18 volt Battery/Hold charge?

[Rob Mills]

I'm curious as to how long your 18 volt batteries hold a charge just sitting un-used after a full charge. I have a 2 yr old Ryobi drill that is just casually used and the batteries which have never been run low drop to an un-useable low (12 to 15 volts) within a week of being charged. I also have a 8 - 10 year old Ryobi 12 volt drill with original batteries that is still quite hot a month or two after being charged. I'm tying to decide if I should shell out $39 for a new pair of 18 volt batteries or throw in the towel. The 18 volt drill has seen very little use as has the 12 volt drill. RM~

PS, The 18 volt batteries show a reading of over 20 volts just after being charged.

[Mike Berger]

What's the battery technology? Nickel cadmium will stay charged on the shelf a lot longer than nickel metal hydride.

Rob Mills wrote:

[Leon]

All cells will have a surface charge and read a bit higher right after recharging. Run the tool a little bit and the voltage will come down.

That said, I mentioned this to Renata in another post. Keep in mind also that larger voltage batteries have more cells packed inside the battery case and heat is an enemy to these cells. Because there are many more cells in an 18 volt battery vs. a 9.6 or 12 volt battery you have more cells insulating the inner cells during heavy use and recharging. It is an inherent fact that the more cells a battery has and the way they are packaged in the battery pack the shorter life span they will have when compared to the lesser voltage ones. Basically, what you gain in longer run times and power you loose in life expectancy with all things being equal.

[Fred Toewe]

The loss of charge while sitting on the shelf is a very common 'feature' of NiCad's, which those most likely to be. The best NiCad batteries will not have this feature when they are new, but most will develop it with age and/or use and/or abuse.

That said, does it matter? In your use of the tool is it important that it hold the charge for weeks or months, or do you/can you/ simply recharge the tool when you need to use it for more than a short duration?

I have had batteries with this feature and have continued to use them for years. It just doesn't matter to me. Perhaps you also have two batteries and thus can recharge one while using the other as I do. Fred

[Rob Mills]

It doesn't say on the battery but I'm fairly certain they are Ni Cad's, doubt Ryobi could (or would) sell a pair of NMH's for $39. RM~

[Rob Mills]

[Rob Mills]

Doesn't really matter but even in use after charging it doesn't really match my old 12 volt Ryobi in power while using or ability of holding a charge. I can charge that 12 volt one, walk off and leave it, come back 2 months later and it can still get up and go. I wouldn't have even bought the 18 volt one but I loaned the old one to a neighbor and they ran one battery too low and it never would take a charge after that. Thanks for your reply, Guess I was expecting some reliability similar to the old Ryobi. RM~

[Rob Mills]