RGF said:
What does the Red bar in battery condition really mean? Is it the battery is bad or just borderline?
Old & well used lithium batteries will put out the required voltage when they have plenty of charge but, when the get to lower levels of charge (ball park figure of 15% and lower) the voltage drops. This leads to (for a personal example I've had - a lot) my old phone powering down unexpectedly if it tries power-hungry stuff when the battery is low - there might be 12% left in there but fire up a demanding game and it'd shut down.
I charged the battery every night and I guess it took about 2-3 years before I noticed any issues with it shutting down (apart from maybe gobbling up the last 20% quite quickly).
Looking at the list below, I expect a camera unexpectedly powering down, despite showing some battery capacity left, is the reason for the red square - re-conditioning will give more capacity but as far as I know won't help with the premature shutdowns:
3 Green Squares: Battery is providing full performance each time it’s charged
2 Green Squares: Battery still producing good power each time charged, but not to the level of a brand-new LP-E6 battery pack
1 Green Square: Battery is nearing end of its useful life; full recharge will not deliver performance matching a new LP-E6 battery
1 Red Square: Battery has reached the end of its useful life, and should be discarded and replaced with a new LP-E6 battery pack. Recharging or re-conditioning will not enhance its performance.
Given that the premature shutdowns would only happen when the camera draws more power, I would only expect this to be an issue for video users, not stills shooters.. This may be why the other poster isn't seeing apparent differences between his batteries.
While I'm banging on, pro tip for lithium battery life is to:
- recharge before it runs out - a battery that's charged twice as much because it never fully drained will be in better than the same battery that was charged half as much but used until it ran out (the charge-discharge cycle is not how many charges it's had but adding up how many it would have had if all the partial charges, because you topped it up before it had fully discharged. Something in either the device or the battery makes the device power down before voltage goes too low but it's better for the battery's long term health not to get near that state).
- Don't leave undischarged on the shelf for long periods of time (and be aware they self discharge). For storage, approx 40% is said to be best which implies regular partial charges so it hovers in the 40% ballpark. I cycle my lithium batteries so they all get used as much as the other.
For further reading on devices shutting down early due to the battery not putting out enough voltage see the recent news stories about Apple's phones throttling back when on older batteries.