I agree with Shane's quick test. A more elaborate approach is to develop a charge/discharge profile.
Quote:
Originally Posted by icrude
Thanks everyone. I plugged it in and it charged and stayed right at 12.7.
|
If you measured the voltage when the charger was still plugged in, then you were measuring the voltage of the charger, not the voltage of the battery.
Quote:
|
I unplugged the 110 cord and within 30 minutes it dropped to 12.49.
|
This is the dissipation of the surface charge that was mentioned above. Yes, it is expected, and a drop of 2/10 of a volt isn't really very much, and does not indicate a fault.
Quote:
|
Time to replace the batteries you guys think? I looked inside, not low on fluid.
|
I don't think you know enough about the situation to make that call yet. Are you able to measure the current being drawn from the battery when the charger is not connected? If so, how much is it?
I would suggest that you first charge the battery, then disconnect the battery from the charger and the TM, and measure the terminal voltage. Wait an hour or more, then measure it again - it will be lower. Then wait a couple more hours, and measure again. Wait 24 hours and do it again. The terminal voltage should be stabilized. Now connect the TM, or a known load, let it run the load for a few hours, disconnect the load, wait for an hour, and measure it again. Now report back the discharge current, and the voltage sequence.
Incidentally, I have never found terminal voltage to be really good indicator of state-of-charge, especially as the battery is being exercised. A better solution is to measure the specific gravity of the fluid with a temperature-compensated hydrometer. They are not particularly expensive, especially compared to the cost of two new batteries. Get one with a glass float - avoid the ones with the floating balls.
But first try Shane's suggestion.
Bill