Maxwell 350F supercapacitor: D cell form factor, 6 Wh/kg energy density

[anorlunda]

I'm impressed by the specifications of the newest capacitors. They are sold in the form factor of a D cell battery for at little as $8 each. I have no question. I'm just amazed at how fast that technology is improving. It may be time to consider applications for capacitors that we pooh-poohed before as unrealistic.

Capacitor versus lead-acid battery
Energy density 6 Wh/kg versus 33-42 Wh/kg.
Power density 4600 W/kg versus 180 W/kg.
Cycles 500000 versus 500.
Leakage 0.3 mA versus 3-20%/month self-dischargea

Here are some specs quoted for the capacitors.

• Brand：MaxWell33-42
• Rated Voltage：2.7V
• Rated Capacitance：350F
• Capacitance Tolerance：0%~10%
• ESR(DC)：3.2mΩ
• Maximum Continuous Current (at 15℃)：35A
• Maximum Peak Current：220A
• Maximum Leakage Current (72hrs/mA)：0.3mA
• Power Density (W/kg)：4600
• Maximum Energy (Wh)：0.35
• Energy Density (Wh/kg)：5.9
• Operating Temperature range：-40℃~65℃
• Storage Temperature range：-40℃~65℃
• Weight (g)：63.3
• Size (ΦD×L/mm)：33.3×61.5
• Cycle Life：≥500000

 

[Averagesupernova]

I too am amazed by the energy that can be packed into such a small package as compared to say 20 years ago. Often times these super capacitors are not suitable for anything except memory backup or something similar due to a high ESR but even that is shrinking down.

 

[meBigGuy]

I'm impressed.
The .0035 ohm esr is calculated after 15 seconds at a 35 amp load. In the "olden days" you couldn't get all the charge at a high current.
Just for perspective, 350F means 1 amp for 35 seconds drops 0.1v. That's wild!