Qaphela ukukhishwa kwebhethri le-lithium kanye nokushaja ngaphansi kokushisa okuphansi. Uma izinga lokushisa elizungezile liphansi kakhulu, imodyuli yokushisa izoshisa ibhethri le-lithium kuze kube yilapho ibhethri lifinyelela izinga lokushisa lokusebenza lebhethri. Ngalesi sikhathi, ama-bms ayavuleka bese ibhethri lishaja futhi lishaja ngokujwayelekile.