Just a dead battery?

[John Bates]

Hi folks, this thread just woke me up from my winter hibernation.  I couldn't resist replying.

I checked my battery voltage at different rpms and here is what I measured:

1000 rpm 12.85 v
1500 rpm 13.95 v
2000 rpm 13.75 v
3000 rpm 13.45 v
4000 rpm 13.25 v
5000 rpm 13.25 v

Battery temp. 44 deg F.

I used a recently calibrated voltmeter and double checked my measurements, so I'm reasonably sure these are good numbers.

I think any of these voltage levels will cause current to flow into the battery because they are all above the voltage of a fully charged battery (about 12.6 v).

It looks strange to see the highest charge voltage at a fast idle and then falling off with increased rpms.  I don't know what to think about that.  Maybe my R/R is a little out of kilter.

[scratch]

Could the battery have been needing the charge at (that time at) 1500rpms and then less as the rmps went up (,as time went by)?

[John Bates]

Could the battery have been needing the charge at (that time at) 1500rpms and then less as the rmps went up (,as time went by)?

There definitely was some change going on.  My initial readings, immediately after starting, were high, (as much as 16 v.) up to 3000 rpm.  By the time I got to 4000 rpm the voltage had settled in.  The next set of readings, which appeared pretty stable, is what I reported.

[RedShift]

Great data John.  Thanks for posting.

I recall my data to be a bit different but not by much.  I'm not an electrician, but I understand that Watts (Power) = Volts (Pressure) x Amps (Flow).  From a previous post, I recall John offered a Suzuki reference where Peak Power was offered around 5000 RPM, so it's reasonable to imply the charging circuit will ramp up to full energy generation with engine speed. 

Thinking about this, is it likely that you'd get a lower voltage if the battery is in need of charging?

[Cal Amari]

Thanks for posting those figures, John. Can you provide some more information for us? For example, do you know what the battery voltage was BEFORE you started the engine? How old is the battery, and what general condition is it in? Can you provide readings for the specific gravity of each cell before and after you measured the voltages? I'm curious to know if you saw those figures with a strong battery, or one that was slightly under-charged.

If the battery was slightly undercharged before the testing began, that could account for the voltage reading jumping to 13.95V when you came off idle (1000 RPM), and the subsequent drop in voltage as the battery began to take a charge at the higher RPMs.

Either way, more to think about, and I really appreciate you taking time to post those results. My GS is now on loan to a relative (who took it to ride on his vacation), so I won't be able to test it until it is returned.

[John Bates]

.........................
Thinking about this, is it likely that you'd get a lower voltage if the battery is in need of charging?

I would think so.  I would expect it to rise as the battery charged. My battery did show a low voltage before I made the readings, even though it was on a charger.  I think my charger is not doing it's job.

The battery is three months old and should be fully charged as I have been riding once/twice a week weather permitting.  When not riding the battery has been on the charger.

I'll make sure the battery is fully charged, then do another voltage check.

[RedShift]

That's what I thought.  If I recall correctly, a charged battery should give close to 12.6v.  If it's not drawing much (fully charged), given relatively low wattage from the generation circuit at idle speeds and low current draw elsewhere, the voltage should be relatively high.

I've shown less voltage than your data shows, John, but not by much.  I had to get over 2000 RPM to show 13v across the poles.  But the good news out of this thread is that I think I've discovered a way to imply battery health without the need of an Ampmeter!  Excellent!!! 

[Cal Amari]

RedShift is right about the voltage produced by a fully charged battery; each fully charged cell in a 12V battery should produce about 2.1V under ideal circumstances. Therefore, all six fully charged cells in a 12V battery should produce ~12.6V. I'm never satisfied with simply taking voltage readings on questionable batteries; I prefer to check the specific gravity of each cell to be sure all are healthy.

In extreme circumstances, I've drained flaky batteries, flushed them with distilled water to remove sediment from the bottom of the battery case, then refilled them with fresh electrolyte; I've saved a fair amount of money doing that over the years. I dump the old electrolyte into a large plastic wastebasket which contains about 4 gallons of water, and about half a box of baking soda (to help neutralize the acid). I then add more water to the wastebasket, to further dilute the electrolyte. I use litmus paper to indicate when the mix is neutralized, fill the basket nearly to the top with more water, and use the contents to rinse the patio. No visible harm to the flagstones yet...

[groff22]

Ok quick noobish question... Would well water suffice for refilling the battery cells?  I understand distilled water to be evaporated water... What do you guys use when your batteries are low?

Thanks

[galahs]

I'd imagine "Well Water" would have too many minerals in it.

[groff22]

what about bottled water like aquafina or some jazz like that? demineralized, say reports.

[NiceGuysFinishLast]

what about bottled water like aquafina or some jazz like that? demineralized, say reports.

demineralized =/= distilled.

Go to the grocery store, buy a gallon of distilled water for about $1.08. If something's worth doing, it's worth doing right... My $.02