Dodgy electrics - main light dims when indis on - battery?

[D O G]

Hi, another prob on my bike (1990 GS500E) is the fact that when I have the indicators on the headlight dims in time with the indicator flash. It gets dim when the light flashes, and vice versa.

It also seems to pulse when riding along - more noticably at slower speeds (say 40-50mph) than motorway cruising speeds, and also pulses more when under engine braking.

Is this the sign of a fubar'd battery?

Thing is, the battery seems pretty good - I recently ran out of fuel (kinda), and must have cranked the bike for at least 2-3 minutes in total, no sign of battery being weak.

Bit confused tbh, electrics are not my strong point. Well in fact they are probably the weakest of all my weak points. Which are many.

Thanks!

[Timmeh]

Could be a number of things, really.

First thing is to check the reg/rec output by sticking a voltmeter across the battery terminals and checking the voltage at certain RPMs.

Typically they should be about 12.5-13v at idle going to about 15v at high-mid-RPMs.

Can't remember if the GS lights run directly off the alternator though, can you switch the lights on with the engine off?
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GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you

[D O G]

[steo]

Do Timmeh's tests 1st as he's never too far away from the correct diagnosis, if your readings are up to spec for the battery & reg/rec then i'd say you have a bad earth or a dodgy circuit somewhere.

Take out the indicator bulbs, inspect & clean all the sockets plus the connections into the wiring loom. do the same with the front/rear lights. Have a look to see that all the bulbs are 12volts & the correct amperage. Take out the flasher unit, clean the spades connectors & the junction box it fits into. Check the earth from the wiring loom to the chassis & make sure you have a good connection.

[Feasty]

Don't know so much about your lights pulsing when you're riding along... but I've always found my bikes front lights pulse a little when I'm indicating, I think that's pretty normal and is just power being diverted from the front light to the indicators.

Also I've had heated grips on my past 2 bikes and when they're on during winter the front light does pulse a little. However I've never had any problems with the bikes not starting (unless I don't use them for a few weeks ).
So I'd say so long as the bike starts fine and your lights aren't being majorly affected then don't worry about it... you'll soon notice your battery is buggered when the bike won't start even after an overnight charge...
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Previous: Aprilia Habana Retro 50cc (beauty), Yamaha SR125 (fell apart), Honda XR125 (nippy little commuter), Honda SLR650 (Geewhizz), Yamaha Diversion 900S (Smoooooth) written off courtesy of a stupid escaped horse.
(7 year gap), BMW F650 (Relaxing ride). Aprilia Caponord ETV1000 (Big and bold). Yamaha FZS600 (got me in trouble too quick!).
Current: Yamaha TDM 900 (Comfy, light but big, power when needed).

[defblade]

Check, clean and tighten the earths. Almost always the problem with lights affecting each other as they tend to be earthed to the same spot, and if the earth is not 100%, one circuit starts playing hooky with another.

If it's a real problem, could be worth using the original wiring to switch a relay and give the headlights a new (and fused!) high capacity feed from the battery.
____________________
Honda Varadero 125cc => Suzuki Bandit 650 33bhp => 77bhp =>
BMW K1200R Sport 163bhp => Aprilia Shiver GT 750 95bhp

[smegballs]

My GS is even weirder.

The headlight gets BRIGHTER when theres more electrical load!!

eg brake light goes on and the headlight brightens up..

Any ideas what could cause this....?


/hijack

[defblade]

[smegballs]

Bad Earths seem to be right bastards....

And they seem to have really weird and wonderful symptoms!

Dont suppose intermittent charging would be another sign of these little devils?




Rich

[defblade]

Less likely I'm afraid as the charging circuit should be pretty heavily and directly connected to the battery* and so an earth problem here would probably be giving you fun with every single electrical system on the bike.



*I should point out that my experience is in car electrics, I'm quite new to bikes; whilst I'd be amazed if the lighting problems mentioned aren't down to bad earths (and the next suspect is worn/broken/shorting wiring), once we're into charging circuits and so on, I'm going on general priciples.
____________________
Honda Varadero 125cc => Suzuki Bandit 650 33bhp => 77bhp =>
BMW K1200R Sport 163bhp => Aprilia Shiver GT 750 95bhp

[smegballs]

Ok my symptoms are:

Intermittent Charging - Sometime about 13.5V other times about 12.4-12.9V. Never overvoltage

Headlights go dimmer when throttle is blipped, normally they would get brighter! Accordingly voltage across the battery drops from say 12.6V to 12.3 V when throttle blipped.

Ive just run thickish 17Amp cable from the headlight earth to the frame, from the reg output to the frame and a double length from the battery to the frame.

Ive made a clean earth connection and cleaned all the new earth connections.

Earthing for vital systems now should be OK I would of thought, anything else to check?

Sorry for stealing your thread Damofo but hopefully something good may come up for you


Rich

[MattEMulsion]

[smegballs]

Hi there, just been out for some more tests in the garage.

Ive been testing at two points mainly. The positive terminal of the battern and the positive terminal of the regulator.

My first conclusion was thus. The voltage between the + and - terminals is less when open circuit, when reg is plugged in the voltage between reg terminals increase.

At tickover the voltage between the + reg terminal (plugged in) and battery earth was 13.5V. At the same revs the voltage between battery + and battery earth was about 12.6V.

So there is a difference between the rectifier + and the battery +. Does this indicate maybe a break in the wiring between the reg+ and the battery +, or the drop due to the batteries internal resistance?

Also I found an anomaly with the revs. I used the tickover adjustment to slowly increase the revs. At idle the voltage between reg+ and battery earth is 13.5V. As the revs are slowly increased this voltage rises to about 14.3V. As the revs continue to rise, the voltage starts to drop until it is below 13.5V and into the 12.xx V range.

My tacho cable is broken so I cant be certain at what revs the voltage starts to drop, I would say from ear maybe 4-5k. I assume this indicates a faulty coil somewhere along the line which is breaking down at higher revs?


Cheers for all your help

Rich