Archived from the Tools In Action forum (Dewalt). This thread is read-only.
lets say you have a 20v(18v) saw with a 4.0ah battery and a 36v saw with a 2.0ah battery. would they have the same runtime? any voltage experts?
The 36v would run out sooner imagine amp hours as your fuel tank. You have twice as much energy in the 18v 4.0 ah pack.
Since dewalts 20V batteries are actually only 18V. The two batteries would contain the same energy but it is output differently and the tools will have a different efficiency. The 36V (dewalt will call it 40V) will likely use the energy faster for a more powerful tool which may result in fewer cuts per charge although they would be faster. It all depends on the tool but they do contain the same power
Both batteries have thesame capacity. 72 watthours of power.
18v x 4.0 amps is 72 watt hours.
36v x 2.0 amps is also 72 watt hours.
Now…. It all depends on the tool they are used in.
A 36 volt Rotary Hammer will be more powerfull then the 18v Rotary Hammer and this also use up more power.
So if you compare a 36v Rotary with a 2.0 amp battery —-> 18v Rotary with 4.0 amp the 18 should in theory go longer. ( although the 36v Rotary will work faster because the 36v motor provides more power)
The exception: i do not know if dewalt had this but Bosch has a ‘ compact 36v Rotary ‘.
This is actually their 18v Rotary but then adapted to take a 36v battery.in this example the motor in the tool only needs/ draws thesame current as an 18 volt tool. Meaning it will work as long( and as powerfull) with a 36v/2amp as bosch’s 18v Rotary with a 18v/4.0 amp.
Hope you understand me 😀
True what they said over, but a little note about efficiency:
When you make your cuts, the load will alter the efficiency of your motor.
To low load and the efficiency falls, but a load that pushes the motor way to hard (for example by pushing the saw to hard, or use it on a to thick piece of wood) is just as bad.
A 36V saw will inherently have a bit higher electric efficiency becouse of lower amperage that gives lower electrical losses and heat. But it also usually has a bigger motor/blade. Which in turn will need a higher load to be efficient, since it got more mass to spinn, bigger blade etc…
What I’m trying to say, if the Wh rating on the batteries is the same, it will probably come down to what you are trying to cut. If you cut thin softwood plates, the 18V (“20 V”) unit will probably win. If it’s to cut larger pieces of lumber or thicker plates, or hardwood, the 36V machine will probably be the winner in runtime.
But again, the Wh is usually higher on 36V tools, and in that case, it will probably win either way.
some of the 36 volt tools i believe just step down the voltage to 18v. like the 36v jigsaw or flashlight for example. in that scenario then, either battery would last the same amount of time i assume…
Correct 🙂
Dewalt 36V is being discontinued at the end of the year, just a heads up in case anyone missed it.
Gatorb888 wrote:
Dewalt 36V is being discontinued at the end of the year, just a heads up in case anyone missed it.
what? world wide or US only?
well then i hope dewalt at least comes out with a new 20v 7-1/4 circular saw. preferably brushless. because the 36 volt saw rocks.
Besides the rotary hammer and new batteries there weren’t any updates for some years now. So not really a surprise.
Perhaps a transition to 40V Max?
Gatorb888 wrote:
Dewalt 36V is being discontinued at the end of the year, just a heads up in case anyone missed it.
I’m kinda surprised and not kinda surprised about that. I know they put out some updated batteries the past year or so.
the rotary was updated, but its based on the 20v version.
the newer battery(dcb361 2.0ah) is just a new plastic shell for the most part.
the older dc9360 batteries have used 3 different cells over the years. the original came with A123 cells, then went to samsung cells, then sanyo cells. the sanyo cells have almost double the amp hours of the samsung, so dewalt only put have the number of cells inside the battery, with the rest of the case having false filler cells. thats why the newer battery feels lighter.
dewalt did come out with a more powerful battery (dcb360 4.0ah), by filling the whole battery shell with cells, but this battery seems to only be available in europe.
the original A123 cells
[External image (i.imgur.com), not copied]
samsung cells
[External image (i.imgur.com), not copied]
latest sanyo cells(red). the black are just plastic fillers
[External image (i.imgur.com), not copied]
dc9360
[External image (i.imgur.com), not copied]
dcb361
[External image (i.imgur.com), not copied]
dcb360
[External image (i.imgur.com), not copied]
Gatorb888 wrote:
Dewalt 36V is being discontinued at the end of the year, just a heads up in case anyone missed it.
Glad that I started investing in the new 40V line then. And now I’ve got all those extra batteries with rebates from the garden tools.