( ( ( ( ( ( The battery ) , ) ( as ( well as ) ) ) ( ( the rest ) ( of ( ( ( the ( bike 's ) ) ( electrical system ) ) ( ( is ( ( ( ( ( DC ( -LRB- ( ( Direct Current ) -RRB- ) ) ) , ) and ) ( an alternator ) ) , ) ) ( as ( ( its name ) implies ) ) ) ) ) ) ) , ) ( ( provides ( alternating ( current ( -LRB- ( ( ( ( the direction ) ( of ( current flow ) ) ) ( reverse periodically ) ) -RRB- ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN battery)) (, ,) (CONJP (RB as) (RB well) (IN as)) (NP (NP (DT the) (NN rest)) (PP (IN of) (NP (NP (NP (DT the) (NN bike) (POS 's)) (JJ electrical) (NN system)) (SBAR (S (VP (VBZ is) (NP (NP (NP (NNP DC)) (PRN (-LRB- -LRB-) (NP (NNP Direct) (NNP Current)) (-RRB- -RRB-))) (, ,) (CC and) (NP (DT an) (NN alternator)) (, ,)) (SBAR (IN as) (S (NP (PRP$ its) (NN name)) (VP (VBZ implies)))))))))) (, ,)) (VP (VBZ provides) (S (VP (VBG alternating) (NP (NP (JJ current)) (PRN (-LRB- -LRB-) (NP (NP (DT the) (NN direction)) (PP (IN of) (NP (JJ current) (NN flow))) (S (VP (VB reverse) (ADVP (RB periodically))))) (-RRB- -RRB-)))))) (. .)))
The battery, as well as the  rest of the bike's electrical system is DC (Direct Current), and an alternator, as its name implies, provides alternating current (the direction of current flow reverse periodically).
(ROOT (S (NP (VBG Alternating) (NN current)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (JJ electric) (NN current))) (SBAR (WHNP (WDT that)) (S (VP (VBZ keeps) (S (VP (VBG reversing) (NP (NN direction))))))))) (. .)))