TECH: TORQUE SHOP #9

Our me­chan­i­cal en­gi­neer an­swers a few bat­tery-re­lated ques­tions.

Torque (Singapore) - - CONTENTS - Does a car with a stop­start sys­tem have a higher

Our me­chan­i­cal en­gi­neer an­swers a few bat­tery-re­lated ques­tions.

HHOW of­ten do I need to change my car’s bat­tery? With stop-start sys­tems, is there more wear on the bat­tery and starter mo­tor? Gen­er­ally, car bat­ter­ies should last at least one year, al­though nei­ther car man­u­fac­tur­ers nor bat­tery-mak­ers ever de­clare a bat­tery’s life­span.

Try to re­place your car’s bat­tery with a main­te­nance­free bat­tery which has an in­di­ca­tor show­ing its state of charge, so that you can be aware of its health.

If you sel­dom open your car’s bon­net, then the best ad­vice is to re­place your car’s bat­tery ev­ery year, but that does not mean car bat­ter­ies have a life­span of only 12 months. Th­ese days, many cars come with stop-start sys­tems, which de­mand more elec­tri­cal en­ergy. Such cars have more ef­fi­cient al­ter­na­tors, heavy­duty starter motors and spe­cially de­signed bat­ter­ies.

The al­ter­na­tor is de­signed to cope with fre­quent start­ing and, hence, charges the bat­tery more rapidly. It is the same with the starter mo­tor, which is built to sus­tain fre­quent starts with­out over­heat­ing.

More im­por­tantly, where a stop-start sys­tem is in­stalled, a con­troller man­ages stop­start ac­tiv­ity based on bat­tery state and will never al­low the sys­tem to op­er­ate if a lowen­ergy level is de­tected.

Stop-start sys­tems, there­fore, do not de­mand sig­nif­i­cantly higher main­te­nance. But you should take note that bat­ter­ies used in cars with a stop-start sys­tem are costlier. They use ei­ther En­hanced Flooded Bat­tery tech­nol­ogy or Ab­sorbent Glass Mat bat­ter­ies.

Nei­ther tech­nol­ogy is new. Ab­sorbent Glass Mat bat­ter­ies have been used in in­dus­trial ma­chines for some time and are com­monly found in emer­gency gen­er­a­tor sets.

THE BEST AD­VICE IS TO RE­PLACE YOUR CAR’S BAT­TERY EV­ERY YEAR, BUT THAT DOESN’T MEAN CAR BAT­TER­IES HAVE A LIFE­SPAN OF ONLY 12 MONTHS.

chance of stalling? Some of th­ese cars come with no­tices on the sun­vi­sors ad­vis­ing what driv­ers should do if the en­gine does not restart. This is a bit of an irony be­cause stop-start sys­tems go through pe­ri­ods of “stalling” that are in­de­pen­dent of the driver or the con­di­tion of the en­gine. Unini­ti­ated en­gine shut­down is now stan­dard fare in a num­ber of cars, in­cor­po­rated to re­duce fuel con­sump­tion when wait­ing, as at traf­fic light junc­tions.

When this oc­curs, your en­gine has ef­fec­tively “stalled”. Start-up is au­to­matic the mo­ment you re­lease the brake pedal. The fea­ture can be de­ac­ti­vated by the driver. How­ever, some mo­torists are con­cerned that the en­gine will not restart when it should.

If the en­gine in­deed does not start up au­to­mat­i­cally, then switch off the ig­ni­tion and start up as you nor­mally would. En­sure the trans­mis­sion is in Neu­tral or Park when do­ing this.

Stop-start sys­tems are de­signed with a num­ber of fail-safe fea­tures to pre­vent a total shut­down. For ex­am­ple, when the bat­tery is weak, stop-start will not ac­ti­vate.

For now, there is no hard ev­i­dence to sug­gest that a car with such a sys­tem has a higher chance of stalling. What are the pos­si­ble rea­sons for er­ratic idling? Also, I have no­ticed that at night with the head­lights on, the idling speed slows down even more, while the lights stay very dim and brighten con­sid­er­ably only when I rev the en­gine.

Is this an en­gine prob­lem, an elec­tri­cal prob­lem or both? The most likely cause for the symp­toms de­scribed above is a low volt­age sup­ply.

This will of­ten cause the en­gine con­trol unit to func­tion a lit­tle ab­nor­mally, re­sult­ing in a lower than nor­mal idle speed. Low volt­age will def­i­nitely cause lights to be dim, too.

The first thing to check in rec­ti­fy­ing the prob­lem is the con­di­tion of the bat­tery. If it is weak, re­place it im­me­di­ately. Some­times, the prob­lem may just be loose bat­tery ter­mi­nal con­nec­tions. Make sure th­ese are clean and tight.

Of­ten ne­glected is the earth cable that runs from the neg­a­tive bat­tery ter­mi­nal to a se­cure point on the car’s body or chas­sis. Many elec­tri­cal prob­lems are caused by a weak earth con­nec­tion. Have the cable checked and re­placed, if nec­es­sary. It can de­te­ri­o­rate over time.

Fi­nally, check the con­di­tion of your ve­hi­cle’s al­ter­na­tor, which should sup­ply 14 volts to the bat­tery when the en­gine is run­ning at its nor­mal idle speed.

Re­place­ment bat­ter­ies for cars with a stop-start sys­tem are more ex­pen­sive than reg­u­lar car bat­ter­ies.

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