Quote:
Originally Posted by aab203
I noticed this warning (the power save one) for the first time today. I assumed it was because I do short journeys 95% of the time. Does this mean I am at risk of the car not starting then? That is a little disconcerting if so.
|
You are very much at risk
Short journeys are a killer on any car battery on any car.
The effect of the starter motor load plus the entire vehicle electrics cannot be sufficiently compensated by the alternator due to the short charging times available.
As a rule of thumb, you need around 15 minutes to replace the charge in the battery that was used to start the car. Very approximate, as this depends on engine temperature (cold start requires much more power than warm start) and on the total electrical load in the vehicle (on cold wet winters days with demisters running, wipers front and rear, heating fans running, lights on, etc - this all reduces the available reserve charge for the battery).
I would recommend you get into the habit of connecting an intelligent charger once a week to ensure your battery has sufficient reserve capacity to see you through your daily drives.
If you do not have the ability to do so because e.g. you park on the street, then aim for a 30min to 1 hour drive every weekend to top up the battery.
Whilst I tend to do 80% 30min drives in my MY2009 XC90, I know my battery is the original now 8 year old battery, and I give it a top up charge in my garage every now and then - around once a month - just to be sure. I use a CTEK charger, they are one of the best connect-and-forget chargers on the market, and also support the AGM type batteries in the new XC90s. I connect mine to the convenient 12V power outlet in the boot space.
Whilst I only have a 5A charger, as I only top up my battery every now and then, running 5A for 10 hours overnight will put 50Ah back into my 90Ah battery, which is sufficient to bring it to full charge
The newer XC90s use 80Ah or 95Ah batteries, so a 5A CTEK charger is sufficient for overnight use. Otherwise choose a 10A charger if you wish to top up the battery faster.
Remember too that the modern XC90 with start-stop has 2 batteries: an auxiliary battery provides the extended power for the start-stop function. The auxiliary battery is however only 10Ah.