Ok, first id like to correct a few things that were posted…
Ryobi is not a Home Depot brand. They are actually owned by the same company that ownes the “Milwaukee” brand.

NI-CAD batteries do have a “memory”. But in cases like this its the least of the problems.
There are two reasons that you are having problems (other than using the wrong tool for the job)
The first problem is that the first gen (ni-cad only) charger is charging the cells way to fast. The cells that Ryobi chose to use in the batteries are rated for a 1/4C charge over 5 hours (1/4 cell capacity for 5 hours) Most if not all consumers would find waiting 5 hours for a recharge to be unacceptable. They could have used higher spec batteries… but the the packs would be $60 each insted of $50 for two.
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The second relates to the chosen cells again. This time its the discharge rating. These cells are rated for a 3C discharge rate. This means it is rated to discharge in constant use no faster than 20 min. Or a constant 4 1/2 amp draw for 20 min. There are only 5 tools in the line that pull less than 4 1/2 amps right now. The work light, the staple gun (just barely), the hand held vac, the caulking gun and the new radio/charger (im not counting the old radio as its being phased out).
As you pull more current than rated, you start to loose capasity (the lost energy is generating heat). If you pull a largs enough current the battery will start to get over-heated. This causes even greater loss in capacity, and could lead to total failure of one or more cells. This cant really be avoided other than going with a 10-15% duty cycle.

Also, as someone has already said, Dont store your ni-cads completely discharged. Anything over 70% and you should be fine. Also the 1% a day is a good rule of thumb.

Now for the li-ion packs. They so have some Major advantages… but a few down sides.
The first good thing is the capacity upgrade to 2.4Ah (over the ni-cad’s 1.5 AH). Second is that the li-ion cells maintain the voltage over a longer period of the discharge cycle, unlike ni-cads that start loosing voltage as soon az the current draw starts (starting the power tool).
Also, since the battery pack is current limited and has a built in under voltage shutoff you dont have to worry about hurting the battery by use.
Also due to the charge profile of the li-ion chemistry, they can charge the first 75% of the capacity in 15 min (or less in some cases) as long as the temp is kept under control.
The one down side to li-ion (other than the cost) is that you CAN NOT store them fully charged for an extended ammount of time.
If you dont plan on using your tools for a while, dis-charge them to 50-70% total capacity. This is due to the cathode mesh breaking down.
This is also why your lap-top batteries die so quickly (by leaving them in the computer charging all the time). Yes, li-ion batteries do self-discharge. But it will take over a year for it to discharge from 70% toa point where it is in danger of damage.

One point to remember though is that the current limiting on the li-ion batteries is a blessing and a curse. If you are doing something that requires a LOT of power like driving 1/2″ lag bolts (with the hammer drill). The li-ion ‘s over current protection will kick in. So the way I avoid that problem is keeping 5 li-ion and one Ni-Cad pack (yes, i really do need that many batteries).

One final note ( i dont know if he was kidding or not)… DO NOT store your li-ion or ni-cad (or ni-mh) packs in the fridge! If you do, let them set outside the fridge for at least half a day to allow tbe inner cells to warm back up. Using a very cold rechargeable battery in anything that pulls more than the work light WILL damage them. It could take as little as a few min to completely destroy the battery pack if you go straight from the fridge to the canister vac or the sawz or the trill under heavy load.

On a side note, with the charger that was just released… it IS safe to leave the ni-cad in the charger. That only applies to the 3rd gen chargers (not the ni-cad charger or the first green charger or the 6pack charger)…
It is also compatible with Ni-mh cells). It not only use cell temp, but also current draw too (thats why it is also safe for ni-mh)

I appologize for the grammer and spelling … its now 0300 and im typing this on a cell phone :-(

Unfortunately, whatever you want to call it, it means that the devices run out of juice way too soon to make them useful portable tools when using the NiCd battery packs.

Thanks for the tip on NiMH replacement. I’ll probably just stick to the lithium ion batteries.

It’s not recommended to replace the NiCad cells with NiMH. Not unless you intend to use a charger that is designed to charge the NiMH’s.

Lacrosse(SP) has a few battery chargers for AA and AAA types that run batteries through a conditioning cycle and charges them slowly. It makes a huge difference in how the batteries perform. I wish there was such an animal for my 18V NiCad’s.

The LiIon batteries are great for a few years and simply die off. Think of your cell phone battery how long does it last? Probably roughly 2 or 3 years. Heat including room temperature heat kills these guys off. I suppose you could store your 89 dollar batteries in the fridge and get them to live much longer. Google Battery University for more info.

Meanwhile, any one seen an 18 volt charger that will automatically condition the batteries and do the charging in a slow gentle manner?

The regular jobs, siding a house, building a deck, taking down a tree, framing a garage, etc need real tools with reliable power.