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XS400SE81 "Static" current form battery too large?


oscar_m
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Hi guys,

I'm trying to run my bike after long winter (still snowing though) and I just do a some checks here and there.

I was measuring current drawn from the battery when "off" just to check for excessive current, but it was ok. I have turned the key to "ON" - neutral&oil lamps went on and I could measure 3Amps to negative battery terminal.

I did fast calculations - neutral+oil lamp: 2x3.4W @ 12V -> 0.6A, even if I add something extra it's far from 3A. I have disconnected the whole "indicators box", but it still draws 3A. I've checked for the resistance at disconnected battery and disconneted indicators box - it's roughly 3ohms no matter what.

The only thing I could find with such resistance is starter relay coil (~3ohms) but that would give max 2A and according to electric chart I could disconnect it via "kill switch" - which is not happening. I guess that ignition coils could also look like that, but I was trying to move the engine with kickstarter to release contact breakers and that didn't change much.

So is this 3A too much or it's ok or should I look for a short circuit etc? Any suggestions?

regards

Oscar

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  • Moderator

With the ig on you will be suppying power around the bike. Energising ig coils and such.

It doesent sound to drastic to be honest. 3A is not a lot on a 12v system. My headlight will take approaching twice that alone.

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you'll have electronic ignition which needs a healthy 12v and will draw current. Don't leave it on too long as the bike is designed to run not sit with ignition on!

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The point is that current doesn't just "go" somewhere, you need a point where it is consumed. Anyway, from what I understand from this:

http://xs400.net/wb/media/faq_anhaenge/schaltplan_4G5_bunt.jpg (good replica of Haynes)

is that I don't understand where it exactly goes :) I was just wondering if this doesn;t really make the cold start pretty hard.Turning that cold engine with stiff oil is pretty demanding and any additional, unnecesary current just makes it worse.

Anyway - I'll play around and see, if it can be helped or is it just normal.

regards

Oscar

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you don't say where your from, but the US bikes have relays for neutral and side stand as well as one for the headlamp which has a diode in there.

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Just disconnect coils and things then see what's taking the power.

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Just disconnect coils and things then see what's taking the power.

don't if you have electronic ignition as it will affect the TCI and may break it

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I thought they were old fashioned points on the 80-81.

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hi there,

nope - no TCI, just contact breakers.

Actually I managed to find the answear in the german wersion of workshop manual - it is voltage regulator that shunts this additional winding to ground (see again on the stator widings here: http://xs400.net/wb/...an_4G5_bunt.jpg )

The voltage regulator is a 2-stage transistor curicuit, by default connecting one end of this winding to ground, "shorting" battery to ground. I'll try topost a picture later. It seems that this ~3ohms and ca 3 AMps is just normal.

regards

Oskar

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Put a spanner on the side of the generator. Does it stick to it with the ignition on and not when the ignition off?

Thats where you power is going - it has a field controlled generator

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Put a spanner on the side of the generator. Does it stick to it with the ignition on and not when the ignition off?

Thats where you power is going - it has a field controlled generator

good call, forgot about that :)

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  • 4 weeks later...

Hi guys,

as promised I put here a picture of a "spannungsregler" - a voltage regulator:

http://imageshack.us/a/img827/1012/regulator.jpg

that works with floating winding here:

http://xs400.net/wb/media/faq_anhaenge/schaltplan_4G5_bunt.jpg

If the volatge rises above specified voltage the T2 shuts T1 down thus reducing current through the winding, which results lower voltage output.

The downside is that the static currents flow through "green" cable when engine is stopped and it was those 3Amps I have been looking for. At ignition ON and engine off I measured ca.1V on green (which seems ok).

regards

Oskar

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