Cordless Reciprocating Saws - Part 2

Understand 18-volt battery technology and alternative power supplies.Subject:  Cordless Reciprocating Saws, Part 2Topic:  Power supply for cordless reciprocationg sawsObjective:  Understand 18-volt battery technology and alternative power...

Battery Management For Best Performance

We mentioned earlier that reciprocating saw 18-volt batteries, unlike other NiCads you are accustomed to, do not develop a memory. Our testing over almost two years has proven this to be true. Another myth that must be put to rest is that “getting the last drop of juice” out of the battery is a good thing to do.

Fire officers and rescue instructors may claim that running a battery until it is completely exhausted and the saw stops operation is the only way to get the full power from the battery. For an 18-volt battery, completely draining it can permanently damage it.

An 18-volt rechargeable battery should be removed from the saw as soon as it slows and fails to produce sufficient power for the cutting job. Do not continue to run a battery until it is completely drained. Pushing it beyond the point of its useful work will permanently damage the battery by causing the internal cells to reverse their polarity. The damaged cells will not accept a charge, significantly weakening the battery.

As soon as the saw slows significantly, consider the battery spent. Remove it and place it on a charger. Also contrary to popular fire service belief, you can and should charge a partially discharged battery pack at any time with no adverse effect on the battery. It will not develop a memory like the pager and portable radio batteries to which we have become so accustomed.

Ron Moore, a Firehouse contributing editor, is a battalion chief and the training officer for the McKinney, TX, Fire Department. He also authors a monthly online article in the “MembersZone” and serves as the Forum Moderator for the extrication section of the website. Moore can be contacted directly at

Series Links: Part 1 | Part 2 | Part 3 | Part 4 | Part 5