Bad Battery?

Thanks for help. Batteries tested ok. Must be my charger.

Open circuit full charge voltage
6 volt = 6.37
12 volt = 12.73
At 13.6 it should bring them to full charge. That would lead me to suspect uneven spg in one or more cells, or possibly sulfating.

Vulcan Rider wrote:

joeshmoe wrote:
For a couple months now, my charger (not the onboard converter/charger) has been telling me "bad battery", cannot charge.

I have been very diligent about keeping these Interstates on a constant charge since I purchased them,

What kind of charger IS it ?

Applying a "constant charge" that is too high could have caused a problem.

Why are you not using the onboard charger ??

The suggestion to visit an Interstate store is a good one.

A couple of quick voltage measurements should tell you where the problem likely lies. It could be just a bad connection.

Could be, but I've tried charging them independently, not connected to anything.

the onboard charger is the standard WFCO 9something. It is NOT overchrging. I use it all the time. In fact, that may be the problem. 13.6 v is all that thing is capable of.

joeshmoe wrote:
Purchased two GC-2 Interstates back in Sept. of 2013. For a couple months now, my charger (not the onboard converter/charger) has been telling me "bad battery", cannot charge. Thinking the charger is going out, I put it on several other batteries and it does fine. I have been very diligent about keeping these Interstates on a constant charge since I purchased them, never discharging them below 50%. Do I need to check the individual cells? What should they measure?

Use a good hydrometer, preferably one with an internal thermometer.
A fully charged cell will test at 1.275 to 1.280.
The temperature of the hydrometer reading must be corrected to 80 degrees F (29C).
Draw electrolyte into the hydrometer several times to permit the thermometer to adjust to the to the temperature. A brown or grey coloration is a sign the battery in nearing the end of its life.

Draw enough electrolyte in to float the float and not touch the bottom of the cylinder.

Hold the hydrometer vertically and note the reading where the electrolyte meets the scale on the float.

Add or subtract four points (.004) to the reading for every 10 degrees F (6C) above or below 80 F (27C. Adjust the reading to conform to the electrolyte temperature.

Test each cell and note the readings. A variation of 50 points between any two cells indicates a problem with the low reading cell/cells. An equalization charge may restore the bad boy cell.
Good luck!

.

joeshmoe wrote:
For a couple months now, my charger (not the onboard converter/charger) has been telling me "bad battery", cannot charge.

I have been very diligent about keeping these Interstates on a constant charge since I purchased them,

What kind of charger IS it ?

Applying a "constant charge" that is too high could have caused a problem.

Why are you not using the onboard charger ??

The suggestion to visit an Interstate store is a good one.

A couple of quick voltage measurements should tell you where the problem likely lies. It could be just a bad connection.

Okay. Just read drewe's post. I'm looking for consistency and/or that one or two cells that are noticeably lower than the rest.

Cheap one should be just fine. You are comparing the readings on the cells, not necessarily looking for an exact SG.

mkirsch wrote:
If the battery has caps you can get a specific gravity tester from the local auto parts store and check for dead cells that way.

I have a cheap one. The kind with the balls. Not sure how accurate it is. Is there a specific +/- voltage I should be looking for across all cells?

If the battery has caps you can get a specific gravity tester from the local auto parts store and check for dead cells that way.

An easy quick check would be to compare the voltage of the two batteries to each other. Since they've received the same charging and general treatment, they should both have pretty nearly the same voltage across them. A shorted cell, for instance, would make one significantly lower than the other.