Voltage reading on Curvy?

What should the volt reading be at the battery with engine running at idle and main beam on?

Reason for asking is that I noticed the voltage will drop slowly at idle with main beam on. If the sv is idling with side lights on, it is steady at 14.2 and all seems fine. But when main beam comes on, the volt will start to drop slowly from 13.8v to 12.8v and carries dropping. It's my understanding that with main beam on the volt should be around 13.5v, am not sure why it just keeps dropping

The alternator and sv reg are in good working order.

However i do have those philips h4 xtreme light bulbs in front, are these putting too much strain on the battery/reg? Or wiring around the lights...

Cheers

Measure the voltage at idle with and without the lights on and then measure it at say 5000 revs with and without the lights on and post the four results here.

What has made you test it in the first place? Has your battery been ok since our trip?

[Sid Squid]

Originally Posted by Lucas

reg in good working order.

You sure? You previously changed one that worked perfectly.

Originally Posted by Lucas

Philips h4 xtreme light bulbs in front, are these putting too much strain on the battery/reg? Or wiring around the lights.

Is it a 60/55W? if yes then it isn't your problem as it's the same consumption as standard 60/55W, it's brighter 'cos it's more efficient.

Anyway it can't possibly have gone wrong - not after the God-like treatment it's had.

[embee]

I won't offer a judgement on whether anything is wrong in your instance, but as a general comment the alternator/generator output increases very rapidly at low speeds typically (or conversely if you prefer, it drops off very rapidly as speed reduces). These curves are not bike alternators, but you get the idea


If the demand/load exceeds what the alt can generate, the battery will be supplementing the current, and gradually the voltage will reduce as it discharges, so what you describe is perfectly reasonable.

I can't spot a stated output in the manual, but I'd expect something in the realms of 300W max for a bike like the SV, maybe a bit more on the FI bikes, but that will be at 5000rpm or more, down at 1400 idle speed it might be less than 100W so less than your demand. If the voltage rises to at least 13.5V when revved a little I wouldn't worry about it.

If your idle speed is even 50rpm low, the voltage you end up with could be substantially different to another bike.

Check your idle speed, maybe increase it a touch if you're concerned about getting stuck in traffic. Clean and lube all the connections you can get at, reg/rec connector especially since this carries all the charging current and losses here won't be recovered. Also check all fuses including the main fuse in the starter solenoid, clean the blades and lube them (dielectric grease is perfect, vaseline is fine too).

Thanks very much for getting back guys

I won't be able to test the bike for a while, but I will post test results as soon as I get a chance in a week's time.

It is a bit weird to see voltage drop slowly when waiting at the lights (after many electrical challenges over the years, I now installed a mini volt meter display at the dash.)

Sid, she has indeed been blessed

Cheers,

Lucas

[BanannaMan]

Oh dear...someone named Lucas having electric problems???


No....must....not.......tell.....Lucas......jokes.




Sorry mate, was just too much.
Hope you get the prince, I mean the bike, sorted soon.

[Spanner Man]

Good morning all.


A number of bikes with twin headlights will exhibit the same symptoms. It's down to the alternator being unable to provide the necessary power to keep up with the amount of current drain.
Two 55 watt headlight bulbs will draw slightly over 9 amps on their own. Then add a couple of tail light bulbs, panel lights, & the ignition system demand, & you have a current draw in excess of 10 amps.
Providing the battery voltage rises once the engine speed increases, then all will be well.


Cheers.

Hello

Did a volt test today, here are the results:

Lights off: @1250 idle / 14.39v
Lights off: @5000 / 14.00v

Side lights: @1250 idle / 14.30v
Side lights: @5000 / 13.90v

Full beam: @1250 idle / 13.61
Full beam: @5000 / 13.05

Does it look ok? Should I test the current too?

Cheers

Lucas

[embee]

The voltages under load look a bit low, which could be a sign of th ereg/rec dying but could equally simply be a sign of voltage drop with current demand.

The first thing I'd do is disconnect the main connectors especially the one at the reg/rec, inspect the condition of the terminals, lube with either contact cleaner or vaseline or ACF50 (WD40 at a push) and refit, working them well to ensure good contact. Also make sure the battery terminals are clean and nipped up snugly, apply vaseline to keep corrosion at bay.

Last but not least take all the fuses out and ensure clean contacts, including the main fuse in the starter relay (green thing behind right side triangle). Replace any fuses which look scabby, they can be had on ebay at a couple of quid for 25 with ratings of your choice.

After that, repeat the voltage check at the battery.

Originally Posted by Spanner Man

Providing the battery voltage rises once the engine speed increases, then all will be well.

Voltage is highest at 14.3, only when at idle.

voltage will only drop when engine speed is increase