3 flashing lights on KY265 battery (M4400/E6500)

My KY265 battery (9-cell 85Wh for the Precision M4400 and Latitude E6500) has stopped working in that the laptop sees it as dead. If I press the test button, three of the five blue flights flash three times. I normally use my laptop on AC power, so the battery has had very few charging cycles. Is there a way to drain the battery and then charge it? Normally going through several charging cycles can restore a poorly performing battery, particularly if the problem is caused by lack of use rather than too much use.

 

Sounds like it's really dead. Once it gets to the point where the LEDs flash, there's no going back...you'll need to get a new battery.

 

Thanks, but are you sure that this is not a reversible state? And what criteria cause the battery to detect that it is dead? Given that the battery has had so few charging cycles, it's likely to be reversible.

 

Do you keep AC power connected when the laptop is off? If so, that may trickle charge the battery and revive it. However, since you said that you usually use it with AC power, trickle charge probably hasn't worked. Are you able to power up the laptop with the battery, or does the power button not respond?

There are many reasons why the circuitry in the battery will render the battery unusable, for example if there is a bad cell or if cell voltage has dropped to a point where recharging is unsafe. Lithium-ion batteries deteriorate with time, whether or not they are used, and heat from the laptop can cause them to deteriorate faster.

 

No, I disconnect the power when it is switched off, but I could try connecting it at night to trickle charge it. I can't power up the laptop with the battery at all; the power button doesn't respond.

Thanks for your advice. I was wondering whether to connect a 12V device to the connectors on the battery to try to drain it. Is it worth trying something like that?