Charging question

[tomo]

Sorry to bring up charging system queries again, I know they`ve been covered loads of times and we have the stator papers to refer to, but I am a bit confused. My GS750 has been blowing bulbs and losing battery fluid quite a bit recently, so I`ve replaced the regulator/rectifier with a Honda unit, its either from a CX500 or CB750. Started the bike up to check on battery charging. The reg/rec seemed to be doing its job, a quick visual check showed the headlight brightening up when revs increased from idle. The battery itself was a bit down on charge when I put it in, reading 12.7v on the multimeter. With the engine running, I found that taking the revs up to 5000rpm the reading was 15v, a few more revs and it rises to 15.3v but no more when revs increased further.
I noticed in the stator papers the reading should be a bit lower, but in the old forum a couple of replies to postings gave between 14.8 to 15.5v as being ok. Oh ! forgot to mention, the battery is out of my CX500, so it is a different type, but I just bought a new one for the GS which is on charge now. I doubt battery type would be a problem as the CX uses a 12v system too, and the GS runs ok with it in. Anyway, any advice much appreciated.

 

[Nessism]

You are good to go, 15.5 volts is fine. Just make sure you run a dedicated ground from the R/R to the battery post.

 

[trippivot]

What are the ampere readings? the voltage test is only half the real story.
15.00 DCV is too high unless the amperage is less than 1.0 DCA running

overcharging by a little but not enough to cause real problems. at this point the stator is just heating up the battery and vaporizing the electrolyte at an accelerated rate.

Warped lead plates comes next if the charge rate rises the expensive damage follows soon after.

I make changes if I get any readings OVER 14.8 DCV and 4.0 DCA after fully charging the battery by an battery charger. both need to be considered

if I get 14.9 and 0.7 then we just have to watch the water level more often

 

[Nessism]

Factory manual for my 550 allows 15.5 volts. With a properly fresh battery the system shouldn't push much current at that voltage though...hopefully.

 

[trippivot]

you have a genuine suzuki book that says that?

 

[Nessism]

you have a genuine suzuki book that says that?

Yup.

.

 

[Steve]

Yup, the 850 book spreads it across a page break, but says the same thing:

If you have a sealed battery, not only will you not need to check the electrolyte level, they actually thrive on a slightly higher voltage. 8-[


.

 

[bwringer]

But that's a no-load test, on a Suzuki R/R... 15.5V is certainly not the expected operating voltage.

On a Honda Reg/Rect, you need to pay attention to where the sense wire is hooked up. If there's a problem with the circuit where the sense wire is attached (or if it's not hooked up at all), it can cause the R/R to overcompensate and run the voltage too high.

For example, if you have the sense wire hooked into the tail light circuit, but there's a corroded connector somewhere upstream and it's only reading 11V or so, the Honda R/R will push the rest of the system much higher to try and get the sensed circuit over 14V.

 

[trippivot]

ok I'm on board I personally don't like to see voltage that hi. I guess it's better than too low.

 

[tomo]

Thanks everyone. I`m going to check out all the connections, but I do feel better for seeing it in black and white that up to 15.5v is ok. Most of my manuals electrical section is missing, thanks to my dog Max. Guess he hates electrics more than me !.

 

[Greg O.]

These specs suprise me because in most automotive applications anything above 14.5 volts is consider to high. But I guess the manual tells it like it is.

Greg O