+1Vulcan:
The charger, not the battery, has control of how "huge" the load is. A modern alternator will supply current up to its rated maximum and no more.
As for outgassing, it depends entirely on the battery technology. Many modern AGM batteries are fully sealed and cannot outgas. Moreover, non-sealed batteries outgas WHENEVER they are charged. If you can't trust your vehicles venting arrangement during a manual recharge, you can't trust it during normal operation, either.
Get your problems properly sorted, then relax and enjoy your system as it was designed.