Xc60 my19 - last started the car 4 months ago
 

It will be four months in April since I last started my car as I am away abroad. The car is showing in ‘offline’ mode to ‘save battery’. Would the car start if I manually start the car upon my return. I am concerned because it is parked in a very tight garage with absolutely no room whatsoever to jump start the car. Thanks in advance, as always, for any information.

I have a jump starter the size of an iPhone (made by AntiGravity).

Buy one of those as I doubt it will start easily.

If you need to jump start your car the positive and negative connections are easily accessed under the bonnet from front of the car. Providing you can unlock it and get in to open the bonnet.

Sorry, my question is more directed (or should have been directed) towards the battery side of things. I am wondering would the battery be discharged (it hasn’t been started in 4 months) to a level that it wouldn’t be possible to start the car with out jump starting it.

You must jump from the provided connections in the engine bay (there's a copper bar for the positive and chassis ground can be anything). Do not try to jump directly to the battery terminals; apparently there's a squib designed to isolate the battery in a severe crash.

There is no room whatsoever to access the front of the car.

Fell a tree on the garage roof and claim on the insurance. Make sure you squish it properly though. :grn-wacky:




Hold on though, you may not have a convenient tree.

In which case you will just have to find a way to get a booster pack up front and attached to the clamps. Don’t despair though, because there’s a slight chance that it may just start no bother.

Another alternative is that if the main battery is in the boot, remove it and get it charged, replace and start. That may, from your description, be the most sensible.

Yes, likely it won't start.

Modern cars always use some power when off for alarm, central locking, keyless entry, trunk opening sensor, oncall, etc.

If going away for a long period of time, consider fitting an intelligent charge before you go (via connections under bonnet, or the battery in the rear) that keeps the battery topped up for the duration.

Or, at the very least, charge the battery fully with a charger overnight (or longer) a few days before you depart. This ensures the battery is at maximum capacity before you leave. I do this before I go away, purely for reliability reasons.

Or if you have done none of the above, and are already away, and cannot access the front of the car, and the battery is flat, then you have the following options:
1. roll the car out of the parking space and connect a battery charger to the charging points under the bonnet, or
2. open the tailgate and connect an intelligent battery charger to the battery under the boot floor (see notes below). Reduce the risk of confusion by connecting the negative charger cable to the vehicle body (and reduce the risk of explosion due to hydrogen gasses being vented during charging)

Always connect a charger with the charger turned off. Turn charger on once connected. This simply reduces the spark risk and reduces explosion risk if any vented hydrogen gasses are still present.

The Owners Manual for a MY19 XC90 clearly states many times that you MUST NOT connect a battery charger or battery booster to any connection other than the supplied charging connections in the engine bay.
This is to ensure the battery monitoring circuits and start-stop function do not get confused.

HOWEVER it also states that the system will be "temporarily" confused. So in an emergency you can charge the starter battery in the boot/cargo area, and charge overnight, and accept any temporary confusion that may result.

You should invest in an intelligent battery charger. I use a CTEK MX5, which is the same model supplied with Ferraries, Porsches, and other Supercars that often sit all winter, never being driven. And left connected, it keeps the battery topped up and ready for use, and avoids all those issues that occur when cars are not driven for a long time.
If you maintain your battery with an external battery charger regularly, you will reduce the risk of flat battery and extend the operating life of the car battery by a significant amount.
I just visited the CTEK website, and they have a brilliant little device: the CTEK CTX Battery Sense. Fantastic for those that don't drive much. My car is often sitting for a week or more, not driven. I'm going to buy one!

Some Extracts from the XC90 MY19 Owner's Manual
I highlighted some important bits for you.

Charging points
When connecting an external starter battery or battery charger, use the car's charging points in the engine compartment.
The battery terminals on the car's starter battery in the luggage/cargo area must not be used.
During charging, both the starter battery and the support battery are charged.

IMPORTANT
When charging the starter battery and the support battery, only use a modern battery charger with controlled charging voltage. Fast charging function must not be used since it may damage the battery

IMPORTANT
If the following instruction is not observed then the Start/stop function may temporarily cease to work after the connection of an external battery or battery charger:
• The negative battery terminal on the car's starter battery must never be used for connecting an external starter battery or battery charger – only the car's negative charging point may be used as the grounding point.

IMPORTANT
If the following instruction is not observed then the energy saving function for infotainment may be temporarily disengaged, and/or the message in the driver display about the starter battery's state of charge may be temporarily inapplicable, following the connection of an external starter battery or battery
charger:
• The negative battery terminal on the car's starter battery must never be used for connecting an external starter battery or battery charger - only the car's negative charging point may be used as the grounding point.

NOTE
If the starter battery has been discharged so much that the car has no normal electrical functions and the engine is then jump-started
with an external battery or a battery charger, the Start/stop function may continue to be activated. If the Start/stop function then autostops the engine shortly afterwards, there is a great risk that engine auto-start will fail due to insufficient battery capacity, because the battery has not had the time to recharge.
If the car has been jump-started, or if there is insufficient time to charge the battery with a battery charger, the Start/stop function is temporarily deactivated until the battery has been recharged by the car. In an outside temperature of approx. +15 °C (approx. 60 °F), the battery needs to be charged for at least 1 hour by the car. In a lower outside temperature, the charging time may increase to 3–4 hours. The recommendation is to charge the battery using an external battery charger.

NOTE
The life of the battery is shortened if it becomes discharged repeatedly.
The life of the battery is affected by several factors, including driving conditions and climate. Battery starting capacity decreases gradually with time and therefore needs to be recharged if the car is not used for a longer time or when it is only driven short distances. Extreme cold further limits starting capacity.
To maintain the battery in good condition, at least 15 minutes of driving/week is recommended or that the battery is connected to a battery charger with automatic trickle charging.
A battery that is kept fully charged has a maximum service life.

Just bern away for 6 weeks with car left out in the drive. Started first time.

Just a thought, but you can probably trickle charge if necessary using the car’s 12v accessory socket. Your main battery is likely to have enough power to energise the relay to connect it to the rest of the electrical network.

To be honest though you might be surprised. The main starter battery has an enormous capacity and could be fine. I’ve left a car for three months before and had no problems at all, and that had a huge diesel engine to start.