Over the years, I've had a number of portable devices that use batteries. They ranged from ordinary alkakine cells, through Ni-Cads, Ni-MH cells, and Lithium-Ions. The latter are probably the best, but more expensive.

I had a cordless phone that used Ni-Cads. Mindful of the possible "memory" issues with Ni-Cads, I used to let it charge overnight, and then when I'd take it off the base in the morning, I'd keep it off for a couple of days to make sure it disharged a lot and then put it back on the base/charger. Not sure it did any good, bit I seem to recall reading that Ni-Cads shouldn't be on a trickle charger all the time.

I replaced that phone with a newer one, and this one uses Ni-MH batteries. These are supposed to be better than Ni-Cads, at least regarding "memory". My daughter has one with the same battery pack, and she leaves it on the base/charger all the time. Been running for a couple of years with no problems.

Is this proper protocol for Ni-MH batteries? Is it harmful if you let them run down before charging?

As far as Lithium-ion batteries go, I have them in my laptops and cameras. For the laptops, they can be connected to the charger all day long with no apparent ill effects, and the ones in the camera are just run until they indicate they are low, and then I stick them on the charger.

While my methods have been successful, I've found information on the 'net that is confusing, to say the least. I was wondering of any of the gurus here have definitive information on the subject. After all, pretty much all of us use cell/smart phones and laptops, so I would think it would be of interest.

Ni-Cad batteries developed a memory and needed to be drained most or all of the way before charging.

Li-ion batteries actually work best when not allowed to be drained most of the way: better to charge them after a shorter use period.

Ni-MH batteries are somewhere in between...they have fewer memory issues than Ni-Cad batteries but need to be periodically drained and charged from flat.

Going back to the days when Ni-Cad batteries were used in almost all applications, yes they did develop a memory and would have to be discharged and then recharged.

The problem with using the electronic device to discharge the battery is that the device had system protection to prevent damage from low battery voltage and shut down before the batteries were fully discharged so the batteries never fully discharged eliminating the memory problem.

I bought a device that totally would discharge the Ni-Cads down to zero, then slowly recharge them and I found that my devices, first it was a Sony Walkman and later a Sony CD portable player would last much longer in service after doing what is called a deep cycle on the Ni-Cads.

Today Ni-Cads have been replaced mostly with Li-ion batteries, which have a lot more power for their small size and do not have the memory issues that Ni-Cads did.

Ni-Cad batteries are still used in all large airplanes today, even new designs except the B-787, these batteries have to be removed, deep cycled and serviced every few months to maintain their efficiency.

Mr. Elliott

Hello, my name is lensman and I am a rechargeable battery nut.

My main NiMH battery charger is a PowerEx MH-C9000 charger/analyzer. It has five modes of which I mainly use the following ones:
1. For new NiMH batteries that are not the low-self-discharge type, I use the Break-In mode. This applies trickles a "forming" charge but takes 2 days. Here is a thread in another forum that talks about the pros and cons.
2. Otherwise I mostly use the "Charge" function, which recharges batteries. This particular charger lets you pick the charging current. The experts recommend that you charge your NiMH batteries at 0.5C-1.0C. For your standard 2000mAh NiMH AA cells, that is 1A to 2A. For 800mAh AAA's, that's 400mA-800mA.
3. I will occasionally send my batteries through a "Refresh/Analyze" cycle. This refreshes the battery by deep cycling it in 3 complete charge-discharge cycles. The MH-C9000 will also display the capacity of your battery at the end of the refresh.

As an FYI, the MH-C9000 is the current gold standard for consumer-level battery chargers. It has four independent bays so you can charge one cell while refreshing another and doing a break-in on another, etc. You should be able to find one online for about $60.

Lithium ion batteries are actually fairly finicky and if it weren't the case that manufacturers were mandated to use charging and discharging control circuits on them I am sure that there would be hundreds if not thousands of battery charging "incidents" in the home. The best thing to do if you want to read up on it is to Google for Lithium ion battery charging FAQs on either RC forums or, in my case, various flashlight forums. But what gfunkdave says is correct. Li-ions don't like being deep discharged. Oddly enough, they like being stored at 40% charge. Actually, one key thing about Li-ion batteries is don't let them discharge below 2V. This means that you should recharge your camera or laptop battery periodically while it is in storage.

Get yourself a good battery charger from Thomas Distributing and stop worrying about it. You can leave the batteries in the better smart chargers all the time and not worry about them. They also support conditioning.

http://www.thomasdistributing.com/AA...ers_c_644.html

The better ones aren't cheap, but IMO, they are worth it. I have 2 of the Maha 8 battery smart chargers for my AA and AAA's.

-David

I don't worry about it.

When the performance becomes unacceptable, I just throw it away (uh ... 'dispose of it in an ecologicaly-friendly fashion') and get another device or another battery. Life is too short to fret over something like battery life, unless it's your profession (or, in lensman's case, obsession).

I just wanted some guidelines so I wouldn't do too much stupid and get a reasonable life out of these things.

Those Maha chargers help with that too.

-David

I would like to heartily recommend the Maha PowerEx MH-C9000.

Actually, maybe buying one is not so good of an idea. I think my obsession really did start when I got mine...