow wire

3.black probe to terminal that had the pink wire, red to the one that had the green wire

4. black probe to terminal that had the red/white wire, red to the one that had the pink wire

Hopefully these all read somewhere between 0.3 and 1.0, and they should all be the same (within a small tolerance).

Did you test that none of the terminals read anything between each of them and the metal case of the rectifier?

[Bender]

Here we go... I wasn't sure whether you meant the bridge rectifier or the wires from the stator so I did both.

1. black probe to terminal that had the yellow wire, red probe to the one that had the green wire

BR: 540
Stator: no change

2. black probe to terminal that had the red/white wire, red probe to the one that had the yellow wire

BR: 1195
Stator: 003 (note there is no red/white wire on that connector, so I used the white.

3.black probe to terminal that had the pink wire, red to the one that had the green wire

BR: 530
Stator: no change

4. black probe to terminal that had the red/white wire, red to the one that had the pink wire

BR: 515
Stator: 001

Did you test that none of the terminals read anything between each of them and the metal case of the rectifier?

Yes, no change in reading.

[notme]

BR: 1195

This one is a concern.

Does your multimeter have a current setting of at least 10 Amps?

[Bender]

Yes it does.

[notme]

Measure the battery current to see what's going on there. You'll need to plug your red meter probe into a different socket on the meter to measure current instead of voltage - please remember not to measure anything apart from current while you have the meter in this state or you will cause sparks!

So:

1. Plug the rectifier and everything back in as it was so the bike is back to running order. Leave the battery negative lead off.

2. Set up meter for current. You have to change the red probe to a different socket labeled DCA or CURRENT or 10A max, and set the dial to DC CURRENT or AMPS DC or DCA or similar.

3. Connect the black meter probe to the battery negative terminal, and the red meter probe to the battery negative cable. Make these connections good, maybe tape the connections securely or clamp the meter probe in the battery terminal or similar. Make sure they don't short out to other parts of the bike - remember the bike will vibrate with the engine running and they might move so maybe tape them to some part of the frame.

4. Start the bike, turn off as much electrical load as you can (mainly headlight) and observe the meter reading at idle. If the current reading is positive, the battery is charging, if the current is negative, it is discharging. Try varying the revs, turning the headlight on etc and note down some currents. Be careful note to do anything that makes the meter read more than about 5Amps for more than a minute or so, as the wires on your meter probes will start getting warm above that. If you do anything that reads more than 10A your meter fuse will blow.

When done, put the red meter probe back into the voltage measuring socket so you don't accidentally try and put the meter across your battery and blow the fuse!

[Bender]

I did that. Set up multimeter, black probe to battery negative, red lead to battery negative cable.

With the key switched on but the engine not running, the reading was 0.19.

Idle .61
Headlight on at idle 2.35 to 2.68
5000 rpm -1.25
5000 rpm headlight on .35
Idle headlight and blinker on 2.4 tp 3.3
Idle headlight, blinker, brake light on 3.5 4.2


5000rpm headlight, blinker, horn going .35 to .57

I hope you can see something in there because I can't.

[notme]

Well, now we know what's happening - the WHY is still not clear though.

First off - I made a mistake, with the meter connected the way I told you to, positive current direction means the battery is discharging, negative means charging. Sorry! It doesn't change the results but I thought I'd clarify so that you understand what I am saying below...

Ignition on, engine off 0.19A
Idle .61A
Headlight on at idle 2.35 to 2.68A
5000 rpm -1.25A
5000 rpm headlight on .35A
Idle headlight and blinker on 2.4A to 3.3A
Idle headlight, blinker, brake light on 3.5A to 4.2A
5000rpm headlight, blinker, horn going .35A to .57A

Basically if you look at the results, you can see that the only time the battery is charging is when you have revs and the headlight off.

In all the other tests, your battery is being discharged, just to different degrees. The worst is obviously when the headlight, blinker, and brake light are all on, and the bike is idling (no charge from the alternator).

When you have all these things on, and you give it revs, the alternator is providing almost all the current needed to run those things, except for the last 0.35 to 0.57A which must be provided by the battery. If you just revved a little bit more you might find that the number drops to 0 - when it drops to zero, the alternator is powering all the bike's loads, and the battery is not having to provide the top up. If you rev more, you should find that the number becomes negative, which means the alternator is providing more than the headlight etc need, and so the leftovers will go into charging the battery.

So, now we know that the problem is that the bike is not charging the battery. Which BTW is basically what you said in the beginning .

The question is - WHY.... well, I can only conclude that the alternator needs upgrading, it is just not providing enough juice. You could leave the alternator as is, and go back to the stock headlight, or keep the more power hungry headlight and upgrade the alternator. If you did that however, you would need a modern regulator rectifier unit, or you'd kill the battery fairly quickly. A modern bike has a shiteload more charging power avaialble (about 400W) so really the only "problem" here is that you are asking too much of the old girl.

Do you have contact with the previous owner to ask if this all sounds familiar? You might just get an answer like "oh yeah I would put it on a charger every couple of weeks" ....

BTW, well f$#kin done on being patient and going through this - I'm always happy to help but a lot of people would have given up by now :-) Hopefully you have learned a bit more about how your bike works, more importantly you haven't paid someone else to do what you'll have to admit was really a piss easy few tasks!

[Bender]

Thank you Allun for taking me through that. I also learned how to do one more thing on the multi meter.

Regards upgrading the alternator, I'd like some advice on how to go about that. Do I get the existing one re-wound, or is it going to be possible to get a better Honda one that will bolt straight in? Do I phone the dudes at Econohonda and suss out what might fit? It would be logical for Honda to use the same set up for a range of its smaller bikes, just changing the number of windings and coils. Wouldn't it?

Can I add some more windings to the charging coil of the existing set up. Do I need a new and better rotor?

I can understand throwing it on the charger from time to time and I may well end up doing that depending on the complexity and cost of the fix.

If I wasn't required by some dumb-arse law to keep the headlight on, it wouldn't be a problem. It's not a bike you spend a lot of time on at night.

I could change the headlight to the standard one that draws only 35 watts - would that be enough to solve the problem or would I also still need more jooce?

[notme]

Hey dude,


you are dead right on changing the stator - further evidence that you have actually been paying attention and following along :-)

Exactly as you say, you can stick another Honda stator into your bike and voila - more alternator output (search google - i am not expert on your bike but there seems to be lotsa info out there).

BUT.....yup, there's the but. It seems like at this stage you understand basically what's happening, i.e. that your alternator is not putting out enough grunt to charge your battery as well as light your headlight and indicators, brake lights etc.

So, you can see that increasing the alternator output fixes this - BUT the only thing limiting your battery charging current at the moment is your weak alternator.

If you had an alternator with more go, you could run a more powerful headlight, but would overcharge your battery. To stop this happening you could get a motorcycle regulator/rectifier which is a bit different to your simple rectifier bridge....and means a lot of wiring changes.

SO, maybe the person that converted your bike to 12V was actually quite on to it and decide to keep it simple.....at the expense of not being able to upgrade the weak stock headlight :-(

If you changed to the stock 35W headlight you miiiiight still have a problem, hard to say but you might just try it for a few weeks. You said that at idle with headlight off the battery is discharging by 0.61A, but when you rev (as you do normally while riding) it will charge...you might end up being OK, or having to only chuck it on the charger once every few months depending on how often you ride.

Another fix might be to fit a daytime running lamp that meets all the legal requirements but does not draw sp much power, for example a LED light. Are you even sure that the headlight must be on during the day for a 1970's bike? I'm not saying it's not a good idea, but it might be optional for a bike of your one's age.

Anyway - there are still things that can be done, but I think we have proven that you don't have much to worry about as far as faults go, there's nothing wrong with your bike as such, it's just not working the way it ideally would.

I'm happy to help with converting it to a "normal" motorcycle rectifier/regulator system if you want, but be prepared to get intimate with your wiring :-)

A

[Bender]

Allun,

This morning I've wired in a 12V 35W incandescent headlight bulb and I'm getting good charge (.2 - 1.5A) pretty much from idle (I reversed the MM leads so I got proper + and - readings.)

So the way ahead is clear - revert to a crappy old headlight and obey the law.


I'll do a scout around today and see if there is any such thing as an H4 35W quartz-halogen bulb but I was told by the guys at the local Repco that such an animal didn't exist.

[notme]

Cool - I'm glad we've established that there's no real fault as such, because it means yer bike ain't broken! It just uses a headlight as a charge regulator..... :-)

With the 35W headlight on permanently, the battery should get just enough current to charge well, without overcharging, so it looks like the best option.