battery problem?

[Gorminrider]

mmm. Interesting graph- I read it as two sections, the upper "Charging Rate" being the only one mildly pertinent here. It is mildly pertinent because a the voltages assumed in the graph are open-ended, while Charging Current is regulated in the example lines drawn.
That said,IMO, even at a low charge rate ,a charging battery with a regulated charging potential of 14.8 volts does not STAY at 13v,as long as it is "charging". It will stop charging when potentials are equal.Simply put, nowhere do the lines in the graph "flatten", at 13 volts
Assuming all is well in the charging system, 14.4 volt is the only " regulated" "flatline" voltage the OP will see.

[mike10]

My Batteries

I live in a mild climate. I don't take very good care of my batteries. I have had the acid filled.and gel sealed. Between 2 & 3 years is about as long as they last. My car batteries last about 6 to7 years. Anyway, what my bike batteries will do is start cranking the engine over slowly. So I put the charger on them and they pop right back up and look good. During use they drop in power and will not hold a charge. I only buy the between 40 and 60 dollar batteries. My bike starts instantly if the battery is good. I know a bad battery will do weird things and have you chasing your tail. I have a 2008 Roadstar I just replaced the battery in it. I bought it used a few months ago. It crapped out the same way as the GS1000E.

[posplayr]

mmm. Interesting graph- I read it as two sections, the upper "Charging Rate" being the only one mildly pertinent here. It is mildly pertinent because a the voltages assumed in the graph are open-ended, while Charging Current is regulated in the example lines drawn.
That said,IMO, even at a low charge rate ,a charging battery with a regulated charging potential of 14.8 volts does not STAY at 13v,as long as it is "charging". It will stop charging when potentials are equal.Simply put, nowhere do the lines in the graph "flatten", at 13 volts
Assuming all is well in the charging system, 14.4 volt is the only " regulated" "flatline" voltage the OP will see.

The title of the article that was referenced in the "Quick Test" post and which includes the subject plot.

Lead-Acid Battery State of Charge vs.Voltage

http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

Reading the Curves
The data presented here on the graphs was generated
from our set of Trojan L-16W deep cycle lead-acid
batteries. Each Trojan L-16 battery is composed of
three series connected, 350 Ampere-hour, lead-acid
cells. The graphs and the data here relates to six of
these lead-acid cells in series forming a 12 Volt battery.
Those of you using a 24 Volt system with twelve leadacid cells in series must multiply the voltage in the text
and on the charts by two. The voltage versus state of
charge (SOC) profiles will match those of similarly
constructed cells. Other types of lead acid cells, like car
batteries, lead-calcium cells, and “RV deep cycle”
batteries will have different charge/discharge curves. I
offer these graphs as examples of what to look for with
your battery. While specific voltage vs. SOC points will
vary from battery type to battery type, the shape and
relationship of the curves is similar for all deep cycle
lead-acid technologies

The family of curves are interpreted as the operating point of a lead-acid battery for a terminal voltage , current pair given the battery's current SOC. Of course as a battery is charged of depleted the SOC charges. However, a quick(3 sec) 6 amp discharge to a 14 amp-hr battery will not appreciable change the SOC. Understanding how terminal voltage is affected by SOC when under current load is the basis for steps 1 and 2 of the Quick test. Understanding the battery charging characteristics provides much understanding on how the GS charging system operates.

Therefore and to whatever the extent that these deep-cycle battery characteristics reflect the battery you might have in your GS I will interpret the chart as applying to a GS as follows:

From the chart..... in order to get a battery that is 50% discharged to exceed 13.5 V the charging current must well exceed C/5!!! Based on a cursory perusal of the spacing of other lines of constant charge rate, I would guess 1/2 the spread between C/2.5 and C/5 which is C/3.75

For the non-attentive, C/3.75 for a 14 Amp-Hr battery is 14/3.75=3.73 amps. This is very close to the maximum GS charging current previously measured and reported by me.

Therefore it should be patently obvious to even the most casual observer that a battery with a low state of charge will preclude the GS charging system from reaching the normal charging voltages as the current limited charging of the GS will only support lower voltages at lower states of charge.

Further, we can also see that the GS charging system has little capability to charge a battery even when the SOC is relatively high. A typical R/R voltage regulation set-point is specified to be approximately 14.5V. In practice many older and unmaintained charging system will fail to even provide 14.25V at the battery terminals. To see the impact of this low charging voltage we simply need to refer to the chart again........

From the figure we see that it takes C/5 charging amps (2.8A for a GS 14 amp-hr battery) for an 80% State of Charge (SOC) to get to 14.25 volts. This is also close to the peak charging current (3 amps). So ignoring charging and conversion heating losses in the battery it is clear that a C/5 charge rate will take at least 1 hr to get from the 80% to 100% SOC.

The curves are quite relevant to interpreting SOC from voltage measurements under known current draw conditions. The authors quite rightly state:

The bottom line is that the internal resistance of all
lead-acid cells changes with the cell’s state of charge.
This characteristic gives the lead-acid reaction its
particular shape or signature on the voltage vs. SOC
graphs. This signature is unique — very different from
alkaline cells whose electrolyte resistance remains
constant regardless of SOC. The shape of the lead-acid
curves makes it possible to use a voltmeter to
determine a battery’s state of charge.

It should be no surprise that the measurements in steps #1 and step #2 of the "Quick Test" are specifically predicated on the characteristics of Volts and SOC described in the article.

http://www.thegsresources.com/_forum/showthread.php?p=1272192#post1272192

QUICK TEST Diagnosis Summary:

Basically Step #1 and #2 is making sure the battery is charged and in good health. The drop should be about 0.5 volts for normal headlamp and coil load (without cranking the starter). Anymore than 0.5V drop indicates the battery is weak even though the static voltage is OK (12.7-12.8V)

[Gorminrider]

I live in a mild climate. I don't take very good care of my batteries. I have had the acid filled.and gel sealed. Between 2 & 3 years is about as long as they last. My car batteries last about 6 to7 years. Anyway, what my bike batteries will do is start cranking the engine over slowly. So I put the charger on them and they pop right back up and look good. During use they drop in power and will not hold a charge. I only buy the between 40 and 60 dollar batteries. My bike starts instantly if the battery is good. I know a bad battery will do weird things and have you chasing your tail. I have a 2008 Roadstar I just replaced the battery in it. I bought it used a few months ago. It crapped out the same way as the GS1000E.

I think you summed it up pretty well. I do best with cheap-but-not-the-very-cheapest in all my batteries...I've had exceptions to my rule, but not enough to make me buy the very best or the very worst.... and the $ seems to work out near the same.