Internal resistance at room temperature isn’t very important here, it’s the internal resistance and operating temperatures under load that essentially determine how much work is done per Watt-hour of energy storage before the low-voltage cutoff is reached. It mainly comes down to internal resistance and battery pack design. Li-ion batteries within cordless power tool battery packs are balanced, specifically to avoid the type of circumstances you describe.Īnyway these are all ideas trying to explain their 50% more work but not 50% more capacity logic. If thermal dissipation is impeded due to the number of cells, that could change things. This isn’t universally true, hence my mention of complex cooling considerations. Double the energy losses from double the amount of stored energy means that efficiency is independent of the number of cells. Yes, the total energy loss from 2 cells will be higher, but you’re also starting with double the energy storage. More cells isn’t another “inefficiency factor.” If say there are 10% energy losses through heat, doubling the cells doesn’t change that number. I misunderstood you to be saying a 5-cell 5Ah battery would be more efficient than a 10-cell 5Ah battery merely because of the fewer number of cells, which would be completely inaccurate. The rest could still hold charge that was accounted for but you don’t have access to.Įxcept for there are complex cooling consideration, energy losses should be proportional. The cells all have different internal resistances so usually only 1 has to be 100% “depleted”. I just mentioned it as another inefficiency factor. This isn’t related to the number of cells, but the physical and electrochemical properties of each battery cell, and yes the power draw.Īll things being equal, in term of absolute numbers 2 cells will waste twice what 1 cell will. The main energy loss is in the form of heat. Yes, you get a voltage drop, dependent on the internal resistance. It comes down to current draw and internal resistance, which is temperature-dependent. As soon as you have a load you get a voltage drop. The efficiency of converting the stored energy into electricity is dependent on the load.
It seems to pick up perfectly where the 1.7Ah battery leaves off. The PowerStack 5Ah battery, on the other hand, performed well with any and every 20V Max cordless power tool I tested it with.
What I have found is that the compact PowerStack battery is a great substitute for traditional cylindrical cell compact batteries, and even higher capacity batteries where I need higher power delivery but not necessarily the longer runtime. In theory, I might still use cylindrical cell 8Ah batteries for longer runtime, but in practice I tend to reach for FlexVolt 9Ah batteries for more demanding and longer power-draining tasks. Do I want a more compact and lighter battery? Or would the tool or task benefit more from higher power and longer runtime?įor my uses, these two battery sizes could replace all of my 20V Max cylindrical cell cordless power tool batteries from 1.3Ah to 8Ah. However, the difference really comes down to intent. I sought out thinking there would be tools and tasks clearly matched to the PowerStack compact 1.7Ah battery, and others that are better matched to the PowerStack 5Ah battery. While both PowerStack batteries, 1.7Ah and 5Ah, are engineered with 5x Li-ion pouch cells, the 5Ah battery is going to be capable of greater power delivery than the 1.7Ah battery.īased on my testing so far, the PowerStack 5Ah battery is the ideal match for heavier duty tools, such as angle grinders, larger rotary hammers, 7-1/4″ circular saws, blowers, and other tools where runtime or power are the priority. The PowerStack 5Ah battery can deliver longer runtime compared to the 1.7Ah battery.Įven though the PowerStack 1.7Ah battery is 50% more powerful than the compact 2.0Ah battery (DCB203), the PowerStack 5Ah battery can deliver 50% more power compared to the 5Ah battery (DCB205).Īs the DCB205 battery is engineered with 10x 18650 Li-ion cells, it is capable of greater power deliver than the DCB203 battery, which is engineered with 5x 18650 cells.
I added a single PowerStack 5Ah battery into my kit, and found that it works well with all 20V Max cordless power tools. It serves well for quick tasks, and prolonged use in lighter duty or more compact tools. I have used the PowerStack 1.7Ah battery with compact drills, impact drivers, impact wrenches, Atomic-series circular and reciprocating saws, and also woodworking-focused tools such as the brushless sander and router.
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