What fresh hell is this? (Battery?)

12V across the battery terminals. Good spark. It starts and runs well. Headlight on and still no problem. But after 5-10 minutes; nothing. No power to anything anywhere and the thing stops.

The headlight gets brighter on increased RPM so the alternator seems to be working but for some reason, it doesn't seem to be drawing off the battery while running.

Could this be a faulty rectifier? A short somewhere? Time for a new battery?

Any other suggestions would be appreciated.

Thanks

BC

Check your battery with a load on it. It should hold the headlamp at 12 volts for a minute or so. Otherwise check voltage vs. rpm. You need to see 14V or so during charging. I suppose it could be your regulator.

This sort of happened to me last week, my JD2020 started right up, turned it off and it wouldn't start. 12.4V on the battery, but as soon as I put the switch in the acc position, the voltage dropped to 5V. Bad battery.

Dave
69S

Stillreel said:

12V across the battery terminals. Good spark. It starts and runs well. Headlight on and still no problem. But after 5-10 minutes; nothing. No power to anything anywhere and the thing stops.

The headlight gets brighter on increased RPM so the alternator seems to be working but for some reason, it doesn't seem to be drawing off the battery while running.

Could this be a faulty rectifier? A short somewhere? Time for a new battery?

Any other suggestions would be appreciated.

Thanks

BC

Click to expand...

Mine did something similar and it required a charge to get it going again. One of the diodes in the original rectifier vibrated and broke off.
First thing to check is to see if increased revs gives you more voltage across the battery. Based on the headlight, I assume you are. You should get some voltage numbers.
You can also take the battery down to most of the chain auto stores and have them test to see if that is the problem.

After it runs for 5-10 minutes, can you start and run again or do you need to charge the battery?
Do you have the original rectifier and zener or an aftermarket solid state device?

Had this a happen with a bad but good appearing fuse, more than once by glass and plastic type fuses. Also suspect terminals wires no where near the charger or battery shorting out with vibration motion till sucking life out the ignition and lights. I had to pop primary when I couldn't fine nothing wrong a few days ago to solve no lights or fire issue with just one nut loose on stator. A Cdo can have more than one issue at once each doing the same thing too. Found show stoppers in tail light and head light. Turn key on and meter battery to see if voltage plunge after a bit, if not then lights on and see till some sense of what to do or try next.

I have a similar problem right now with the Commando.on my bike, the spring loaded connections at the fuse holder are the problem. If I wiggle the fuse holder and wires with key on and engine off, lights go from bright to dim to right off and back to bright again.

Glen

I had your exact same problem a couple months ago.

The battery "seemed" to be just fine using the voltmeter, volts went up when rrpms increased to show that yes it supposedly was charging the battery.

The problem was fixed easily with a, wait for it,.....new battery!

The suggestion up thread to do a load test on the battery is right on, and you can do a quick one simply by turning the headlight on in the garage without starting the motor and leave it and the tail light on for about three minutes, then put a volt meter on the battery and if you are not reading 12.5 volts you need a new battery, regardless of whether it charges or not.

I had similar problem.
Battery about four years old.
Took it to auto parts store and they checked it out and seemed ok.
Charged it for me and in about two days same problem, wouldn't even drive my flashers.
Replaced with new Shohei Lithium Iron battery from OldBritts now happy for last three months.

I suggest is battery more than two years old it is the most suspect.

Had the same problem earlier this year on my VFR. Voltmeter checked out OK after a charge but it wouldn't start. Somebody told me it was taking a 'surface charge'. Like having a 0.01ah battery. Around 4 years old, kaput.

But he should check out all the connections between the battery and the charging circuit, plus anything with electrical connection that can get corroded. It's not always as simple as just replacing the battery, sometimes. I was spoiled by having a Miata Panasonic AGM battery that lasted 11 years. You get used to it and expect the same, but my JD2020 800CCA dual batteries lasted only 4 years, just past the warranty. You can imagine what it's like to start a diesel tractor when the snow is about 2' high. I've got some Yausa 3 stage managers coming to see if I can extend that because the batteries are getting to be $100 each now. Come to think of it, I gave about $80 for an 8AH AGM from Clubman, but it seems fine 2 years on.

Dave
69S

Problem sorted. I think. I hope. But first, a confession; it's actually the '68 Triumph that had (has) the problem. I find that the Norton user group is a bit more informed than my Triumph colleagues. That is not to say OCD.

Anyway, the Triumph has single source power from the battery to the amp meter then onto the ignition switch. From there its wired through to the coils etc. However, the wiring takes a brief detour to the (f'g) horn and there lies the severed connection. One side of the spade connection had worked free, allowing only an intermittent charge through to the amp meter et al.

So I've repaired it now, while at work and will test this theory on the ride home.

Thanks again for the input. I've realized that its probably time for a new battery anyway.

BC

You evil sod tricking us like that! I feel so abused, you do realize you risk angering the Lucas Gods of eternil darkness by such trickery...

The Dark Lord has been contained. But I won't tempt fate again.

Oh yeee of little fear, thou hath no idea how long a memory the Gods can have!!!