Let's say you have a li-ion pack that's measuring 21 volts hot off the charger. The more current you pull, the more the voltage drops. When you draw power from batteries, the voltage drops. The best example I can give is voltage sag. With all that said, it it completely reasonable to believe that these new purpose built batteries will be able to outperform the previous generation of batteries in the metrics that are important to tool users. To that end, these cells have likely been created specifically by Dewalt for use in tool batteries which means Dewalt could also spec the chemistry to best suit the needs of power tools. These new cells are lithium polymer cells which use dry solid electrolyte instead of a liquid electrolyte, which allows them to take different shapes than the typical dimensional cylinders. Also, to date, we've been using existing cell formats (18650, 21700 etc.) and just creating packs based on stacks of these cells. Choosing different Chemistries will indeed yield different performance charastice. Meanwhile Lithium Iron Phosphate cells can recharge more times before their capacity is degraded.Ĭreating power tool batteries has always been about balancing the best size, weight, capacity, power delivery, recharge rate and life span. The latter have higher allowable discharge rates so you can draw higher current from a smaller battery (and safely charge them faster). The former have higher energy densities, so you get more capacity for a given size. Within the typical moniker "Lithium Ion" are (for example) lithium cobolt oxide and lithium manganese. Even if you completely discharged and charged the battery up every day, it'd take 1.5 years to wear it down to the 70% point.Ĭommercial use might be a different story though.Ĭlick to expand.Different battery chemistries have different characteristics. I still have 10 year old Makita 18v batteries still trucking along just fine. I think the average homeowner would be hard-pressed to hit 500 charge/discharge cycles on a lithium power tool battery, especially if they have like 3 or 4 batteries. I have seen batteries completely fail (or hold only seconds of charge), but that's not what this number refers to.
However, I have personally never worn out a lithium ion tool battery to the point where I've noticed diminished capacity. Tool manufacturers typically define "End-of-Life" for a battery when it has 70% of its nameplate capacity left - typically after around 500 complete charge/discharge cycles.but realistically, how many of us have ever worn a lithium battery down to this point from normal use? The old NiCad/NiMH batteries - sure. Click to expand.This number refers to the number of complete discharge/charge cycles.
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