When you surface in a diesel sub & fire up the diesels
three most important things to do:

1. Post a lookout or 3

2. Pump up your high pressure air tanks.

3. Fast charge your batteries

Lead acid will take this punishment (with gassing). Lithium blows up

If you don't get jumped, float charge is OK. You may now top up the lithium batteries over 6 hours. By then, daylight is coming. Dive. You can then send guy with acid burns on his clothing, to top up the lead acid batteries with distilled water. Can't do a dammed thing with lithium, except replace a dud cell