By David Rosner
Tesla’s doing it, cell phones became viable with it, and now Goal Zero’s Yeti has gone the way of the lithium battery. It’s expensive, seems to catch fire sometimes, and can you throw it away in a regular trashcan when it’s time? Well don’t do that, much like larger lead acid batteries, you need to dispose of these properly, not in your standard recycling, but taken to a certified facility.
As a battery company, Goal Zero has investigated and produced products using multiple battery technologies. We have seen both successes and failures within the emerging market of portable power, but most importantly, we have learned a lot in doing so. Many are wondering what the main differences between lead acid and lithium technologies are, and why the whole world is currently moving in the lithium direction.
First and foremost, we must talk price. No longer an exotic futuristic technology that costs an arm and a leg, lithium has arrived in the realm of attainable, available, and affordable. The future is now, and the price of lithium has dropped dramatically in recent years. Lithium is closing the gap in price per watt compared to Lead Acid, especially when factoring in # of cycles and depth of discharge. This allows the other benefits of lithium to exude a much greater value proposition.
Secondly, plain and simple, smaller + lighter= better. Compared to its lead predecessor, lithium is up to 2/3 lighter, while giving the same amount of power (energy density). This allows a better user experience simply from a labor standpoint. The smaller form factor allows for a versatile use case with convenient portability to get more power to more places and more devices.
A deeper depth of discharge enhances user experience. Lithium can be discharged further before harming the battery, essentially increasing its potential power output and overall life. Because lithium holds a steady voltage, it can deliver 99% of its stored power! Lead acid’s continuously dropping voltage sees product functionality issues as voltage gets lower, leaving a little “gas in the tank” so to speak. Also, lithium operates in a much larger temperature window. Safety goes up because of this, where we only see failure in extreme thermal conditions that simply exist less in the real world. However, when lithium exceeds its limits, it fully shuts down… or catches fire, whereas most of the time lead acid will function, just with less capacity. All in all, lithium is more reliable as a byproduct.
As far as lifetime, lead acid and lithium don’t have a huge difference. Only LFP, lithium iron phosphate, has a reliably significant increase in the number of cycles it can handle. Oddly, most devices are not using this technology, opting for the smaller size of other lithium technologies over the larger, heavier LFPs. Otherwise, heavy use sees only a few hundred cycles in non-LFP lithium cells, which can scale up to a few thousand with much lighter cycling (depth of discharge), just like lead-acids. Either way, you will get many years of good use out of your battery before needing to consider a replacement, so its perceived value over time is present nonetheless. As a bonus, the idle shelf life of lithium is significantly better (it can sit longer unused until the battery self-depletes). This just means that a lithium battery will probably still work if it has been sitting in your garage all winter, once again increasing value and lifetime.
The few drawbacks found in the lithium world are getting smaller. Lithium prices have dropped significantly over the past few years, but still remains more expensive than lead acid. Chaining multiple lithium batteries isn’t as easy as lead acid and is a hurdle currently being overcome, no big deal. We are also beginning to see lithium batteries becoming replaceable, so you don’t always have to throw away your device when the battery dies. Finally, the international availability of replacement batteries is still dominated by lead acid. As Goal Zero prides itself on humanitarian work around the world, this cutting edge technology remains rare in the dark corners of the planet. Now, a lead acid product can live longer around the world only because lead acid batteries are readily available. Otherwise, there aren’t many reasons not to go the way of the lithium battery.
From a safety standpoint, the world has learned to use lithium properly… mostly. As with any learning curve, we must find out the bad in order to prevent it. The knowledge and safety protocols available within this sector are growing every day. Now we can limit most harmful issues, so besides dealing with TSA and UPS, the hassles of lithium are largely over.
The impact of our obsession with lithium is changing the way we look at power. From pocket batteries to micro grid community backup, lithium is working its way into our lives on multiple fronts. We should no longer be wary of this emerging technology. Smaller, lighter, and more powerful are the way of the NOW. Enjoy the new power revolution!