Is there a future for 28V Dewalt tools?

[Mark Burnette]

Now that Dewalt has discontinued the entire 28V lineup I'm not inclined to further invest in the platform. Especially since I also have several 20V tools & that battery looks to have support well into the future. I hope!

So how can I adapt my 28V saw to use my 20V batteries? I wrote Dewalt asking this question and I hope it leads to an adapter plate but I won't hold my breath.

Has anyone found a solution to adapting the 28V tools to the 20V platform? I'd prefer not to have some Red Green duct-taped disaster but I'm considering that, too :)

[Rod Sheridan]

Mark, you'll need to simply have the battery packs rebuilt as they wear out. As long as you don't smash the battery pack so that the housing is unusable, you can go on indefinetely by rebuilding the battery packs..

A 28 volt motor isn't going to develop full power with a 20 volt battery.........Rod.

[Mark Burnette]

I want to commonize on the 20V platform. I'm not likely to notice any real difference between the 28V 2.4AH pack vs the 20V 3.0AH pack except maybe a little lower rpm. I can easily live with this rather than support additional chargers & packs.

[Julie Moriarty]

The problem could be the motor. It was designed to run on 28 volts. You're talking about a reduction of almost 30% in voltage. In the world of electricity, that's huge. I've seen motors burn out from a lot less voltage drop than that. But that's in the AC world. I'm not sure if the same rules apply in the DC world but I'd wait for a reply from DeWalt before putting the 20V batteries in. BTW, the amp hours (AH) have nothing to do with voltage. So a 20V 3.0AH battery won't run your 28V tool any better than a 1.5AH battery will. It will just last longer between charges.

[David Malicky]

If it's a standard DC motor (~quiet), then RPM is linearly proportional to volts. So a 28V rated motor run at 20V would run at 71% speed. If it's a universal motor (loud), RPM is also proportional to volts, although I'm not sure it's linear. Generally, those motors will happily run at the lower voltage and speed (similar to pulling the trigger part-way), unlike AC induction motors which would indeed draw more amps and overheat.

[Greg R Bradley]

You will have more problem than you think.

The Dewalt 28v tools actually are 28 volts, to be precise they are actually 28.8 volts.

The 20v tools are the same outrageous lie that caused the original 10.8v LiIon tools to now be called 12 volts. They are actually 18 volt tools.

You can start to realize how crazy it would be to run a 28.8 volt tool on 18 volts.

Your solution is to have battery packs rebuilt until the tools are no longer worth rebuilding.


To make it more clear:

LiIon tools are: 3.6, 7.2, 10.8, 14.4, 18, 21.6, 28.8, and 36 volts.

25.2 and 32.4 are possible but do not exist in tools to the best of my knowledge.

[Mark Burnette]

Oh darn, I wont be able to jog alongside the saw as I rip a 3/4" panel. OK maybe this idea isnt for everyone. I just dont want to throw out running tools because of high cost of replacement batteries like I did with my 12v models.

[Jeff Duncan]

Well there are others who can advise you much better than I can as to the technical aspects of the tools. All I can say is I have on occasion swapped batteries on some of my Makita tools and none were any worse off that I could tell. I didn't do it on a continuous daily basis though, so not sure how it would affect the tools over time???

good luck,
JeffD

[Mark Burnette]

Update.

I was pretty determined to be able to continue to use this $400 saw even though nobody will rebuild the battery packs and Dewalt doesn't make an AC adapter or adapter to use a different battery. What I found was that these 28 & 36V packs have a battery monitor module inside the pack that actually stores charge/discharge cycles, charge state of each cell, and temperature. It's SO smart that any problem at all will disable the pack so it's useless. I found a 36V pack in the recycle bin of a Dewalt service center and they let me take it. Once home I found it had ONE weak cell inside. I bought a 28V "unknown condition" pack off eBay for cheap and found it also had ONE weak cell inside. Both these packs read "Bad Battery" when put on the charger. I removed one good cell from the 36V pack & soldered it into the 28V pack and now it charges fine & the saw will run.

It's just plain stupid that a single weak cell in a battery pack should make the tool inoperative but that's what Dewalt has done in the design of this system. I hope all cordless tools aren't going to be this "smart" in the future!

[Steve Peterson]

I agree that the present solution is not very smart. It is a simple solution to prevent charging or discharging a battery pack with a bad cell. The cells are in series, so all the current that flows through the good cells also has to flow through the bad cells. This causes even more damage to the bad cells and in the case of Li-ion cells can probably make them explode.

The eventual solution may be for manufaturers to install a bypass switch on the bad cell to allow the good cells to continue working. At least you would be able to continue working, although it would only be at partial capacity.

Steve

[Bill White]

At some point we'll have to decide that extreme high voltage battery operated tooling is just not up to the perceived value.
18 v stuff is as big as I own. Past the capabilities of 18 v, I go to corded stuff. I don't want to break an arm with a cordless drill trying to drill a hole thru a railroad tie.
Bill