Charging Question re: Kaw KLX250s

[YamadudeXS650C]

Hey Gents,

Please excuse me for asking a question about a bike other than an XS650, but I can't seem to find another resource this evening for this inquiry.

I'm looking to perhaps buy this 2009 Kaw KLX250s

The owner drove over to my house on it just now.
New battery.
Resting, I got 12.8v
Upon startup, I got 13.7v at idle, and when I increased the RPM, the voltage did not change. It stayed at 13.7
Turned the bike off, and the resting voltage was now 13.1, so it charged during this testing period.

Is this how modern little dual purpose bikes charge, or are my tests indicative of some sort of issue?
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[Mailman]

I just did a quick search on the internet. Kept finding links to Kawasakiforums.com. Short answer is, it’s charging exactly as intended. Everything appears to be normal.

 

[YamadudeXS650C]

Thanks Bob !
I'm a member there, given my previous ownership of my '74 Kaw 250 enduro, but it was always very tedious getting an answer to a question.
So, you found some definitive data?

(you are obviously a better websearcher than I)

 

[Mailman]

What I found were guys asking about, and talking about their charging. Here are a couple of excerpts.

Service manual says the alternator is rated for 16A - 14V @5000 rpm. That's 224 watts. The main fuse is 20A.

Ive got just a chance now to check it out. When I got it home last week I put it back in the trickle charger. I've now disconnected it and got a voltage 12~13 while not running, when I start the bike I have 13.6v.

While cranking the starter it goes down to 6~9v, then upto 13.6 once running.

 

[Mailman]

I read maybe a half dozen exchanges and they all said they were getting approx. 13.5 volts with the bike running.

 

[Mailman]

Ok I was able to find a service manual online. It shows ( if I’m reading this correctly, 14-15 v charging rate)
Sorry for any mis information.

 

[YamadudeXS650C]

Well, this is very interesting, Bob.
However, the info you present is from a 1994 model it seems (?)

Curiously, I test drove another modern KLXs recently from a similar year (2009 or so), and got charging results about the same as I got today, and the owner, who had some mechanical expertise, agreed with me that his bike had a problem...

 

[YamadudeXS650C]

I did some more searching this morning at Kaw Forums:

Three entries to my exact question regarding similar year bikes:

From a senior member who is an electrical engineer:
Ignition off -------------------~ >=12.6 volts depending on age of battery
Ignition on (light on) ---------- I would expect >12 volts
Light is 60/55W - So expect about a 4.5 amp draw.
Pushing starter----------------Something slightly <12 volts
The starter relay is connected to the main 20A fuse, so i would expect much less than 20A going to the starter (maybe half). There is also an interposing relay kawi calls the starter circuit relay so you may want to inspect that also if you fear a short.
Once started and warmed up --13-14 (manual says 13.2-14.2) volts
Expect about 5 amp draw between the headlight and CDI.
Remember the "started and warmed up" voltage is about 4k RPM, if you measure at idle, expect at or slightly above battery terminal voltage.

Okay, I pulled baseline numbers from my battery. Just to let you know, it is the orginal battery installed in December 2005 and it has been sitting for 2 weeks without a charge since the last time I rode the KLX.
Ignition off -------------------12.34 volts
Ignition on (light on) ----------11.47-11.52 volts
Pushing starter----------------9.0-9.6 volts
Once started and warmed up --Idle 1300 rpm 13.5 volts, choked @ 3500 rpm 13.6 volts
Consider my battery to be on the low end of grade or at the end of its life.

This is what i got did the voltage test yesterday
OFF---12.55 to 12.62 volts
LIGHT on--12.07--12.12 volts
Pushing starter---9.65 first time, 10.30 second, 10.40 thrid
Bike running---13.75-13.82 volts


So, it looks as if the readings I got were nominal..
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[gggGary]

Don't know squat about the KLX but while testing several solid state XS650 regulators I found variations in set point from about 13.8 up to 14.8 volts.

 

[YamadudeXS650C]

Don't know squat about the KLX but while testing several solid state XS650 regulators I found variations in set point from about 13.8 up to 14.8 volts.

Yup, and I'm thinkin' that similar manufacturing variations in the KLX regulators account for the "13.2 - 14.2 " notation above.

Curiously, the combo Reg/Rect unit on this bike looks just like the stock unit on my '80 XS650 Special, only a bit smaller.