I had the same issue with my 2003 +8 and relocated a conventional battery to the rear, since then no issues. The battery location under the hood/bonnet is hot and very hard on the battery, and the Odyssey is of a delicate construction since it uses very thin plates to maximize starting ability (power) while occupying a smaller physical volume. This also reduces battery capacity (energy) - hence the need to constantly 'top up' this type of battery (very low reserve capacity). These batteries are little more than big capacitors - IMO.
