The following article details information on where to find your battery, and how to jumpstart it.
As your truck battery is located on the under-floor area inside the cab area, if your truck battery runs low and will not start, there are jump-start positions under the bonnet. It is much easier to jump start from under the bonnet as opposed to accessing from the under-floor area.
Please refer to the video below on where and how to pop the bonnet and you will see where to attach your jumper leads.
These new engines still have a small draw on the battery when parked up, so if you are not going to use your motorhome for a month or more, please take it for a drive or start the engine in your driveway to keep things ticking over. If your motorhome is going into storage, it may pay to lock the battery up to a trickle charger.