[Anderzip]

Can I trickle charge via the cigarette lighter (is it always on) or do I need to re-wire it?

[CraigB]

No you cant charge the battery via the power outlet/cigarette lighter...power out - not in.

In your situation I would use maintenance charger, CTEK are highly recommended CTEK MXS 5.0 (12V 5A) Battery Charger MXS5.0 | eBay

I use their Lithium model if I'm away for long periods