Forewords
Having got an over-view of a car’s basic electrical system last week, here’re some Do’s and Dont’s to keep them trouble free:
Do’s
- Keep a regular check on the electrolyte level in your battery. Top-up to ‘max’ level, as and when required, using ONLY pure/battery grade distilled water. Overfilling is to be avoided at all costs as the electrolyte/acid will spill over when the battery is getting charged and thus ruin its adjoining areas for good.
- Even the present day ‘maintenance free’ batteries require such attention ~ every 3-6 months and the ‘semi-sealed’ ones once a year or so. Keep its terminals free of sulphate’ deposits and lightly smeared with petroleum jelly.
- Likewise, it’s important to keep an eye on the Alternator drive belt tension since belts tend to loosen with age/mileage. A loose belt can lead to a flat battery after a while, for no fault of the Alternator.
- Switch-off headlamps at night in b2b traffic but leave the parking/tail lights on – wherever possible.
- This way, an OE Alternator can last ~ 50 kkm+ and well branded Batteries ~ 3-yrs before needing any service/attention. As and when needed, entrust the work ONLY to their Authorised Service Centres.
Dont’s
- On the present MPFi/CRDi cars, it’s NOT advisable to retro-fit any electrical accessories, such as music systems, fog/rally lamps, high wattage head lamps, remote/central locking, fancy lights/horns etc that are not ‘OE/Dealer Approved’. If at all, that too only by the Dealer and against a formal receipt. Otherwise, your OE Warranty and consequently the Insurance Cover stands to be annulled for having carried out ‘unauthorised’ modifications – not to mention utter loss of reliability of the vehicle.
- It’s commonly advised out of ignorance even in prominent Media that using ‘relays’ for retrofitting high wattage accessories will solve the problem. Nothing could be farther from truth as – a) this’d inevitably involve tampering with the OE Wiring Harness that’s a taboo for MPFi/CRDi’s and b) a relay is just a ‘passive’ switching device that can only increase the load switching ‘capability’ of the OE switches and therefore, the additional electrical load in terms of Amps/Watts has to come from the Battery and in turn the Alternator only.
- The present day cost-competitive ‘edge’ designs leave hardly any room for such overloading, including the OE wiring. In plain speak, it’s asking for trouble – relays or no relays.
- Some vitals of a car such as the Starter, Horns, Brake Tail Light Bulbs, are NOT ‘continuously’ rated - like a household Mixie - as their application doesn’t warrant so. Therefore, cranking a Starter repeatedly for more than 3-4 secs at a stretch can considerably shorten its life, along with that of the Battery. Ditto for Horns. They should be ‘tooted’ only in short bursts. Likewise, don’t rest your foot on the brake pedal when parked or waiting at traffic lights. Instead, shift to neutral and engage the parking brake fully BUT don’t forget to release it when taking off!
Forewords
Development of a rechargeable Battery in the ‘20s revolutionised the Electrical System of a Car thereafter. Today, particularly in the luxury sedans’ of the west, they can be as complex as in a long-haul passenger jet airliner – deploying some kilometers of specialised wiring, relays and switches.
Electrical problems like a flat battery or malfunction of the key parts are most frequent that plague an average motorist. So sooner one understands the basics, the better for him and his vehicle. Due to space constraints, this one is split into 2-parts – Part 1 covering the basics and Part 2 some Do’s and Don’ts.
Some Basics
The ONLY source of ‘power’ in a conventional vehicle is its engine. Therefore, its Alternator and in turn the Battery are ‘secondary’ sources, ‘powered’ by the engine. Today, all cars have 12V DC Systems whereas heavy commercial vehicles deploy 24V DC for understandable reasons.
Flow of electricity in a circuit is like flow of water in a stream, where ‘velocity’ of stream (kph) is equivalent to system ‘voltage’ (V) and rate of flow (cusecs) is eqvt to current in ‘Amperes’ (A). Further, an electrical ‘load’ is measured in ‘Watts’ (W) and in a DC system, it’s a product of VxA.
Battery
The fundamental requirement of a car battery is to provide reliable power to its ‘starter-motor’ and its Ignition System, to fire the engine even under most adverse conditions – such as sub zero temperatures, prolonged shut downs, poor state of engine health etc.
Therefore, a car battery is ‘sized’ accordingly i.e. higher the power required to ‘crank’ the engine, ‘larger’ (AH) the Battery. Typically, a battery type ‘NS40S’ has an AH capacity of 30@20 hrs. In other words, such a fully charged battery can deliver 1.5 Amps for 20-hrs.
It’s note worthy that ‘A’ and ‘H’ are not always inversely proportional i.e. if such a battery is discharged @ 5 Amps, it’ll last < 6 hrs!
Alternator
Having got a suitable Battery on-board, it’s logical that it’d need to be kept fully charged, as it gets substantially discharged every time the engine is cranked. Until mid-‘60s, this job was done by a ‘dynamo’ but as load demands increased, it was found wanting in more ways than one – such as inability to charge at low/idling engine speeds and relatively short/unreliable life due to the ‘commutator’ it had to have, to convert the basic ‘AC’ it generated into ‘DC’ for use on board - coz the Batteries are DC only.
This need paved way to development of ‘Alternators’ that overcome such deficiencies, where wear-prone ‘commutator’ got replaced with a solid-state ‘Rectifier Plate’ and its external electro-mechanical ‘Voltage Regulator/Cut-out’ got replaced with in-built (solid state) voltage regulator – to maintain the Alternator output within 12-15 Volts regardless of the engine RPM.
Today’s average sedans have Alternators with an output capacity of ~ 60 Amps/15 Volts a/a 20 Amps of Dynamo’s of yore and are so designed that they’re able to meet practically all the ‘designed’ electrical loads of a car while on the move, including while idling at traffic lights, and yet have required spare capacity to keep the battery fully charged at all times
