At Upgrade Energy, we spend a lot of time thinking about one thing: how to deliver more power, more reliably, in the real world, not just on paper.
Over the last few months, it has become clear that a lot of the applications we are supporting are pushing harder than ever. Higher bursts. Longer sustained loads. Tighter packaging. Tougher environments. So, we are doing what we do best.
We are switching gears.
Today, we are excited to introduce our next step forward: RED Series V4, a new product line built around Amprius Technologies SA124 high power 21700 lithium-ion cells.
Why we built RED 21700 Series V4
The honest answer is that the bar moved.
Customers want stronger bursts without voltage sag, high output that holds up over time, compact packs that manage heat well, and performance you can count on cycle after cycle. RED Series V4 is our response, a new platform designed to hit those goals head on. We trust Amprius’s supply chain capabilities to support this platform at scale, ensuring reliable, high-volume availability as demand grows.
Why the Amprius SA124 cell
At the center of V4 is the Amprius SA124 SiCore rechargeable lithium-ion cell, a 5Ah high power 21700 format designed for serious current delivery.
Here is what stood out to us.
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It can really push current
The SA124 supports up to 50A continuous discharge and up to 60A pulse discharge for up to 30 seconds. -
Strong energy density in a familiar form factor
The SA124 is rated at 5000 mAh typical capacity with a nominal voltage of 3.6V, and it delivers 260 Wh/kg and 690 Wh/L energy density at C/5. It is a 21700 cell format with dimensions of 21.70 ± 0.2 mm diameter and 70.80 ± 0.3 mm length. -
Built for real operating conditions
A discharge temperature range of minus 20°C to 80°C, and a charge temperature range of 0°C to 45°C. -
Cycle life that matches high power use
The SA124 delivers about 900 cycles to 80 percent state of health at +1C charge and -1C discharge with 100 percent depth of discharge at room temperature. It reaches about 500 cycles to 80 percent state of health at +2C charge and -4C discharge with 100 percent depth of discharge at room temperature.
What this means for RED Series V4
RED Series V4 is not just a cell swap. We are building a platform around what this cell does well. That includes high burst and sustained power, thermal aware architecture for demanding duty cycles, repeatable performance over real usage, and integration friendly design for teams shipping products.
Certifications note
The SA124 data sheet lists UN38.3 and CE, with IEC62133 marked as planned for Q1 2026. As always, pack level compliance depends on your final configuration and requirements.
Want to talk V4
If you are working on an application where power output is the bottleneck, or you are tired of packs that look good on a spec sheet but fall apart under real loads, we would love to chat.
Reach out to get early RED Series V4 details, sanity check your power and thermal profile, and talk fit, availability, and next steps.
Cell specifications referenced above are from the Amprius SA124 Preliminary Technical Data Sheet: link.
