Battery Management Systems
To maximise the life of batteries, it isrecommendedthatallbatterypowered electric vehicles include a BMS,thepurposeofwhich is tomake sure the batteries remainswithintheiridealworkingparameters. Some battery chemistries (suchasleadacid)are fairlytolerant of abuse, but all batteriesbenefitfromhavinga BMS, andit will pay for itself with longerbatterylife.Lithiumand NiMHboth require a BMS for safetyreasons,asthey canbe damagedif overcharged or overheated.
Some typical functions of battery management systemsinclude:
Charge balancing, to make sure all cells finishchargingatthesametime and to prevent damage throughovercharging.
Active balancing, where energy is divertedfromstrongercellstoweaker cells, to make sure all cellsreachtheirmaximumdischargepoint at the same time.
Temperature monitoring, to avoid damage duetooverheating.SomeBMSesmay also control a heater to bringcoldbatteries up toabetterworking temperature.
Low-voltage cut-off, a means of isolating thebatterypackwhenanycell reaches it's minimum recommended voltage,toavoiddamagedueto over-discharging.
State-Of-Charge monitoring for all cells,throughvoltageandcurrentmonitoring the remaining capacity ofeachcellmaybecalculated.