My son says with an adapter that DW makes you can. He has lots of DW cordless tools he uses at work.

 

@honestjohn,
John, it is the other way around. The 18 volt tools used NiCad batteries, the 20V are Lithium ion. De Walt’s adapter allows a 20V Li-ion battery to be used in an 18 V tool.
At least, that is how mine works.

 

John, your question got my curiosity up so I did some googling...

I was able to find an adapter to use a 20V battery in the 18V tools but not the other way...even though some of the narrative would indicate otherwise.

I did find an article that explains that the 20V tools are actually 18V anyway...seems to make sense considering 3V cells are used to make up the battery (3.6V actually). It also went on to say the 20V goes down to 18V when the tool is loaded and points out the asterisk next to the "20V" on the package (and the fine print).

So technically, from a voltage point of view, the 18V can drive the 20V tool but I'm guessing it's a hardware issue...doesn't fit.

Dewalt does make an adapter that goes the other way...20V battery, 18V tool (you might need the associated charger kit)...you probably already found the same thing. If you haven't, let me know and I'll conjure up the links for you... I did a google "can I use Dewalt 18V battery in 20V tool"...

 

I did that too. The adapter might be the way to go and just get him the 20v tools with the adapter so he can use his old ones too.

 

I have the adapter, 20 v to 18 v only. My adapter is very difficult to remove from a tool. I think I'd like to have an adapter for each tool, but I have 3 drills, the circ saw, sawsall and jig saw. That's five adapters. My hands aren't as strong as they used to be, so maybe the stiff release buttons will be easier for others. I can use a pair of giant channel locks to press in the release tabs, If that's the norm, I hope DeWalt will reengineer that release, it's the only fly in their ointment.

The new batteries are really expensive, but they run for a long time before discharging. You also have to buy a different charger. You pull the 20 v off the adapter to charge it (easy) and you can't charge it in the old charger. At least DeWalt isn't leaving you out in the cold. You can buy off-brand batteries in both sizes, but they don't last all that long and have a high failure rate. I really love that circ saw and the jig saw. Not wrestling with a power cord is nice, and DeWalt has a nice selection of blades for the circ saw. Use Bosch blades for the jig saw, much better results.

 

I was told at a trade show about a year ago by a DeWalt rep that the 18 volt system either has or will soon be discontinued. Both the batteries and the motors in the tools are old technology. The new brushless motor tools are pretty sweet, they are lighter, smaller, more powerful, and run a long time on a charge. I have several and my only complaint is the cost. Then again, if I look at what Festool costs they seem almost inexpensive!

 

I purchased this adapter 2 years ago. It works great except it is near impossible to remove from the tool. I leave it on my one main drill. Thinking of purchasing another. At the time and mine does the same - you must remove the battery after use, or the battery will be drained dead in the morning. An extra step which I often forget. Not sure if they fixed the problem. I have seen reviews where people have filed away at the latches where they clamp onto the tool, making it easier to take off - I may do so. I haven't taken it off since I put it on the drill. The price of the 18v batteries have gone up and are around the same price as the 20v batteries, making the purchase of the adapter more appealing.

 

NickP, I've read the same thing. The use of the "20 Volt" is an advertising thing. Other manufactures with the same battery setup call their tools 18Volt.

 

Yup...just like the 12V batteries in our vehicles...as soon as they are fully charged they read 13.xV... at all the other times, it will read 12.5-.7...

 

Ron, hadn't thought of filing down the latch. I think you'd want to remove a bit from the bottom of the latch, not the angled top part. I'm going to give it a try. If I can keep using the 18v tools by doing that, I'll be happy. If it doesn't help, I'll replace what I can with Bosch tools. It really pisses me off to think of having to junk about $700 worth of perfectly good tools. Last 18v battery I got free. It fell off someone's truck and was laying in the street.

The other option is to go to a battery store and have the 18v batteries rebuilt with new cells. Did that with a Makita but made the mistake of approving a slightly undesized cell because they didn't have the right ones on hand.

Anybody here had success having batteries rebuilt?