Hint

Hint-2

1. A battery is built from four series-connected lithium-ion battery cells, where each cell has operational voltage limits V min = 2.5V and Vmax = 4.2V. If the present signed charge current limits of the four cells, computed via the HPPC approach, are (-85A, -81A, -83A, -82A), what is the overall battery-pack absolute charge power capability (in W)? Round your answer to the nearest Wand report a positive number. Enter answer here 2. Consider a two-cell series-connected battery pack where cell states of charge are z1 = 0.99 and z2 = 0.97 and where the cells have total charge capacity Q1 = 319h and Q2 = 32Ah. If zmin = 0.1, what is the maximum value for Zlow (that is, max; (Zlow.;)) for this battery pack (in percent)? Round your answer to the nearest percent. Enter answer here cell; dis Computing battery-pack available power I Recall that HPPC cell discharge power is computed OCV(zj(t)) Umin PS = v;(t)i;(t) = Umin Rdis, AT,j Computing power in series multi-cell battery pack, still clamp v(t) = Umin But, must use minimum limiting current, multiply by number of cells in series Ns OCV(zj(t)) - Umin (t);(t) = NUmin mn | j Rdis,AT,j j=1 I Similarly, for charge (remembering charge power is negative) Ng OCV(zj(t)) - Vmax = v;(t)ij(t) = NgVmax max Rchg,AT,j j=1 pack dis p pack chg LOCVCE) d QVnoma Computing battery-pack total energy Recall that cell total energy is computed as z(t) E(t) = Q Az Zmin In a battery, each cell may have different Q; and zj(t) Computing battery-pack energy is a three-step process 1. Determine minimum Ah to discharge any cell to Zmin Start with generic SOC equation z(t) = z(0) - Ah discharged/Q Set z(0) = z;(t), z(t) = Zmin, = Zmin, Q = Qj, rearrange Ah discharged = min Q; (zj(t) Zmin ) Zlow Zmin