Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Patent
1997-12-22
2000-03-14
Wong, Peter S.
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
324427, H02F 700
Patent
active
060377496
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a battery monitor. It has a capability for monitoring and displaying the state of charge in a battery and particularly has a capability for holding and then releasing at least some charge in a vehicle storage battery.
BACKGROUND
Many publications describe means to monitor the residual charge in batteries and in particular automotive batteries, where the amount of charge remaining may determine whether or not the battery can be used at a later time to drive a starter motor and effectively start an engine.
Also, a discharged lead-acid battery will deteriorate (known as sulfation) rapidly. There are many other applications of batteries where it is desirable to know the amount of residual charge in the battery, for example batteries used for cell phones, or for emergency equipment.
Although modern motor vehicle batteries have progressively improved in capacity there remains a risk that the battery can be accidentally discharged, for example, by leaving the lights on when leaving the vehicle or in other similar ways. Thus the driver on returning to the vehicle will not be able to start the engine because insufficient voltage or capacity remains in the battery to turn the starter motor or to provide sufficient power to the spark plugs, for example, to provide a usable spark. This can of course can be extremely inconvenient for the driver. In some situations, for example, in extreme weather conditions or in localities offering high personal risk a flat battery can be actually dangerous.
Some attempts have been made to overcome this problem, for example, by providing what are in effect double batteries or pairs of batteries but such arrangements may not solve the problem in all circumstances as an opportunity for the starting battery or for the vehicle starting cells to go flat, still remains.
Paredes (U.S. Pat. No. 4,020,414) is one of many inventions that uses battery voltage during discharge as a gauge of capacity, to warn the user of potential failure. These are in effect narrow-range voltmeters for the 11-12 V range, and assume use with a 12 V battery. Paredes uses an array of lamps as a voltage display. Paredes teaches (as in his FIG. 3) that there is a gradual decline of cell voltage as the level of charge is reduced. Stevens (U.S. Pat. No. 4,028,616) includes with his voltmeter a method for measuring voltage under no load and then after a ten-second engine start routine, in order to assess battery condition.
During research for this invention the problem of relying solely on voltage as per the above prior art was realised. It gives too inaccurate a cutoff point.
Sheldrake (U.S. Pat. No. 4,493,001) teaches a motor battery rundown protection system which does include disconnection and reconnection means but this system has only voltage sensing means. The same can be said for Sloan (U.S. Pat. Nos. 4,902,956 and 5,332,958).
DEFINITIONS
"A critical load" is a term used to refer to an important use of battery charge, such as for turning over an internal-combustion engine as part of an engine starting process.
"A non-critical load" is a term used to refer to a less important and possibly inadvertent use of battery charge, such as for running headlights, parking lights, or a radio.
"A defined type of battery" refers to a set of batteries having substantially similar voltage/current/state of charge characteristics, and for example refers in general to the class of conventional lead-acid storage batteries as are used in petrol or diesel-driven cars and similar road vehicles. (Some individual products may differ in characteristics from the majority; perhaps due to different details of design). Sealed, gel-electrolyte lead-acid storage batteries may comprise a different set, and nickel-cadmium rechargeable batteries are likely to comprise a different set.
OBJECT
It is an object of this invention to provide an improved means for monitoring a battery, or at least to provide the public with a useful choice.
STATEMENT OF THE INVENTION
In a first broad
REFERENCES:
patent: 4558281 (1985-12-01), Codd et al.
patent: 5345392 (1994-09-01), Mito et al.
patent: 5518835 (1996-05-01), Simmonds
patent: 5726553 (1998-03-01), Waugh
Batteryguard Limited
Toatley , Jr. Gregory J.
Wong Peter S.
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