z7 QA test

General questions

• Why has my battery gone flat?

  There can be many reasons why a battery has gone flat - here are the most common causes:

  • Undercharging - This is the most common cause of a flat battery. Modern vehicle charging systems are designed to reduce CO₂ emissions and improve fuel economy by increasing battery usage, while at the same time not providing sufficient charge to fully recharge the battery. A flat battery may also be a result of a fault in the vehicle's charging system.
  • Human Error - None of us are perfect. Leaving the headlights or interior lights on, or not closing the boot properly can all potentially flatten a vehicle's battery overnight.
  • Parasitic drain - This is caused by components in the vehicle which continue to operate after the engine has been turned off. The most common offenders are dashcams, alarm systems, or electronic rust prevention systems. These items can gradually wear a battery down over time.
  • Driving habits - If a vehicle is driven on a lot of small trips, the battery may not receive enough charge to recover the energy lost cranking the engine at the start of the journey. Lead-acid batteries also lose power gradually over time when not in use, so batteries in vehicles which are rarely driven will eventually end up going flat.
  • Old battery - Old batteries are simply not as good at holding their charge - so if a vehicle consistently won't start it is possible that the battery has reached the end of it's life. Lead-acid batteries last 42 months on average, so if a battery is beyond this age it is on borrowed time.

  If you've recently experienced a flat battery, it is important to have an expert investigate whether any problems exist with the vehicle's charging system before a new battery is fitted.

• Will going for a drive recharge a flat battery?

  Simply going for a drive will not provide enough charge to recharge a flat battery. Vehicle charging systems are designed to provide a 'surface charge' which is sufficient to maintain a healthy battery, but nowhere near enough to bring a flat battery back from the dead.
  
  The only way to recharge a flat battery is to use a proper multi-stage battery charger, with an amp rating high enough to restore the battery to peak performance. We recommend selecting a charger which is rated at 10% of the battery's Ah rating.
  
  For example, a Yuasa 68 MF has an Ah rating of 64. 10% of 64 = 6.4amps = Use a 6amp charger.

• Why do car batteries go flat over time?

  Almost all batteries have a natural tendency to go flat over time, especially when they're not in use. If you've got an old mobile phone stored in a draw at home, you'll notice it'll probably be flat the next time to try to turn it on - and it's the same story with the battery in your vehicle.
  
  Lead-acid batteries lose charge over time, and this problem is often made worse by the parasitic drain of electrical devices within the vehicle which continue to operate even whilst parked. For vehicles which are rarely driven, a battery maintainer or trickle charger should be used to prevent the battery from self-discharging and going flat.

• Do flat batteries affect fuel economy?

  Most of today's vehicles have 'smart charging' profiles which automatically disengage the charging system and stop charging the battery when it is near full capacity. Therefore, a vehicle fitted with a heavily discharged battery will place more load on the engine as the alternator remains engaged to recharge the battery. This will typically result in increased fuel usage.

• Are batteries with higher CCA ratings better?

  Batteries are typically rated using CCA - which is a test of how much current a fully charged battery can deliver for 30 seconds at a temperature of -18°C. Generally, the electrical system in your vehicle is designed to pull a fixed amount of current for each of the tasks it needs to perform - so batteries with a higher CCA will not start your vehicle faster or make it perform better.
  
  The CCA rating of a battery will gradually reduce with time, so batteries with higher CCA ratings do have the potential to last longer. However, other factors come into play here - including how well the battery has been built, the strength and thicknesses of the internal lead plates, and how much electrolyte it contains.

• Why did my battery only last a few years?

  Lead-acid batteries last 42 months on average - however this figure may be reduced or extended depending on a number of factors, including:

  • Whether the battery has been installed correctly.
  • If the battery chosen is suitable for the vehicle and driving application.
  • The climate in which the vehicle is driven.
  • The voltage which the battery is usually kept at.
  • Whether the vehicle has high or low parasitic drain when not in use.
  • How often the vehicle is used, and the length of the journeys.
  • Whether the battery and the vehicle itself have both been well maintained.

  Based on these factors, batteries fitted to vehicles which are used in hot climates, driven on short journeys, and rarely maintained would be expected to have a shorter life. Conversely, vehicles which are used in milder climates, driven further, and receive regular maintenance would typically have a longer life.