I have a HAH and I know I can charge the battery by reving engine up in park to about 2500 rpm and see the charge indicator start and then backing down to about 2000 rpm to keep it charging.

Yes, it wastes fuel, but it will charge. It takes about 3 mins to charge my hah battery fully. I do this about once a month at night before putting the car away in the garage. Then, I hope to still see a full charge on the battery pack in the am. So far, I do. Its an 05 with 11k miles.

Perhaps this can be tried on your Civic as well.

Good luck

Tony