I was looking at battery power tools and their different battery voltages. Some of the voltages are listed twice, with and without "max". An example for mowers is "40-volt" and "40-volt max". What's the difference between the voltages with "max" and without "max"?

battery voltages

  • What brands are you looking at it may have something to do with the style of the battery contacts , I have a 6 ah battery that the contacts look the same as the 2 ah batteries the difference is each cell is larger. – Ed Beal Jul 29 '20 at 17:22
  • What website is this? Most likely those categories are just echoing the text in the advertising blurbs for the products found. It's possible, tho' a bit unlikely that, e.g., a "40 V max" tool would function with a 24-V battery, but my guess is just poor English. – Carl Witthoft Jul 29 '20 at 17:45
  • @CarlWitthoft Lowes. – Ghostship Jul 29 '20 at 18:04
  • This isn't a question about batteries. This is a question about a website's search engine. There are a variety of reasons to allow ranges in search filters. – Harper - Reinstate Monica Jul 29 '20 at 18:42
  • @Harper-ReinstateMonica not sure I agree with you. I pulled up the Lowes site and "20 volt max" yields a set of 7 brands, while the "20 volt" yields a different set of 7 brands. "Max" is all about marketing 'cause "Max" sounds... maxier... – FreeMan Jul 29 '20 at 19:26

There is one brand of "20-volt Max" tools that reasonably clearly state on their packaging something to the effect of:

Battery provides 20 volt maximum starting power. Provides 18-volts in use.

As a matter of fact, they'll sell you a simple physical adapter (and some wiring between the contacts) that will allow you to use the "20-volt max" batteries on their older 18-volt line of tools.


"Max" is 98.475% marketing because "Max" sounds, well, like more than "not-max". (And 99.238% of all statistics on the internet are made up on the spot.)

  • Presumably that "20 V starting" is the rating of their battery, not the tool's draw. – Carl Witthoft Jul 29 '20 at 17:46
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    Yes it is, @CarlWitthoft. I don't remember the exact wording at the moment and can't be bothered to go look at the DeWa... (oops) site right now to get it. :) – FreeMan Jul 29 '20 at 17:47
  • Edited to make it more explicit – FreeMan Jul 29 '20 at 17:47
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    Most assuredly, @GeorgeAnderson – FreeMan Jul 29 '20 at 19:12
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    The "20V" claim is entirely bogus. Li-Ion batteries have a cell voltage of 3.6V nominal which divides evenly into 18V (i.e. 5) but not into 20. So there is no way to get 20V out of a 5S battery pack which these "Max" cells are. It's marketing hype! – jwh20 Jul 29 '20 at 19:30

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