I wouldn't.
While it might work, and I doubt it, you'd have no way of controlling the charging of the battery. Are you doing a bulk charge or just trying to float the battery? You'd still need a charge controller, something to regulate how much power is going into the battery. Without that, I think you could overcharge the battery, with disasterous results.
I'll confess, I know just enough of the topic to encourage you not to try this hack, unless greater minds than mine hold forth.