Inte illa 64 Wh/kg är det något bättre är NiCd enligt
http://batteryuniversity.com/learn/arti ... ithium_ion Citat:
Figure 10: Typical energy densities of lead, nickel- and lithium-based batteries
Lithium-cobalt enjoys the highest specific energy; however, manganese and phosphate are superior in terms of specific power and thermal stability.
Courtesy of Cadex
Det är dock svårt att utnyttja all energi i en kondensator eftersom spänningen sjunkar lineärt med laddningsgraden, se
http://batteryuniversity.com/learn/arti ... rcapacitorCitat:
The discharge curve is another disadvantage. Whereas the electrochemical battery delivers a steady voltage in the usable power band, the voltage of the supercapacitor decreases on a linear scale from full to zero voltage. This reduces the usable power spectrum and much of the stored energy is left behind. Consider the following example.
Take a 6V power source that is allowed to discharge to 4.5V before the equipment cuts off. With the linear discharge, the supercapacitor reaches this voltage threshold within the first quarter of the cycle and the Remaining three-quarters of the energy reserve become unusable. A DC-to-DC converter could utilize some of the residual energy, but this would add to the cost and introduce a 10 to 15 percent energy loss. A battery with a flat discharge curve, on the other hand, would deliver 90 to 95 percent of its energy reserve before reaching the voltage threshold.
Skriver det något om sjävurladdningen? Det lär utöver låg energidensitet, urladdningskurvan och höga kostnader vara en achilleshäl av supercondensatorer
Citat:
The stored energy of a supercapacitor decreases from 100 to 50 percent in 30 to 40 days. A nickel-based battery self-discharges 10 to 15 percent per month. Li-ion discharges only five percent per month.
50-100% självurladdning i 30-40 dagar skulle alltså göra energiförlusterna i elbilar ökade markant.
En fördel med supercaps är att de i motsats till litium batterier borde klara av att bli helt urladdade utan att förstöras, men man måste ändå ha elekronik som övervakar (över)spänningar och jämnar ut cellernas (o)balans annars kan det smälla ganska hård.
/Aryan