CA1058286A - Recreational vehicle converter-battery fast charge circuit - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A direct current power supply system for recreational vehicles having an auxiliary chargeable battery wherein a trans-former powered converter is utilized to rectify alternating current into direct current, and where the circuitry includes a battery fast charging circuit and control utilizing sensing means for automatically terminating battery fast charging upon predetermined conditions being attained. Fast charging of the battery 18 accomplished through a converter transformer of eco-nomical construction having a variable voltage output controlled in dependence by the fast charging operation.

Description

.~58Z~
- 1~ The invention pertains to the field of recreational ve-

2. hicle power supply systems using rechargeable battery circuits.

3, Recreational vehicles, such as travel trailers~ motor

4, homes~ and campers, and watercraft such as boats and houseboats,

5, are often provided with dual electrical systems. Lights, and

6, many of the light duty appliances, such as water pumps, usually

7, operate at 12 volts DC, while the heavy duty equipment, such as

8, air conditioners~ television sets, and some refrigerators, re-

9, quire 120 volt AC electrical power. While some of the larger

10. vehicles employ generators and auxiliary engines for producing

11. electricity, the ma~ority of "self~contained" recreational ve-

12. hicles and boats employ aux~liary rechargeable batteries and

13. converters to energize the unit~

14, A recreational vehicle converter includes a transformer

15. having a primary coil connectible to an A~ power supply. The

16. transformer secondary coil energi~es a rectifying circuit such

17. that the converter has an approximately 12 volt direct current

18. output which ls connected to the recreational vehicle load cir-

19. cuit. As the vehicle battery is also of 12 volts the lighting

20, and low voltage circuit of the recreational vehicle ~ay be

21. selectively powered by the battery, or the converter output.

22. With such recreational vehicle circuits it is common to utilize

23. means for switching between battery and converter operation,

24. and the circuitry usually employs a slow or trickle battery

25~ charging circuit supplied from the converter output for re~

26, charging the auxiliary vehicle battery during converter opera-

27. tion as powered from an alternating current power source.

28. It is not unusual for the vehicle auxiliary battery to

29. become substantially discharged due to extended use while the

30. vehicle is in the field and accessibility to alternating current

31~ is not possible. Accordingly, when the vehicle is at a location

32, ~Jhere alternating current is available it is often desired to

33. quickly bring the auxiliary battery to a fully charged condition, 1. and~ with known techniques~ a battery fast charge may be con 2. nected to the vehicle alternating current supply for bringing 3, the auxiliary battery to a full charge in a relatively short 4, time~ However, the rapid charging of wet cell rechargeable 5, batteries presents certain well known hazards and conditions, 6. and the rate and duration of fast charging must be closely con-7, trolled in order to prevent damage to the battery or the forma-8. tion of explosive gases, 9, Both cost and slze are significant factors in the design-10. ing of recreational vehicle electrical cireuits and to utilize 11. a plurality of transformers and rectifiers to attain selective 12. recreational vehicle load operation~ as well as permit slow and 13. fast charging, is prohibitive in many instances, and heretofore 14, a recreational vehicle direct current power supply system ca-15. pable of both slow and fast charging has not been available 16. which is of a minimum cost and size, dependable and safe ln 17, operation and readily operable by the unskilled.
18. It is an obJect of the invention to provide a recrea-19. tional vehicle direct current power supply system utilizing a 20 9 battery fast charge circuit wherein a single converter may be 21. utilized to supply the recreational vehicle load with direct 22. current, energize a battery slow charge circuit, and also 23. selectively and automatically control a battery fast charge 24. circuit.
25. Another object of the invention is to provide a multi-26. purpose converter of alternating current to direct current hav^
27. ing high and low direct current voltage outputs automatically 28. controlled in accordance with the operation of a battery fast 29. eharge circuit.
30, An additional object of the invention is to provide a 31. recreational vehicle direct current power supply system employ-32. ing a converter having a primary coil wherein the number of 3, effective turns may be regulated to vary the voltage output of ~if328~;

1, the converter in accord with the condition of operation of a 2, battery fast charge circuit, 3. A further object of the invention is to provide a recrea-tional vehicle direct current power supply system which permits 5. a slow charge o~ the vehicle auxiliary battery at all times dur-6, ing energizing of the converter~ and wherein energizing Or the 7. converter automatically connects the vehicle load circuit to the ~. converter output and the battery fast charging circuit is con-9. trolled independently of the battery slow charge circuit.
10, Another ob;ect of the invention is to provide a recrea-11. tional vehicle direct current power supply system utilizing a 12. rechargeable battery and a fast char~ing circuit wherein the 13. characteristics of the battery during charging are sensed~ and 14. guch characteristics are utilized to automatically terminate 15. the fast charging operation. Auxiliary vehicle battery voltage, ~6. temperature and water level are simultaneously sense~, and upon 17- any of these three characteristics attaining a predetermined 18. limit, fast charging of the battery automatically ceases.
19. Another obJect of the invention is to provide a recrea-20. tional vehicle direct current power supply system ut~lizing a 21. converter powered battery fast charge circuit which is auto-22. matically terminated upon the battery reaching predetermined 23. conditions, and wherein initiation of the fast charging cycle 24. is manually accomplished, 25. In the practice of the invention the converter trans-26. former includes a primary coil which is tapped and is selec-27. tively connected to an alternating current power source whereby 28. a greater or lesser number of primary coil turns may be ener-29. gized~ This selective operation of the prlmary coil output 30. selectively produces high and low direct current voltages from 31. the converter, and the batter~y fast charge control circuit de-32. termines the mode of connect~on of the primary coil to the ~3. alternating current power source. During fast charging the 1- converter is connected to the alternating current source to 2- produce a lower voltage direct output, and the battery is cli-3- rectly connected to the converter output during the fast charg-l, ing operation.
5- The battery voltage, temperature and water level are 6- sensed during fast charging, and upon any of these three con-7- ditions reaching a predetermined value a relay switch is automa-~- tically actuated which simultaneously disconnects the battery 9- from the converter output, and increases the voltage of the 10. converter by switching the primary coil to its minimum coil 11. energization, 12. The circuit includes a slow charge for the vehicle 13- battery which is automatically slowly charging the battery 14. whenever the converter is energized, and the fast charge con-15. trol circuit utilizes a manually initiated holding switch for 16. maintainin~ the fast charging operation which is under the auto-17. matic control of the fast charge control circuit as influenced 1~- by the battery sensing devices, 19. The aforementioned ob~ects and advantages of the inven-20, tion will be appreciated frorn the following description and 21. accompanying ~rawing w~lerein a recreational vehicle direct cur-22. rent power supply system in accord with the invention is illus-23. trated with the switch elements shown in the battery power con-24. dition.
25- With reference to the figure~ an alternating current 120 26- volt, 60 cycle power supply includes conductors 10 and 12~ The 27. recreational vehicle converter 14 utilizes a pair of similar 28. transformers, which in effect, can be considered as a single 29. transformer, and the connection of the primary coils thereof to 30. the alternating current supply is controlled by a solenoid oper-31. ated relay switch 16. The circuit includes a second solenoid 32. operated relay switch 18 which is connected to the output of ~3. the converter, and is energized whenever the converter is con-~513;2~

1. nected to an alternating current source. ~he battery charging 2. control circuit is ~enerally indicated at 20, the rechargeable 3. auxiliary vehicle battery is shown at 22, and the recreational 4. vehicle load is indicated at 24.
5- The converter primary coil, or coils, 26 includes a con-6. ductor 28 connec~ed to the conductor 10, while a conductor 30 7- taps into the coil at 139 turns, and the conductor 30 is con-8- nected to switch terminal 32. The condu¢tor 34 is connected 9~ to the end of the primary coil at 167 turns, and is connected 10- by a conductor to the switch terminal 36. As will be appre-11. ciated from the figure the movable switch element 38 is con-12. nected to the AC conductor 12.
13. The converter rectifying circuit l~o is not described in 14. detail as it consists of conventional solid state components 15. for pro~ucing a direct current proportional to the voltage in-16. duced in the converter transformer secondary coilS or coils, 17- 42 by the converter primary coil. The converter direct cur-18. rent output is supplied through conductors 44, 46 and 48.
19. The relay switch 18 includes the solenold coil 50 con~
20. nected to the conductors 114 and 46 whereby the solenoid coll 21. is energized whenever the converter is connected to an AC
22. supply. The re].ay switch 18 includes terminals 52 connected 23. to the slow charge supply conduotor 54~ and also connected to 24. the auxiliary vehicle battery positive electrode 56. The 25. battery negative electrode 58 is grounded to the vehicle. The 26. relay switch 18 also includes the movable elements 60 which are 27. connected to the recreational vehicle load circuit through 28. fuses 62 and conductors 64, and the switch termlnals 66 are 29. connected to the conductor 46 supplied from the converter out-30. put whereby engagement of the elements 60 with the terminals 31. 66 ~irectly connects the recreational vehicle load 24 to the 32. converter output ~uring converter operation~
,30 The relay switch 16 is controlled by solenoid coil 68 ~6~5~Z~

l energized by the battery fast charge control circuit 20 through 2. condu~tors 70 and 72. The coil conductor 72 includes two mo-3. mentary push button switches 74 and 76, the s~itch 71i being 4- normally open~ and constituting the initiation switch for the 5. auxiliary battery fast charge operation, while the normally 6. closed switch 76 permits the fast charge operation to be manu-7. ally terminated, if desired A holding switch 78 is incorpor-8- ated into the relay 16 for maintaining the coil 6~ energized 9. upon the momentary closing of the switch 74.
lO. Direct connection of the vehicle auxiliary battery posi-ll. tive electrode 56 to the converter direct current output is 12. accomplished through switch elements 80 connected to the 13. battery positive electrode. The switch terminals 82 are con-14. nected to the converter output conductor 46. It is to be appre-15. ciated that the coil 68 simultaneously positions the switch 16. elements 38 and 80 and holds the switch 78 closed.
17. The values of the components of the vehicle au~iliary bat-18. tery charging circuit are indicated on the drawing, and the l9. operation thereof will be appreciated by those skilled in the 20. art. Unconventional portions o~ the system are described below.
21. The battery fast charge control circuit includes transis-22. tors 84, 86 and 88, and also includes an illustrated Darlington 23. transistor 90 The transistor 90 may be replaced by a more 24. conventional type, if deslred. The charging control circuit 25. also includes a battery voltage sensing element 92 constituting 26. a thermistor 1n circuit with zener 93, a battery temperature 27. sensing element 94, and a battery water level sensing probe 96 28. directly associated with battery 22. The particular design and 29. construction of the sensing elements may be conventional and form no part of the invention. It is sufficient to recognize 31 that the elements 92, 94 and 96 are of the type wherein the 32. electrical characteristics thereof will vary in a known manner : 3. at predetermined battery voltages, temperature and water level, ~6~5~3Z~

_ 1 res~ectively, and by the use o~ appropriate resitances the 2, outputs of the sensing devices may be used to produce the de-3, sired clrcuit operation.
4, In operation, the circuit components will be in the posi-5, tions indicated in the drawing when the recreational vehicle 6. load is being supplied by the auxiliary battery Z2. Under such 7~ conditions the converter 14 is not connected to an alternating 8. current power source and, thus, the solenoid coil 50 will not 9, be energized. Biasing means, in the form of a spring 98, bias 10, the switch elements 60 to the illustrated position directly 11. connecting the battery electrode 56 to the recreational vehicle 12. load 24. Spring biasing means 100 will maintain the switch 13. elernents 80 of relay 16 disconnected from the terminals 82, and 14~ thus it will be appreciated that only the vehicle battery 22 is 15. energizing the load 24.
16. ~hen the recreational vehicle is accessible to 120 volts 17. AC the same will be connected to the conductors 10 and 12 by a 18. conventional power cord, and the converter 14 will, therefore, 19. be energized. Biasing spring 102 normally maintains the switch 20. terminal 38 in engagement with the terrninal 32 and, thus, the 21. 139 turns of the primary coil 26 of the converter will be ener-22. gized. Accordingly, the maximum direct current voltage output 23, o~ the converter is produced, and the solenoid 50 is energized, 24, as is the battery charging control circuit 20. ~nergization 25, of the coil 50 causes the switch elements 60 to engage the con-26. verter output terrninals 66 disconnectlng the recreational ve-27. hicle load from the auxiliary battery, and connecting the load 28. 24 to the converter output, The converter output is approxi-29. mately 12 1/2 to 13 volts DC, and this voltage provides the 30, proper voltage to operate the load circuit lights and other 31, vehicle low voltage components.
32. At this time there is no interconnection between the 33, ~attery electrode 56 and the converter output, and such inter-~.1135i~Z~

_ 1. connection is to be avoided as the same would result in an ex- 2. cessive charging rate of the battery.
3. If it is desired to fast charge the battery 22 while the 4. converter is in operation the operator momentarily closes 5, switch 74, energizing coil 68~ which closes holding switch 78, 6. and maintains the energizing of the coil. Energizing of coil 7. 68 actuates the switch element 38 to engage terminal 36 ener-8. gizing the 167 turns of the converter primary coil 26. Simul-9. taneously, the switch elements 80 contact the converter output 10, terminals 82 directly connecting the battery positive electrode 11, 56 to the converter output.
12. The switching of the converter primary coils to the 167 13. turns lowers the ~irect current ~oltage output of the converter 14. at conductor 46 9 lowering the direct current voltage to such a 15. value acceptable to the vehicle battery for fast charging pur-16. poses~ but not so high as to damage the battery. At this time 17. approximately 30 amperes are supplied to the battery and fast 18. charging thereof is o¢curring. Simultaneously, the recreation-19. al vehicle load remains connected to the converter direct cur-20~ rent output 21. The solenoid coil 68 remains energized throughout the fast 22, charging cycle, and as the voltage of the battery 22 approaches 23. 15 volts, such condition will be sensed by the voltage sensing 24. zener 95 and this voltage will be imposed upon the SCR97, 25. Attaining the ~esired battery voltage causes the SCR97 to fire 26. dropping the voltage on the transistor 90 to zero terminating 27. conducting of the transistor de-energizing coil 68~ The de-28. energization of the coil 68 causes the switch element 38 and 29. the switch elements 80 to return, under their associated bias~
30. ing force, to the illustrated position restoring the converter 31. to its high voltage direct current output, and disconnects the 32. battery 22 from the converter output. The 15 volts occurring 33. at the battery represents approximately 80% of full charge, and ~5~3~8~

1. this degree of charge is acceptable for most purposes, and pro-2. vides extended battery life. 0f course, by utilizin~ varied 3~ resistances at the sensing means 92 various degrees of charg-4~ lng of the battery to 60% to 100% Or charge may be obtained~
5~ If, durlng the fast charging of the battery 22 9 the tem-6- perature within the battery exceeds a predetermined limit, for 7~ instance 135F., the resistor in the battery temperature sens-8- ing means 94 will change from 1509000 ohms to appro~imately 500 9~ ohms, whlch cuts off the transistor 84. This turnoff of tran 10- sistor 84 wlll allow the base on transistor 88 to rise and 11- transistor 88 will then begin to conduct. This effect provides 12- for a path that will again cause the transistor 90 to shut off 13. due to the effective shortlng of the base of the transistor 90 14- to ground because of the drop across the resistor 104. This 15~ action de-energizes the coil 68 to immediately disconnect the 16. battery from the converter output, and restore the converter to 17- its higher voltage output.
18. In addition to controlling the fast charging circui~ by 19. attaining a predetermined voltage, or excessive temperature 20. rise, the lowering Or the water level within the battery 22 21. will be sensed by the probe 9~. In the event of minimum water 22. level the transistor 86 will turn off causing the transistor 23. 88 to turn on and therefore shut off the transistor 90 and de-24 energize the coil 68 to irnmediately termlnate fast charging 25. and restore to its normal direct current charging rate.
26. It will, therefore, be appreciated that the above des-27. cribed control of the coil 68 provides three separate and dis-28. tinct means for automatically terminating fast charging3 and 29. the likelihood of the fast charging operation damaging the 30. battery 22 is substantially eliminated. This type of automatic 31. control is significantly more advantageous than using a tlming 32. motor to control fast charging as the use of a timer or timing 33. rotor has the disadvantage of possibly producing overcharging ~L~5~!328~

1. as the condition of the battery at the beginning of fast charg-2. ing is difflcult to accurately ascertain.
3. The battery charging circuit 20, through conductor 54, 4. provides slow charging of the battery at a 9 ampere rate at all 5. times that the converter 14 is energized. Thus, when the 6. recreational vehicle is used ~or extended periods of time 7. powered by the converter 14 5 the battery 22 will be fully 8. chargedJ and it is not necessary for the ~ast charge circuit 9~ to be employed. In practice, the fast charging circuit will 10. normally be used when the vehicle is primarily being employed 11. in the field, and 110 volts AC is available for relatively 12. short periods of time, 13. It is appreciated that various modification to the inven-14. tive concept may be apparent to those skilled in the art with-15. out departing from the spirit and scope of the invention, 10 .

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A recreational vehicle direct current power supply system comprising, in combination, converter means for convert-ing alternating current to direct current, said converter means having an alternating current input and output rectifying means selectively having a direct current output of a first normal operating voltage or a second lower fast charge voltage, an al-ternating current power supply connected to said converter means input, first switch means connected to said converter means selectively controlling the output voltage thereof, a recharge-able battery having positive and negative electrodes, second switch means selectively connecting said battery to said con-verter means output second voltage, a recreational vehicle load circuit, a battery fast charging control circuit connected to said converter means output energized thereby having a control output and connected to said battery sensing the voltage there-of, said control circuit control output operatively connected to and controlling said first and second switch means whereby said control output selectively operates said first switch means to produce said converter means second lower fast charge voltage and said second switch means to connect said battery to said converter means output second voltage, and operates said first switch means to produce said converter means first normal operating voltage and said second switch means to disconnect said battery from said converter means output second voltage when said battery attains a predetermined voltage as sensed by said fast charging control circuit, and third switch means selectively connecting said vehicle load circuit to said battery or said converter means output.

2. In a recreational vehicle direct current power supply as in claim 1, a solenoid operating said third switch means and connected to said converter means output for energization there-by whereby said solenoid is energized upon energization of said converter means by said alternating current power supply to dis-connect said vehicle load circuit from said battery and to said converter means output, and biasing means acting on said third switch means whereby de-energizing of said converter means and solenoid causes said third switch means to disconnect said ve-hicle load circuit from said converter means output and to said battery.

3. In a recreational vehicle direct current power supply system as in claim 1 wherein said fast charging control circuit control output energizes a solenoid operating said first and second switch means whereby energizing of said solenoid operates said first switch means to produce said second lower voltage and operates said second switch means to connect said battery to said converter means output second voltage, said charging con-trol circuit including a holding switch operated by said sole-noid and a normally open momentary switch for closing said charging control output to initially energize said solenoid and initiate fast charging of said battery.

4. In a recreational vehicle direct current power supply system as in claim 1 wherein said fast charging control circuit includes battery temperature sensing means controlling said control output to operate said control output upon the battery attaining a predetermined elevated temperature.

5. In a recreational vehicle direct current power supply system as in claim 1 wherein said fast charging control circuit includes battery water level sensing means controlling said control output to operate said control output upon the battery water attaining a predetermined level.

6. In a recreational vehicle direct current power supply system as in claim 1, a battery slow charge circuit having an in-put and an output, conductors connecting said slow charge input to said rectifying means output and said slow charge output to said battery whereby said slow charge circuit is energized to charge said battery upon energizing of said converter means by said alternating current power supply.

7. In a recreational vehicle direct current power supply system as in claim 1 wherein said converter means includes first and second primary coils; said first coil having a greater num-ber of turns than said second coil, said first switch means selectively connecting said first and second coils to said al-ternating current power supply and connecting said first coil to said power supply during gast charging of said battery.

8. In a recreational vehicle direct current power supply system as in claim 7 wherein first and second coils include common turns and said second coil includes a conductor tapping said first coil.

9. A recreational vehicle direct current power supply system comprising, in combination, a converter for converting alternating current to direct current, said converter including a transformer having first and second primary coils and a second-ary coil having an output, said first primary coil having a greater number of turns than said second primary coil, rectify-ing means connected to said secondary coil output having a direct current output, an alternating current power supply, first switch means selectively connecting said first and second coils to said alternating current power supply to selectively produce high and low direct current output voltages, a rechargeable battery having positive and negative electrodes, second switch means selectively connecting said battery to said direct current output low voltage, a recreational vehicle load circuit, a battery fast charging control circuit connected to said direct current output and ener-gized thereby having a control output and connected to said bat-tery sensing the voltage thereof, said control circuit output selectively energizing a solenoid controlling operation of said first and second switch means to disconnect said first primary coil from said power supply and said battery from said direct current output low voltage upon said battery voltage attaining a predetermined value during fast charging of said battery, such operation of said first switch means connecting said power supply to said second coil, and third switch means selectively connect-ing said vehicle load circuit to said battery or said direct cur-rent output, said third switch means including a solenoid con-nected to said direct circuit output whereby said third switch means connects said vehicle load circuit to said direct current output upon energization of said converter by said power supply.

10. In a recreational vehicle direct current power supply system as in claim 9 wherein said fast charging control circuit includes battery temperature sensing means controlling said con-trol output to operate said control output upon the battery attaining a predetermined elevated temperature.

11. In a recreational vehicle direct current power supply system as in claim 9 wherein said fast charging control circuit includes battery water level sensing means controlling said control output to operate said control output upon the battery water attaining a predetermined level.