Battery question

[Spuds1234]

Out of curiosity (and a bike thats not working right), would a bad battery thats not holding a charge cause the tail light bulb to blow consistantly while the engine is running?

[YellowDog]

Out of curiosity (and a bike thats not working right), would a bad battery thats not holding a charge cause the tail light bulb to blow consistantly while the engine is running?

No
:no: :no: :no: :no:

[onearmedbandit]

Shouldn't do. Your charging system is providing the power for lights etc.

[davereid]

Out of curiosity (and a bike thats not working right), would a bad battery thats not holding a charge cause the tail light bulb to blow consistantly while the engine is running?

Most bulbs can run quite a significantly higher voltage than the nominal voltage of your bike. So even if the battery was duff, a single light blowing lots is likely caused by vibration.

Lose earth rattling, tail light not mounted securely, look there first. Plus, its cheaper to look there than it is to buy a battery.

[YellowDog]

If you get yourself a battery tender for about $50 on TM, you can keep your battery topped up and save it getting discharged to a state of damage where it will no longer hold charge.

You blowing tail bulb is likely to be realted to short of some kind, though they really don't like a flickering voltage going through them, which is what your duff battery is doing.

Good luck.

[Spuds1234]

Swell.

A quick check of the multimeter accross the battery terminals tells me the battery is charging, so I guess I'll have to delve a bit deeper.

If there was a short to earth wouldnt that blow a fuse first. Although the tail light is on the same circuit as the starter motor so its fused with a 20A fuse. There are no issues with anything else on that circuit (except for a flat battery not being able to start the bike).

What are the most likely causes of this?

[Spuds1234]

Wow not sure how I missed 4 replys to this thread this morning.

I dont need a battery tender, I ride my bike every day.

Why would tail light bulbs suddenly start to go from vibration? Its never been a problem before on this bike (since new). Now suddenly the battery wont hold a charge and its blowing bulbs.

Oh well. I have a new battery arriving today so I'll see how that goes and replace the tail light bulb again and see what happens when the engine is running.

Thanks for the replies guys.

[Juzz976]

Did u check the AC component of your charge voltage, generally your going to have an AC waveform superimposed onto your DC. as more load is taken the regulation of the DC output reduces (increase in AC fluctuations).

Its posible your regulator is either allowing transients (surges/spikes) or the Alt AC peaks to go through on 1,2 or maybe all of the phases from the alternator to the DC distribution.

If your battery plates have sulphated then the internal resistance is higher giving less charge at float voltage and also less ability to soak up or drain off these peaks.

Esle a bad connection in the socket or wiring close to the lamp could be heating up, now this is not enough to burn out the filament but its reduces to thermal conduction of the conductors supplying the filament, thus the filament is running hotter and may be making it go brittle and melt. <- more likely as only 1 lamp is blowing come to think of it. Also loose connection could cause thermal creep from constant contraction and expansion of filament from the repeated on off.

[Spuds1234]

Lol I was testing the ac side of the rectifier this afternoon and my multimeter ran out of battery. Before it went flat it was putting out a steady 25Vac.

I think I was testing the right wires, although there were 4 wires rather than the 3 I was expecting.

Im going to retest everything when I get my new battery and see whats up then.

The lamp holder itself is fine. No signs of damage at all.

[Juzz976]

and the connector?

Maybe u just got a bad batch of lamps

make sure there isnt too much AC voltage at the battery when charging, check at idle and at rev.

[Spuds1234]

Do you mean DC voltage at the battery?

Its at about 14.6Vdc at idle and 14.8Vdc at 5000rpm.

I would have thought that the idle value should have been lower but according to a electrical diagnosis flow chart its ok.

[Juzz976]

No I mean AC, a meter will determine a DC voltage based on an average.

A small amount of AC may come through the regulator as well

|12V ---------- 12V DC ~~~~~~ 12VDC with 0.5V AC Ripple
|
|
|0V -------------------~~~~~~ AC Volts (say 0.5V)
|
|
|-12V -------------- -12VDC

The more ripple VAC divded by VDC = % Regulation as load increases regulation falls.

The rectifier gives out a pulse DC, the regulator limits the peaks and a battery or capacitor is used to filter out any residual AC waveforms.

[Spuds1234]

I'll check it out once the battery is charged again lol. Its on charge now, should be right in an hour or two.

[Juzz976]

This is DC with AC Ripple, the reverse is AC Voltage with DC offset.

the meter reads the average voltage in DC mode and measures peak to peak on AC mode.

If you AC component is as much as your DC..... 12V DC with 12V Ripple, your peaks will be
+28.97V and -4.97V (peaks are √2 (1.42) x the rms value). and in DC will only show the offset of 12V.

[Spuds1234]

So I should measure the AC voltage across the battery while the bike is running if Im following you correctly?

I did this and it read 32Vac. I switched the meter leads around and it read 0. Im real confused lol.

[Juzz976]

32V would be very bad, getting 0V doesnt sound right after the initial reading. leads either way around in AC mode will give same value. Depending on meter of course, maybe it can only de couple one way according to the offset.

Check again as 32V is definate not good, but would be unlikely if alt output is 25V.
Unless its a 4 wire star alt, and u measured from 1 phase to neutral. and your phase to phases is like 42V

[Spuds1234]

I put you wrong with the alternator output. Its about 66V between all 3 phases. I had the wrong wires.

What I was testing when I got 25V must have been something different. Probably the wires coming out of the RR. There were 4 of them 2 of a blue colour and 2 of a red colour I think.

I cant remember if there were 25V between a red and a blue or a blue and a blue now though.

I'll retest the AC voltage shortly. If I do get a high value again is it likely that my RR unit is on the way out?

[Juzz976]

yes or its not earthed properly, its most likely a shunt type, meaning it drains off current back to ground to limit the voltage.

I'll draw A pic for u when i get home

[Spuds1234]

Well the new battery has solved all my starting problems which is nice.

Now to get to the bottom of the RR putting out 32Vac and the tail light bulb blowing (which I wont be able to check again for a day as the local servo was out of bulbs this morning).

Would this high AC voltage be likely to shag my new battery in short order or do I have a bit of time to get it sorted?

At some stage I'll try another meter and see what I get. My meter is only a cheap one.

[Juzz976]

Yep, you'll notice the acid will boil out the overflow tube. If you can use another meter to check, also make sure the range wasnt on mV cos 32mV would be ok.

This can also cause damage to other components, you cdi should have its own regulation built in but the pulsing may eventually kill it.

Sorry drawing is work in progress as its evovled into something that will be of use to many people with reg/alt problems.

[Spuds1234]

Both batteries Ive had have been of the sealed variety as it is on about a 45° angle.

What are the signs of the battery boiling if its a sealed battery? Are there any tricks to stop/prevent the battery from boiling?

The meter only has a 200V and a 500V setting for AC. I still only get the 32Vac reading when I have the "positive" lead on the meter hooked up to the positive terminal and the "negative" lead hooked up to the negative terminal.

If I switch them around it just says zero.

I got a new tail light before from repco and its still good after a quick 5 minute ride whereas before it was blowing after a minute or two so Im going to keep a spare on me and see how things go with that.

[Spuds1234]

I think my meter is stuffed. I figured that an easy way to test it would be to put it on the AC setting and put it across the old battery with nothing connected to it.

It read 28Vac with nothing connected to the battery, and 35Vac with my battery charger connected. So Im guessing that my RR is probably fine and my meter has put us on a wild goose chase.

[neels]

I think my meter is stuffed. I figured that an easy way to test it would be to put it on the AC setting and put it across the old battery with nothing connected to it.

It read 28Vac with nothing connected to the battery, and 35Vac with my battery charger connected. So Im guessing that my RR is probably fine and my meter has put us on a wild goose chase.
Yep, your meter is dodgy, should read the same both ways around and nothing across a battery.

If you're getting 14.6 VDC on your battery that's about right, so your bulb shouldn't be blowing. Seem strange to only be the tail light though, if you had too many volts running around then I'd expect your instrument, headlight and indicator bulbs to go as well. I'm trying to think of a wiring fault that could cause the bulb to blow but can't really think of anything. You could try turning it on and see if it blows when you put the brakes on instead, if it does that would make it really confusing.

Edit: I've got a good multimeter at my place if you want to brave the dodgy roads and bring it round for a look.

[Spuds1234]

Yip its an interesting problem thats for sure. Should be sorted soon enough but in the mean time Im just going to carry around a spare bulb or two.

Thanks for the offer of the meter. I'll just pop in and see Wayne though as I dont know when I'll be heading into town again. At the moment there's a nice wee gravel detour around Lineside road. Im hoping the road through to Ohoka is open as that should be a little less gravelly.

[Spuds1234]

Just an update incase anyone is interested.

All the electical problems on the bike seem to have fixed themselves with a new battery. Although I have yet to test the R/R Vac output.

I will edit this post when I have sometime in the next week.