Tip: More Battery Tips right from a battery engineer

This information is extracted from an IAMA from Reddit.com, here. I hope you find it useful.

If I keep my laptop plugged in 24/7, is that damaging to the battery (or the laptop)?

No, as long as your laptop doesn't get really hot. heat degrades teh battery.

For extending rechargeable battery life is it better to wait until the battery is a 0% to recharge, or doesn't it matter?

You can extend battery life slightly for lithium ion batteries by not taking it all the way down to 0%, but it doesn't really matter. The reason is the impedance increases as you get closer to 0%.

To optimize battery life should one leave a laptop, with a lithium ion battery say, plugged in while the battery is fully charged?

Doesn't matter. The battery isn't in use when the laptop is plugged in. But, heat DOES matter. If your laptop gets really hot for some reason, it will degrade the battery even if its plugged in all the time.

I have heard a bunch of different stories from people telling me that its good to completely drain your lithium batteries occasionally and others who tell me that its bad for the battery... Are people telling me bullshit stories or is their truth behind them?

Literally completely draining the battery as in taking it down to 0 volts is bad. Taking it down to the low voltage cut-off (as in laptops or consumer devices) doesn't matter. So what I'm saying is if you have a bare battery with no circuitry, don't ever take it down to 0V. If it's in a smartphone or laptop, then it doesn't matter.

I've heard using rechargable batteries is best on devices that drain them quickly (cameras) and not as good on devices that last forever (remotes). Is this true? I have since been spending a bit on the Energizer and Duracell rechargable and was wondering if they are really worth it.

No, there's no truth to that. The only real difference is cost.

Whats the best way to store NiMH rechargeables long term for emergenices (primaril AA and AAA)?

Cool and dry place, like inside your bedroom or something. You should use lithium ion if you're storing batteries long term.

Is there anything I can do to maximize the life of my power tool batteries. Specifically 18 volt ni-cads (DeWalt brand) They're about $60 a piece and I find that some last for years while others go bad in months. I don't keep track of individual cycles run since I usually have about a dozen on hand and they get switched between different tools. Thanks for any advice you have.

Couple things you can do: 1. Store them in a cool, dry place. The hotter your garage is, the shorter they'll last. 2. Make sure you're using a charger for NiCads. The algorithm for charging NiCad is significantly different than any other battery chemistry. This is the most important one. 3. You can apply a high current pulse to clear the battery of any dendrites if you suspect the capacity is decreasing much faster than you'd normally expect.

Sadly there isn't much you can do once the cells are built into battery packs. If you're feeling courageous, there's more things you can do if you can somehow pull apart the cells (dangerous!)

"Trickle charging is actually the best way to charge it and improve battery life. The slower you charge a battery, the better. That said, if the charger software is incorrectly designed, it COULD overcharge and damage the battery. For instance, if the upper cut off voltage is 4.0V and the charger puts it at 4.2V, yes, damage will occur."

When it comes to things like cell phone batteries is the myth true that if you let it die all the way, then recharge it to 100%, the battery retains that "memory" and lasts longer? Or is it a bunch of BS so I can just come home and plug my phone in instead of waiting for it to die?

Lithium ion batteries don't have memory.