Is there a danger of running a MacBook without a working battery?

Question

I have a MBP with a completely dead battery. The battery is so dead that the machine shuts off the instant I pull out the power cord.

When I want to disconnect the power, I shut the lid and wait while it invokes hibernate-to-disk and eventually switches to a fading power LED. Then I disconnect the power cord.

Is this practice putting the computer's hardware at any risk of damage?

Answer 1

Does it hurt?

Is this practice putting the computer's hardware at any risk of damage?

No, absolutely not. Physically, you can't damage anything.

Even more so, by hibernating and letting it write to disk you ensure that your current RAM data is kept (reasonably) safe even when you unplug the MacBook Pro for a longer amount of time and the battery power isn't enough to keep it in the hibernation ("standby") mode. That's why it's called "Safe Sleep".

---

Can you lose data?

Note that this doesn't apply if you've changed the hibernation mode to not write data to the disk. Check it by opening a Terminal and entering:

pmset -g | grep hibernatemode

How do you interpret the result?

• If this outputs a hibernate mode of 0, your data isn't saved on the disk itself, but only kept in RAM. If your power source goes dead, your current data is gone.
• If the output is mode 3, you're all fine. The system will store your RAM to the disk, and will power the memory during sleep.

See here for a more in-depth explanation. The manual of pmset also tells you more (see under "Safe Sleep Arguments").

---

Does it impact performance?

As DanH said in his comment above, I'd strongly suggest getting a replacement though. Why? Apple states in this support document that …

If the battery is removed from a MacBook or MacBook Pro, the computer will automatically reduce the processor speed. This prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide.

This does not apply to running on a battery with really low capacity, as the system still detects it as being there, but I probably wouldn't take it out (if it's a non-unibody Mac).