Well, today I had a great conversation with Mr. Philippe Bouchard of EOS Energy Storage. They make a new Zinc-Air battery. And it is a technology that I have been very excited about. But my excitement has been tempered a bit.
Today I got to confirm a few things. First off is their make up. The US has one of the largest amounts of Zinc of anywhere in the world. So economic advantage and national security, check. There are no heavy metals, and the electrolyte is almost a saline solution. So, your 2-yr old won’t die if some how they managed to take your car apart and started gnawing on it. They also won’t catch on fire if over-charged, over-discharged, crashed, or punctured. So they are safe, check. Next, they are designed to last 10,000 cycles. Long lasting check. They cost $160/kWh, which is about 1/3 of what an A123 will cost you. They are affordable, check. They are capable of 620Wh/L vesrus Lithiums 230Wh/L. So over 2.5 times the energy density, check. The BMS is way simpler than Lithium batteries require to keep from bursting into flames. Simpler and cheaper BMS, check.
So they have 2.5 times the power density, cost 1/3 as much, will not burst into flames, will not harm the environment or yourself in anyway, and strengthens the US economy! Is this a miracle battery!? Unfortunately no. Unlike the Lithium batteries you see in any of the bikes in the race series which have C rates of 15C, this battery has a discharge rate of 1/6C, and is only available in grid applications. Yeah I know, my bubble bursted too. Although, they are in contact with auto manufacturers trying to find a partner to help them develop the auto battery. Trust me I gave him a pretty good de-breifing about elmoto racing. Not as bad, but not that helpful is that the charge rate is 1/6C as well. This means that the battery takes 6 hours to completely charge or discharge at full throttle. Although, Mr. Bouchard did say that they are working on some surge protectors that might allow up to 1/3C. That’s basically like giving a turtle Red Bull. Clearly this has little to no racing application. To try to put in terms of motor power, start with the amount of power you want your motor to have. Lets use Brammo’s new Empulse, and it’s 40kW motor, for example. A 40kW motor at full power could drain a 40kWh pack in 1 hour. That is 1C. So the Empulse’s 40kWh motor could potentially suck it’s 9.31kWh pack in a touch under 14 minutes (do NOT try this at home), or 4.3C. So if you had a 9.31kWh EOS pack in the bike the biggest motor you could run is a 1.6kW (or 2hp). Yep, that’s pretty weak. But, what if we replaced the Empulse’s pack with a physically identically sized pack? Well, we end up with a 25kWh pack, that weighs a bit more than the 9.31kWh lithium pack. That takes the ranges from 121/77/56 miles to 325/206/150 miles! But to keep the stock motor we would need a 1.6C rate, which is 9 times the discharge rate that the technology has now. Basically, the biggest motor you could run is 4.1kW (or 5.6hp). So depressing. However, they are also looking at pairing their Zinc-Air batteries with their Lead-Acid concept or someone else’s capacitors basically allowing the Zinc batteries to constantly charging the L/A batts or capacitors while they release the bursts of power that an EV needs. But even then. The TT Zero bikes are emptying their packs in 20 minutes. That’s 3C constant. Not to mention that even though it gets us a Lightning with 37.7kWh, albeit a bit heavier, but it’s still not the 55-60kWh I think elmotos need to compete with MotoGP bikes, at the same weight (170lbs lighter than it is now).
It’s such a great product, but just not for us elmoto guys. When I build a street bike in my head I always think of my VFR first. Basically a 500lbs bike with a 75kWh (or 100hp) motor. So, a 30kWh pack would need a 2.5C rate. But then I think a 150kW (or 200hp) “liter” bike might need a a smaller pack for less weight, so a 25kWh would need a 6C rate. These types of bikes will stay in the realm of lithium batteries. There might be some hope for touring bikes. Can you imagine an electric Goldwing, costing way less than a GSX-R? We’ll just have to wait for lithium-air. [sigh]