Yikes, I'll stay away from non-ventilated sealant. My intent was to place it only on the posts and terminals, but I'm going to scrap the idea completely. I haven't done anything in regards to the battery project but price components and tools. I'll put the submersible car project on indefinite hiatus.
"Make sure the bend radius of the soldered part does not create a shear shelf and you are fine." Sounds like this is for direct terminal to cable connections. I don't understand what a shear shelf is in this context--probably squishing of the cable or avoiding kinks or too tight of a bend in the cable.
"You would want a hydraulically crimped brass marine type fitting" I'm having trouble finding any brass lug rings (heavy wall or non-heavy wall, the lowest gauge I've found is 8 AWG, way too small for this application). All I'm finding are tinned copper heavy wall lug rings for 4 AWG and larger diameters, unfortunately.
Found some expensive solid brass terminals (for non-lug ring connection):
http://www.amazon.com/Maxxlink-FLEXIbras...attery+terminal
http://www.amazon.com/ROCKFORD-FOSGATE-P...attery+terminal
And one inexpensive all-brass terminal for non lug-ring installation:
http://www.amazon.com/Gold-Brass-Battery...attery+terminal
Lead-plated brass, for lug-ring type connections (I'm seeing multiple products that are tinned as well):
http://www.amazon.com/Pico-Positive-Nega...attery+terminal
Sierra Marine's solid brass terminals have a problem with the bolts used, apparently:
http://www.amazon.com/Sierra-International-BT44470-Negative-Terminal/dp/B001PRVX08
These are brass finished (doesn't say what the internal material is; if it's just a finish, I'd guess it's lead), no tinning, no lead plating, and are lug-ring type; they are not referred to as marine terminals; neither of the two entries below have any reviews available:
http://www.oreillyauto.com/site/c/detail...5&ppt=C0005
It appears to be the same product from here:
https://tinnedmarinewire.com/wire/index.php?main_page=product_info&cPath=7&products_id=99
"brake motor against a running engine" I don't know what that is, so no, I'm not intending to.
"unless you are using an inverter or winch or other attachment #2 is way overkill" I have a small Maxx inverter I use for my laptop and dye sublimination printer; the present battery cables didn't seem to cause any issue with it. I've seen some accessories like an air pump run from the DC power socket, other than that I can't think of anything besides regular starts and engine use.
"If you are experiencing dimming lights or a redux in a blower its either due to a reduction in RPM, belt slippage, a defect in the alternator or a circuit issue creating resistance. The power steering is a mechanical function and not related to the vehicles electrical system." Yep, belt slippage. Squeeks like crazy and is a high priority in need of replacement along with the battery project, fluid changes, the muffler needing reattachment, and the other timing belt and a third belt that goes to other stuff needing replacement. Glad the alternator isn't failing at least.