Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board Total electric fail.

Been chasing ghosts for two days on the 68. If it's electric it does not work. Bat shows 12.9V. By bypassing the ignition I got 12.8 to the headlight and the Pazon. Nothing works. Sweat, swear,sweat, swear. Wired the Pazon to the bat. Nothing. Finally wired a headlight bulb straight to the bat. Nothing. Took the same bulb over to the 72. Hooked it up and it worked fine. How can a battery show 12.9V and not be able to turn on a light?

The +ve ground battery connection to the harness?

The battery is not hooked up to anything.Light bulb went directly to the posts.
With the bypass I got 12V to the horn. Horn button checks out OK. No horn????

If it ever cools down I'll pull the battery out of the 72 and see what happens.

what does the circuit voltage drop to under load ?

I can't put a load on it because it will not do any work. The only thing it will work on is the multi-meter. I did get the red "ignition on" light to come on with the bypass but it did not last very long.

I don't believe it, if the battery has anything in it, which at 12.6+V it must have, it must at least make the filament glow, surely?
Try again I suggest.

Or is the battery so shagged that you're just having a laugh with us?

The VERY first thing I ever do when trouble-shooting an electrical problem is to load-test the battery with a load-tester.

Hook it up, throw the switch, and see what happens. If the battery shows voltage, but won't supply any current, then it's toast. Happens to batteries all the time.

If you hook up a light bulb straight across the battery terminals, and it won't light up, just toss the battery and put in a new one. There are a hundred internal battery fail modes; don't waste time trying to figure out which one got you this time .... !

Lannis

I rarely laugh at electrical problems when it's 100 degrees in the garage. I'll swap out the battery tomorrow. Film at eleven.

Hi Desco, Are you saying volt meter shows 12.9v, but in fact the battery won't light the head bulb. Yet your other bike's battery lights bulb?

Is that what you are saying?

Not a common failure, but we'd see this at work on occasion. I had it happen to me one day on my car. Went to store, was working good. Came out 10 minutes later, nothing! Yet at shop showed 12+ volts. Load test showed zero. battery was only few months old. Covered by warranty.

This is usually caused by a fractured connector between cells or at terminal connection inside the battery. The connector is holding on by only a thread. Ski Voltage shows good because volt meter takes tiny current to read. But when you use a load it cannot pass the current.

I expect if you measured voltage with bulb hooked up, it would be near zero.

This can come on instantly as the connector fractures. Temperature can push the broken parts together making a temporary repair.

I expect when you swap batteries problem will be cured. Put bad battery in 2nd bike & see what it does as a proof.
Don

I had a battery fail in that way, voltage checked out but would not supply any amps, it had a high internal resistance. Just stopped working on the way home, clue was the LED voltage indicator showing good voltage but dim lights. Took fuse out and went home on capacitor, which is why I now always fit one and a battery.

TR
Are you saying volt meter shows 12.9v, but in fact the battery won't light the head bulb. Yet your other bike's battery lights bulb?
Yes.
It's been maddening to find voltage all over the bike but nothing works,

What cap do you use Kommando?

One off ebay, the White one is on the Victor.




With a decompressor on a B44 you have the option to pre-prime the capacitor when its oversized,




You can see from the wiring diagram the capacitor is live even with the ignition off, so you can kick the bike over a few times with the decompressor pulled, tickle the carb, set the kickstart just over TDC. Then quickly turn on the ignition and kick, this ensures a high voltage for the Boyer. You can see this with the voltage LED, do some priming kicks and then turn the ignition on and it takes a few seconds for the voltage to decay.

It WAS the battery. Two days of farting around. Always do the easy tests first.

Thanks Kommando, I’ve had a look and ordered a 25v 22000μF to go on the lightning, I had a situation at the weekend where my mates battery had died so fitted it onto my bike and mine onto his, being 3 phase high output my bike still started within 3 kicks, however decelerating and putting the brake light on caused it to pop and bang all over the place, which wouldn’t have done the motor any favours as being EI it would be sparking during each energy pulse (or rather when the power is removed momenterally). I’ve suffered with batteries which have failed when I have least expected it to before so this is a good thing anyway.

I assume when running the bike and the battery has known to have died, is it imperative to remove the fuse to the battery? Or would there be wasted energy being used to try and charge the battery if it was still connected instead of going to the cap?

Thankyou.

batteries can be funny .
You got to remember ,
A 12 volt battery is made up of 6 cells in one case ... a series string connection .

2v + 2v + 2v + 2v + 2v + 2v = 12 volts

2+2+2+2+ ( 2 ) +2= 12 volts , but is restricted to the capacity of the smaller ...red 2v cell.
2+2+2+2+2 ( + ) 2 = 12 volts , but is restricted to the capacity of the weakest red connection between the cells .
Both these batteries might read a full voltage charge ... but not be able to deliver much power .

Yes, until you pull the fuse the alternator will attempt to charge the battery, hence the need to pull the fuse. It also means a blown fuse not from a short but say vibration will not stop the bike, had that on a Commando with std cap, you only know the fuse has blown on the next start-up when nothing works .

Hi quinten, Yup. If you know about this you can probe the fluid in the cells & measure where the "fault" is. Sealed batteries, obviously you cannot. Almost always this sudden failure to produce amps, but volts ok is an internal connection, not plates sulfated or just worn out. The old hydrometer test.... Sealed battery prevents that too. I've never cut open an AGM battery to see how the internals actually look. So far as I know all AGM are sealed.

The electronic load test is actually not very reliable in real life. We had hundreds of batteries that passed that perfectly, yet could put out no amps. In the end of the day the old "resistance load tester" was the real deal. It was said it was hard on battery. Might be, but if it passed, it was a good battery. We'd use it often. Factory demanded print out from electronic tester with VIN# entered etc. We figured out all sorts of ways to rig a test failure. Simply putting 3" long 8mm bolt between + post on battery & tester clamp. Held bolt to battery by hand. Savy techs kept a "test" battery under their bench. We learned really quick how poor the electronic tester really is. Many times internal resistance & real life, didn't match up.

Motobatt claims they have better & more vibration resistant connections inside their batteries. This makes them better & don't fail internally as easily. I don't know if that is really true or not.

Lots of guys in my riding circle of friends use them. They have a very good reputation. I hate the yellow case as you can see it on some bikes. That's the only draw back. You could always paint it. I know these are costly, but seem to be worth the cost.

Desco, What brand battery went bad on you? How old was it?

Don

Scorpion. At least 4 years old so I can't complain. It's just that I was fooled by the 12.9V.