Volts != more power

Here’s what I’m seeing in the FlexVolt tool post replies:

  • its the same on paper when you raise volts and lower amperage vs. lower volts and raise amperage.

  • the higher voltage allows more power hungry tools to operate with less heat buildup in the battery pack, wiring, and motor

  • real world issue/cost is in the wiring size, shielding, overall heat buildup , battery efficiency/life reduced due to heat

What I would like to know is why I keep hearing this about table saws:
A 220v table saw is better than a 120v for powering through wood.

Is it because the sudden change in current draw when it hits a tough load not as efficient as already having the steady voltage on hand?


*yes I reworded this so it was less wordy and more to the point/facts. Dragnet reminded me.

Greater current flow = greater energy losses due to internal resistance and heat. Greater voltage = greater energy efficiency.

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And it is not linear - for Direct Current (e.g. battery-supplied power) - losses are the square of the current times resistance

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I thought this was pretty funny.

Metabo North America posted it to their instagram the day of Dewalt’s announcement.

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Hey Stuart can we replace the “like” button with a hammer instead of a heart? What do you think?

To say we appreciate the site usually goes without saying but hopefully you understand how much we appreciate and how much fun we have reading through this stuff and talking about it.

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Milwaukee made a post saying how their 9.0 ah battery was better than dewalt too. They got all defensive right away lol

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What’s the formula for alternating current then? My guess is DC is more efficient.

I think I’ve been seeing a move (back?) to DC for ceiling fans lately and that’s what they’ve been claiming?

Sorry to bump an old post

Yes this is very true but are missing two more very huge components and that is wire size and distance. The distance in wiring from cells to motor is very very short. As current and distance increase you can compensate by increasing wire size. If anyone has taken apart a high powered battery tool like an Angle Grinder the wires are not very big.

Dewalts 60v is just barely a marketing ploy to get people to think bigger is better, just like 20v MAX really being 18v. The battery pack is still a 15 cell pack just like Milwaukees 9.0AH, just arranged in a different pattern. Makitas 36v range is a good example of the very little difference between a 36v Circ Saw and the Milwaukee M18, sure Makitas runs longer but it has 2 batteries. Makita and Dewalts OPE is very similar in performance of 56v and 80v competitors.

I’m not trying to bash this new system and i think it is great that we are getting these new 15 cell packs to power some high demand tools that old 10 cell high capacity packs struggle with. Also the dual voltage so you can use it with old 20v platform is amazing but to call one superior just because it has higher voltage is very miss leading.

Power, voltage, and current are calculated the same in both DC and AC. The trick is that you typically use the RMS value of an AC voltage to substitute for the DC voltage. The power delivered formula is voltage (DC or AC RMS) x current. The entire AC waveform peaks at 170 on the positive side to 170 volts on the negative side, so an entire cycle of AC is actually 340 volts peak to peak. Through the various voltage formulas (derived from calculus), the RMS or work value of the AC is 120. So if you have 20 VDC and pull 1 amp, you can deliver 20 watts of power. If you have 120 VAC and pull an amp, you can deliver 120 watts. The early fight over power distribution was between Edisons DC and Westinghouse AC. AC won for various reasons, but its ability to be delivered cheaply and efficiently over great distances was the primary one.
So think of electricity as being similar to water. Volts is directly compared to water pressure. You can have volts and pressure without any work being done, only the potential for work. But once water flow and current begin, you can now accomplish work but only as much work as you have water or current. So the voltage wars among the cordless folks is mostly an academic exercise for now, but there are caveats which put the devil in the details. Going back to the power formulas (power = voltage x current), if you have a 50 VDC battery that can deliver 4 amps over an hour, you can do 200 watts of work before the battery gives out. If you have a 20 VDC battery that delivers the same current, you can only do 80 watts of work over the same period. But now we really dig into the weeds because the motor efficiency and design along with the power train become as important. Sheesh. Don’t get me started…Now we’re into the realm of DC and AC motor design along with the gear train to figure out definitively whose drills are more powerful and can deliver power from their battery the longest. A more telling comparison might be the horsepower delivered to the chuck and how long that HP can be delivered. The second way is to read the fine ToolGuyd reviews and make your personal choice based on your needs.
The reason your ceiling fans are going back to DC motors is that they are much simpler to control the speed of using out of the box DC converters (no specialty devices). This also allows them to better acclimate to smart-home technology. And similar to the trend to brushless motors in cordless power equipment, brushless DC fan motors are more powerful and quieter to run with little to wear out except the bearing. Since in general, less heat is produced by working brushless motors, even the bearings should have an increased life span. And of course AC motors have brushes which not only cause RFI, but wear out causing more wasted heat to be generated as the motor operates.

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Excellent explanation while still keeping it to a level that most people can easily understand.