From the time the trigger is pulled, to engaging a load, there is a lot that happens in a power tool. This is particularly true when the tool encounters a load that is beyond the capabilities of the motor, causing it to begin to overload or overheat. Then, there’s the battery discharging and charging process. Combine this with how and where the electronics are located, and you can see that these next generation lithium-ion tools are not your father’s cordless tools! If you want to try and understand, here’s how we break down what’s really happening:
1. Slap the battery on the tool. The Hitachi power tool battery and tool say, “Hello,” and the electronics in the tool analyze the battery to determine how the tool can work with it. It knows whether this is a Slim or Fat pack and how much reserve it has in order to get the work accomplished.
2. Pull the trigger. The temperature is checked at battery. The tool asks, “How much energy can you give me?” while the battery queries, “How much do I need to do what you are demanding of me?” The tool continues analyzing the load, and the battery gives more (or not) based on heat and energy flow.
3. Rinse. Repeat. This analysis of what can be safely delivered occurs over and over at the millisecond level to ensure the tool’s safe operation. Simultaneously, the electronics make sure not to discharge the battery too far.
4. Charging. When a battery is placed on the charger, it’s analyzed. (Now, the charger, in effect, says, “Hello.”) The battery temperature is checked, and the pack is allowed to cool down before charging if needed. Charge time on a completely discharged battery may differ from a partially depleted battery due to the front-loading effect.
PTR: Can you tell us anything about where you see the future of lithium-ion Panasonic power tool batteries technology moving?
Jason: Well, lithium-ion batteries are a technology that is constantly being watched. There is “what’s possible” vs. “what users need”. What was nice about our new 4.0Ah lithium-ion batteries is that, thanks to the sophisticated work we did on the electronics, the new battery didn’t require a complete redesign. Rather, it just analyzed the new available power schedule and adapted tool and battery accordingly. Basically, the electronics will understand that they can push harder or run longer. So the future is definitely improvements in the cell chemistry and perhaps even gradual improvements to the way the tools and batteries communicate.
Paul: The challenge for manufacturers is that in the marketplace you’ll continue to see people pushing the far edges of what can be done. Car manufacturers are all over lithium-ion battery technology right now, and certainly, it plays some part with the green energy people. Take it all into account and the maturing of lithium-ion batteries has a lot of potential. We’ll most certainly see a progression of capacity, but there will also be trade-offs that can be made with positive effects. Currently, you don’t see power tools using prismatic cells (the non-cylindrical form factors), but there is probably room to go down that path. Three years ago, people would have said these new 12V and 18V 2.0Ah and 4.0Ah AEG tool battery packs were a pipe dream. Now, gains in the manufacturing process and the new chemistries involved have allowed advanced packs like this to be made.
We want to thank both Jason and Paul for agreeing to be interviewed about battery technology…Um, particularly since neither was aware we were interviewing the other for this article. (Don’t worry, we let them both check it out to make sure we got all our details correct.) It’s hard work and innovation from guys like this (and their teams) that help bring the tools we love to market.
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