Low pressure nickel hydrogen battery

DETAILED DESCRIPTION The specific embodiment of a 20 kilowatt-hour battery system is described with reference to the symbolic diagram of FIG.
1.
The stack 10 comprises several nickel-hydrogen cells, such as shown in FIGS.
2 and 3.
Each cell has an individual gas line 12 extending into the interior thereof.
A manifold 14 connects all of these individual gas lines to a common low pressure line 16.
The stack 10 also has positive and negative electric terminals 18.
The hydrogen is stored in gas bottles 20 at a pressure of up to 1950 psi (pounds per square inch).
The gas lines from the bottles are connected to a common high pressure line 22.
The low pressure line 16 and high pressure line 22 are connected via parallel discharge path 24 and charging path 26.
A pressure gage 30 connected via a branch to line 22 indicates the bottle pressure, which is a measure of the state of charge of the battery system, and thus is equivalent to a fuel gage.
The discharge path 24 includes a valve 32 and a pressure regulator 34.
The charging path 26 includes a valve 36 and a pump 38.
During discharge, valve 32 is open and valve 36 is closed.
An electric load (e.
g.
vehicle motor not shown) is connected to the terminals 18.
The regulator receives the hydrogen gas at high pressure, and delivers it at a fixed low pressure for use in the cells of stack 10.
This low pressure may be at a gage pressure as low as five psi, and up to about 100 psi.
A pressure of 65 psi would be satisfactory.
During charge, valve 32 is closed and valve 36 is open.
An electric charger circuit (not shown) is connected to terminals 18.
The electric supply is also connected to operate the motor of pump 38.
The pump operates only during charge, to pump the hydrogen evolved by the cell stack 10, and deliver it at high pressure for storage.
During standby in a charged state, both valves 32 and 36 are closed, which prevents significant self-discharge.
A pump 38 for 3.
1 cubic inches, requires 450 revolutions per minute for a four hour recharge.
A suitable pump is listed in the 1980 McMaster-Carr catalog