By-pass for internally open-circuited cells

Claim 1

A means for automatically establishing a low resistance shunt or by-pass around a battery cell unit, said means comprising: a. two electrical conductors, each having first and second ends, the first end of one being adjacent to but separated by a gap from the first end of the other; b. a closed ampoule containing an electron-conductive material and having a generally tubular skirt extending therefrom, the portion of the wall of said ampoule defined by the juncture therewith of said skirt being a fragile, thin-walled portion shaped and dimensioned so that it will rupture at a lower internal pressure than the rest of said wall; and said material being in an amount and so composed that, if heated to a temperature (T 1 ), it will exert enough pressure to rupture said ampoule wall portion, c. electrically non-conductive sealing means, sealingly engaged with said first conductor ends and with said skirt, and--together with said ends, said skirt and said fragile wall portion--defining an evacuated chamber which comprises or communicates with said gap; d. means, automatically responsive to the potential difference between said second ends of said conductors, for heating said material to temperature T 1 when said potential difference rises to a pre-selected voltage; the above recited components a-d being so sized, shaped, composed and arranged that (1) said by-pass will not be damaged by thermal stresses which develop when it is heated to a temperature as high as T 1 , and (2) when said rupture occurs, said material will flow into said gap, thereby forming an electrical connection between said conductors and completing said shunt.