Anyone else finding boat installations a nightmare for condensation on battery terminals?

Been running a 200Ah Fogstar Drift LiFePO4 bank on the boat for about 8 months now and the terminal corrosion is relentless. Smear them in petroleum jelly, come back a fortnight later and it's back. Worst over winter obviously but even now it's a pain.

Running a Victron SmartShunt and occasionally get dodgy readings that I'm pretty sure are down to a dodgy connection rather than anything else. Already torqued everything to spec.

Anyone found something that actually works long-term in a marine environment? Considered those anti-corrosion terminal spray cans but not sure if they're worth it or just marketing fluff.

@BazBurns the marine environment is genuinely brutal for this. One thing that made a real difference on my garden office install (admittedly not a boat, but similarly damp Suffolk air) was switching from petroleum jelly to proper dielectric grease — petroleum jelly actually has a relatively low dielectric strength and can wick moisture rather than repel it.

More importantly though, have you looked at terminal covers? Not just the rubber boots, but proper neoprene insulating boots that seal the whole lug. Combined with a small silica gel desiccant pack inside the battery compartment, you're attacking the moisture problem at source rather than just treating the symptom at the terminal.

Also worth checking your compartment ventilation — paradoxically, a well-ventilated space with controlled airflow stops the dew point cycling that causes condensation to keep reforming.

@BazBurns feel your pain on this one. Beyond the jelly, have you tried those anti-corrosion terminal washers/rings? They're impregnated with a vapour that inhibits oxidation and you just slip them over the posts before connecting. Combined with a proper dielectric grease rather than plain petroleum jelly, I found the interval between cleanups stretched considerably on a damp narrowboat install I helped with last year.

The other thing worth considering is whether your battery compartment has adequate ventilation to actually move the moist air rather than just letting it sit. Even LiFePO4 that doesn't off-gas like lead acid still suffers if it's essentially sat in a humid box. A small 12v computer fan on a timer running a few times daily made a noticeable difference. Cheap fix worth trying before anything else.

@BazBurns worth looking at whether your battery compartment has any ventilation at all - sounds counterintuitive but a completely sealed space actually makes condensation worse as there's nowhere for the moisture to go. A small louvre vent low down and another higher up creates passive airflow that dramatically reduces the damp sitting on everything.

Also on the Fogstar Drift specifically, have you got the terminals covered with neoprene boots? The rubber caps make a proper physical barrier rather than just relying on grease. Combined with @JimButler's suggestion about the washers you'd be giving yourself two layers of protection.

One other thing - are your cable lugs tinned copper or bare? Tinned holds up so much better in marine environments. Might be worth re-terminating if not.

@BazBurns been down exactly this rabbit hole on my own boat build. What finally cracked it for me was a combination of two things nobody mentions together: heat shrink ring terminals instead of bare copper lugs, and a small sachet of silica gel desiccant inside the battery box itself. The shrink-lined ones with the adhesive lining seal off that exposed copper completely, so you're not fighting a losing battle against the environment.

The desiccant sachets sound trivial but the difference was noticeable — swapped them out monthly initially, now quarterly. You can get the rechargeable tubs that you dry out in the oven, which suits the boat lifestyle rather than constantly buying sachets.

The petroleum jelly is fighting symptoms. Cutting off the moisture pathway to the terminals is the actual fix.