It was pointed out to me that Milwaukee tools has sued numerious different tool vendors for building replacement bateries for their tool line,

This to me is deplorable, and would impact my purchasing decisions but I'm not sure I understand this right. I can very easily find knock-off batteries on Amazon,

What elements of the lawsuit was Snap-on guilty of? Are you allowed to make replacement batteries for Milwaukee devices or not?

  • It may not be worth it to go after some no name Chinese knock off brand, but snap-on is a big name company with the ability to pay...
    – Ron Beyer
    Aug 4, 2021 at 5:00

1 Answer 1


The laws are - in the US you can’t make, sell, offer for sale etc. anything that infringes a claim in an issued valid, un-expired US patent. There is no special case for replacement battery packs like there is for medical procedures.

One of their battery pack patents in the suit. US7999510B2, is very broad.

The first claim, below, only requires a housing, lithium ion chemistry and a particular range of current at 18 volts.

It would seem to apply to batteries compatible with other brands of tools. From google patents it seems that the examiner considered 155 previous patents before deciding this was novel and not obvious. Reading the judgement the issue at court was not the inventiveness but wether or not a Canadian company who brought the concept to them initially should be considered the inventor. It was ruled that the Canadian one did not reliably put out the needed current.

It expires in 2023.

Claim 1

  1. A battery pack for powering a hand held power tool, the battery pack comprising: a housing connectable to and supportable by the hand held power tool; and a plurality of battery cells supported by the housing, the battery cells being capable of producing an average discharge current greater than or equal to approximately 20 amps, the battery cells having a lithium-based chemistry, the battery cells having a combined nominal voltage of at least approximately 18 volts.
  • 1
    how is the concept of a battery pack for a power tool patentable to begin with? And why can they include specific numbers in the patent? If battery packs at say 12 volts and 15 amps existed prior, surely expanding it to 18 volts and 20 amps is not inventive in the slightest.
    – user253751
    Aug 4, 2021 at 10:40
  • 1
    It’s easy to imagine inventions relating to battery packs. I also do not understand what made that particular claim non-obvious in 2002 when it was filed. There is nothing odd about claims with numbers. They have two other US patents that may have been involved in the suit. To understand what made the claims allowable one would look up the history of the patent prosecution in Public PAIR at the USPTO. It will show all the office actions and applicant responses during the examination process. I’m on my phone and on vacation so I’m not going to do that for a few days. Aug 4, 2021 at 15:05

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