Voltage Ups and Downs

1308 Views 20 Replies 10 Participants Last post by akaPieta, 4 d ago

Buzzzer

Discussion Starter · 15 d ago

I haven't posted here in a while but noticed something recently with my '09. At idle the headlights drop and come back up, constantly. When revved/riding they stay the same. Last night I hooked the voltmeter up to the battery terminals and at idle it would go up and down from 14.5 to 13.5 volts. 2-3000 and above RPM's it stays at around 14.5 volts. Anyone else have/had this issue, or is it a non-issue?

I've had the bike since new, it has just under 54,000 miles on it. The only thing that's ever been hooked up to the electrical is a 12 volt "cigarette lighter" for charging a GPS (and that isn't being used 95% of the time, including last night). The battery is around 3 years old (gel type). I checked the battery this morning and it reads 12.8 volts.

I've never noticed this before but do know the headlights dim some at night when coming to a stop. Just weird seeing this. I've searched, and read many threads on this on the forum and can't find one that exactly describes this. Any suggestions?

Thanks in advance!

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DesertBike

· #2 · 15 d ago

Have a 2004, had a charging system concern recently so have had cause to look into this topic.

If you like, I'll see if my headlights dim at idle. I haven't been riding near or after dark recently, so if they do, I don't notice.

Charging voltage, as measured at battery terminals, generally varies from something like 13.7V at idle, to a steady 14.5V at 2000+ RPMs.

Are you using the stock wiring for headlights? I ask because I use an Eastern Beaver headlight relay harness on my 2004.

sabrecanuck

· #3 · 15 d ago

I installed a $4 volt meter on a home made dash to monitor voltage on my 2004. When running, the bike is always at 14.5+ when running, idle or not.

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Solarguy

· #4 · 15 d ago

I have the last of the gen 1 bikes (2011). I have not one, but two aftermarket voltmeters. One is a verified good one that I have hooked up directly to the battery with it's own rocker switch so I can check battery voltage when the bike is off. On that one, voltage at idle is lower than at speed. But at idle, the voltage is pretty stable. And at speed, the voltage is also pretty stable around 14.5.

The other voltmeter was a freebie when I installed a tire pressure monitor system. It did not get wired straight to the battery. I tapped something else up front somewhere (I don't recall what). On that voltmeter, the voltage varies dramatically, both at idle and at speed. The point being, the voltage is different depending on where you check it on the wiring harness and what other loads share that circuit.

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DesertBike

· #5 · 15 d ago

Correct, you have to measure consistently and correctly, or you'll only waste time chasing false leads.

I always measure charging voltage either at the battery terminals, or on a circuit that comes off the battery & doesn't connect to any other loads. In the latter case I will check for any voltage drop caused by the wire run.

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Rolex

· #6 · 15 d ago

Have a good look at the battery and get it tested, a bad battery will give bad results.

Check the cables are tight, they do work loose on bikes.

Can you hook up a second battery in line and do the test again ?

The big plug on the left side above the radiator could be starting to go bad open it up and clean the contact points.

I my younger days when we topped up the fluids in our batteries I discovered if the electrolyte was low the headlights would change more with the RPM's

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dmfdmf

· #7 · 15 d ago (Edited)

Buzzzer said:
I haven't posted here in a while but noticed something recently with my '09. At idle the headlights drop and come back up, constantly. When revved/riding they stay the same. Last night I hooked the voltmeter up to the battery terminals and at idle it would go up and down from 14.5 to 13.5 volts. 2-3000 and above RPM's it stays at around 14.5 volts. Anyone else have/had this issue, or is it a non-issue? Any suggestions?

I bought a used 2007 Wee and installed a voltmeter. After a couple of years of riding I got familiar with the normal pattern of voltage and not so much the actual or exact numbers. Cruising, twisties, starting and stopping, etc. all had recurring patterns. One such pattern was that at idle it would sit around 13.6-13.8v but would pop up to 14-ish once I took off from a stop. One day I noticed that it was hanging around 13.8v a bit longer than normal when starting from a stop. I tested the charging system per the manual and everything was still in spec and I wasn't having any starting issues or dim lights, etc. But because the normal pattern had changed I decided to measure the stator voltages (they are AC not DC and feeds the regulator) and found one of the stator winding legs was low compared to the others and out of spec. So I replaced it before it failed and avoided a breakdown.

So if this dimming headlight issue is new or gotten more noticeable over the years then I would measure the stator output to verify it is ok (do a seach). Also, because of the design, the stators are actully a wear item and MTBF and the expected lifetime (guestimate based on reports here) is probably around 60K miles with a huge variant of about 30K miles (i.e. some die at 30K, some last till 90K, most die around 60K miles). Since OPs bike is near 60K the stator may be on the way out.

Regarding voltage measurement. I always install a voltmeter on my bikes. I've had both direct to battery and have used the spare headlight circuit freed up with an Eastern Beaver relay. What matters is the voltage at the battery so I'd measure the volts at the battery with a voltmeter and compare it to the volts shown on the gauge to get the diffence. When wired direct to battery the delta was only 0.2v which I ignored but when using the spare headlight circuit the delta is 0.9v so I'd just mentally add 1.0v to the meter to compensate for the voltage drop in the wires.

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DesertBike

· #8 · 15 d ago

Good to know about the expected stator life on the original recipe Wee. MIne from 2004 is still bang-on within spec @ 50k miles, but I'll plan for rewinding eventually. Hope Custom Rewind is still in business by then, or I can get it rewound somewhere else.

Rolex

· #9 · 15 d ago

The earlier bikes had a lower output from the stator, this meant the stator had a longer life expectancy.

Less unused power dumped back.

ballison404

· #10 · 15 d ago

my 2008 has the same issue. voltage at idle is jumping all over the place +/- 0.7 volts or so but really consistent after taking off. I ended up getting the eastern bever headlight relay kit and my lights have been steady since. did a 4 hour trip the other day and didnt have a single battery issue so im hopeful things are fine.

the stator measured fine, but i wasnt able to check the rectifier without disconnecting some wires that were soldered directly to it from the previous owner so im not sure its condition.

dmfdmf

· #11 · 15 d ago (Edited)

DesertBike said:
Good to know about the expected stator life on the original recipe Wee. Mine from 2004 is still bang-on within spec @ 50k miles, but I'll plan for rewinding eventually.

I hope it was clear that 60K miles is not an official spec but a guestimate, or as engineers like to say a WAG (wild ass guess). The killer is the variance of +/- 30K miles means your stator can go anytime. So keep an eye on the voltmeter and if the voltage patterns change then check the AC volts as the DC volts can still be in spec for a while before failure.

Hope Custom Rewind is still in business by then, or I can get it rewound somewhere else.

I hear that rewinds are hit or miss. When my stator failed I wanted to go with a series R/R which are better than the shunt R/R but I didn't want to drop $350 on a new Suzuki stator. Switching to a series R/R is only a good idea if you install a new stator too as it can fry a used stator.

So I compromised and upgraded to a new mosfet shunt R/R (better voltage control but still a shunt type that abuses the stator insulation) and bought a used stator from an SV racer. He had a whole cabinet of rashed side cases with stators. So far that used stator has been fine but I could go through 3 used ebay stators for the cost of one new one so that is my strategy on stators and why I stuck with a shunt R/R.

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DesertBike

· #12 · 15 d ago (Edited)

@Buzzzer I tried it in my garage this afternoon and did notice a vanishingly small dimming of the headlights at idle as compared to higher RPMs. I suppose it relates to the small voltage difference of idle vs 2000 or higher RPMs - as much as 0.7V.

I tested my stator recently and it's 100% in spec, so I'd say what you are seeing is normal.

It's worth doing the shop manual stator tests to reassure yourself. Fairly easy to get at the relevant connection.

It's more work to test the regulator-rectifier, as you have to move stuff (like the fuel tank IIRC) to get at its terminals. However if your stator is healthy and you're measuring the charging voltages mentioned from idle on up, your R-R is probably fine.

Do add a voltage monitor of some sort to the bike, so you can easily observe any trends in charging voltage. Then you'll likely catch a failing stator in plenty of time to do something about it, rather than suddenly have a bike that won't start after you've stopped for gas.

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Buzzzer

Discussion Starter · #13 · 15 d ago

Thanks for all the replies, I appreciate them!

As far as headlights and wiring goes (as well as stator/rectifier) it's all original as I haven't had to do anything with it, yet... I do have the shop manual so I'll do a little more digging this weekend. I need to stress test the battery a little more as well. As far as the voltmeter measurement goes I did that at the battery terminals.

Who knows, maybe the battery is on it's way out. Guess it wouldn't be surprising as the batteries of today don't tend to last too long nowadays...

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Rolex

· #14 · 15 d ago

You do need to fit relays to your headlights before your starter button gives you trouble.

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akaPieta

· #15 · 7 d ago

I had stator failure on my '11 650,

Replaced with a new OEM Stator, also did the SH847 OEM Rectifier, no dimming of lights at all. Still to install my Voltmeter but so far 2000km later bike is running like a dream, measuring 12.8/9v resting ignition off.

My starting procedure is as follow,

Push the starter button, switch on ignition (This way the headlights are already off), pull clutch to start.

I had another V-Strom enthusiast teach me this, dont know if it really helps, but this way the headlights are off already and it kind off makes sense to me. Haven't had any issues thus far, with wiring.

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bildinsh

· #16 · 7 d ago

Adding to this thread - Would you consider 12.8V on a warm engine standing idle in traffic , but 13.8-14.2V running around 5-6k without additional load to be normal behavior on a 2008 ABS bike or should I be concerned.

Ive already had charging problems, and my stator was re-wired and restored.

akaPieta

· #17 · 7 d ago

bildinsh said:
Adding to this thread - Would you consider 12.8V on a warm engine standing idle in traffic , but 13.8-14.2V running around 5-6k without additional load to be normal behavior on a 2008 ABS bike or should I be concerned.

Ive already had charging problems, and my stator was re-wired and restored.

I am no expert. But that 12.8v seem to bother me.

dmfdmf

· #18 · 7 d ago

bildinsh said:
Adding to this thread - Would you consider 12.8V on a warm engine standing idle in traffic, but 13.8-14.2V running around 5-6k without additional load to be normal behavior on a 2008 ABS bike or should I be concerned. I've already had charging problems, and my stator was re-wired and restored.

Hard to say with a rewired stator. What is the voltage difference between your voltmeter and the battery? If it is greater than 0.2v then it is probably fine as 13V at the battery is enough to charge the battery even at idle. When wired directly to the battery my voltage drop is 0.2v and when using the spare headlight wires (from Eastern Beaver relay) my voltage drop is 0.9v. Measure the drop and add it to your numbers as the voltage at the battery is what matters. I also have noticed that volts are higher when cold or on really cold days (due to increased resistance when warm?) so lower when warm is not unusual.

Assuming the repair is fine and was done a while ago and you have had no issues just monitor and learn the patterns and if the pattern changes then investigate.

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bildinsh

· #19 · 7 d ago

I have the Aliexpress Voltimeter attached directly to battery, altough its not the only accsesory attached to it, so maybe im losing some volts along the connection. I have noticed that on cold starts voltage on idling bike is on higher side, low 12.8 is usually in standing traffic when bike has been ridden for a while and voltage goes up even with the slightest bump on throttle.

Stator was re-wired 20000km ago.

Gert

· #20 · 6 d ago

What is the idle speed when the reading is 12.8V?

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