David Cowan
Daniel Shaw
Battery Capacity
The duration of time which a battery can withstand a constant draw of one Amp while maintaining a constant voltage
(output)
Battery Capacity quantifies the amount of useable energy that a battery can
store
Battery Capacity
Battery Capacity is expressed in units of Amp hrs
Units
Constant discharge
Time in hrs of a full discharge
The total efficiency of a battery is expressed in Watt hrs
Units
Battery Capacity
Desired Output in Volts
Available Capacity (Puekert’s Law)
Current of discharge
Time in hrs of a full discharge
Peukert’s Constant (only for lead acid batteries) *not spring constant!*
* Puekert’s Constant is always
Battery Capacity is additive when batteries are arranged in parallel but not when arranged in series
Battery Arrangement
Doubled Capacity
Doubled Output
Battery ArrangementHowever, if you arrange multiple batteries in a way so that you have a series of parallel batteries, then you can double both the output and the capacity
One of the dangers of having an EV with a Lithium Ion battery is; battery gassing. Battery gassing occurs when you overcharge the battery. This leads to thermal runaway which is essentially when your battery heats up so much that it explodes
Battery Gassing
Our ZAP car has six 12V Absorbent Glass Mat (AGM) deep cycle Lead Acid Batteries which take 100hrs to fully discharge
The ZAP Car
The ZAP Car
𝑇𝑜𝑡𝑎𝑙 𝑃𝑜𝑤𝑒𝑟=(100 A ) (72V )=7200WatthrsThe ZAP Car
For our ZAP Car
Battery Efficiency
Time it takes to fully discharge at this this rate
Rate of discharge
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