Safiery Solid State battery – testing begins

Over the last few months, I’ve been hearing some rumbling about Safiery’s new solid state batteries and the sublime specs they offer. So, it was a bit of good fortune when I ran into Bruce Loxton, the man behind Safiery’s impressive mix of products, at the Palm Beach International Boat Show. A short conversation with Bruce left me excited about what the batteries offer and his promise to send me a battery got my wheels spinning. How would I test this battery and just what is it capable of delivering?

Fast forward about two months and I have a 48-volt, 53 amp-hour, 2.79 kilowatt-hour solid state battery in my hot little hands. Hot might be appropriate when you look at some of the data coming out of the battery during my testing. This battery is capable of some pretty sublime rates of power delivery and acceptance. Large amounts of energy in motion builds heat and my early testing demonstrates that.

If you test batteries, Safiery’s specs feel like an invitation to do silly things to the battery. Right there at the top, in big bold letters, Safiery advertises a 3C discharge rate or 150 amps for this battery. Although the battery is rated for 53 amp hours, nearly all of the specs correspond to a rounded off 50 amp-hour capacity. For example, the 3C discharge rate of 150 is correct if the capacity is 50 amp-hours. Additionally, the 50 amp maximum charge rate is 1C at 50 amp hours.

I have done a few capacity tests so far. As is the norm for me, I’ve ended those early tests at higher voltages. I like to understand how the battery operates and verify that all the low voltage protections are working performing a deeper discharge. So, this test ended at 46v or 2.875 volts-per-cell. That’s higher than the generally recognized termination point of 2.625 or even 2.5 volts-per-cell. At any rate, my first test ending at 46 volts yielded a capacity of 50.92 amp-hours.

I highly doubt there is an additional 2 plus amp hours of energy between 46 and 42 volts. Typically, with the sharp knee at the end of discharge, there is little energy to be found past the knee. The blue line in the chart above depicts voltage dropping during the discharge test in question. Around 3:06pm, voltage drops rapidly and accelerates until the session terminates because of low voltage.

My next capacity test, conducted at 50 amps, yielded a slightly higher 51.79 amp hours. That’s still a hair below the rating on the battery. I have more testing to do, but these early test results cause me to wonder if perhaps the battery is built with 50 amp-hour cells and the 53 amp-hour rating represents a best case scenario number. However, to be fair, I am only speculating. Time and a tear-down of the battery should yield more information.

Battery specs detail a maximum cell temperature of 65°C during both charging and discharging. A 1C round trip pushed the battery to 56°C. I have performed a few 3C discharges and found that the cells get very warm. Currently, I’m waiting for the battery to cool enough to do a full discharge and charge test. Previous tests have shown that charging at 1C can’t complete after a 3C discharge without allowing the cells to cool.

The full range

Safiery offers a total of five solid state batteries. All are rated at 2,788 watt hours, and are available in 12, 24, and 48 volts. I haven’t found anything in the specs that clearly states the actual construction of the cells. But, I suspect these are semi-solid state, meaning there is a small amount of liquid or gel in the electrolyte. There are three 48-volt models — although the chart above shows 2 — with discharge rates of 50, 100, and 150 amps or 1, 2, and 3C. The 12 and 24-volt models both carry 1C discharge ratings. Pricing, in U.S. Dollars is as follows: 12v, 217ah – $1,522.73, 24v, 108ah – $1,522.09, 48v, 53ah, 1C – $1,437.93, 48v, 53ah, 2C – $1,641.82, and finally the 48-volt 3C battery sells for $1,710.55 U.S. dollars.

I have plenty to discover about these batteries still. However, based on what I understand and have read so far, Safiery’s batteries differ from the other marine focused player, Solid State Marine. Safiery’s batteries utilize a semi-solid state variety of lithium-iron-phosphate cells. My understanding of Solid State Marine is that their batteries utilize a semi or quasi solid state varient of nickel manganese cobalt oxide (NMC) cells. Solid State Marine’s cells produce higher voltages than LFP. The result is that the 12v version of a Solid State Marine battery sits at potentially troublesome voltages. The Safiery batteries don’t have that challenge.

More testing to come

I plan to continue to work these batteries hard and push the limits of just what they can deliver. The claimed advances in safety alone may be enough to justify the cost premium compared to existing LFP options. Plus, if your power requirements demand the huge power output these batteries can generate, these may enable fewer batteries and a more efficient system.

I’m also looking forward to tearing into the batteries and seeing how it’s all put together. But, in the meantime, Safiery has published a video highlighting some of components and construction methods employed. I’ll be back soon with my own tear-down and much more in-depth testing.