The gas you cannot smell
Wikipedia’s hydrogen article: colorless, odorless, flammable. Flooded batteries make hydrogen especially when a charger or a jump is driving current into a discharged pack. 33 CFR 183.420 requires a way for that gas to leave the boat. Jumping inside a closed console, with the hatch down and a spark at the post, is the opposite of that design. Open the well. Let it air. Then talk about cables.
Jumping is not a diagnosis
A boat that needs a jump every Saturday has a charging, parasitic, or end-of-life problem. Battery University’s charging article is about finishing a charge in stages, not about a weekly boost. We would rather test and replace than keep you in a ritual at the ramp.
Lead-to-lead, chemistry-to-chemistry
Jumping a lithium pack from a flooded truck, or the reverse, is a voltage and BMS story we do not improvise at the water. If the boat is lithium, follow the module maker’s jump rules or do not jump. If both are flooded, use heavy cables, last connection away from the battery, and keep sparks off the well.
Rotten-egg smell means stop
That odor is hydrogen sulfide, not hydrogen. Stop charging, ventilate, and do not jump a pack that is already gassing hard. The well is not a place to smoke or to drop a wrench across posts.
Better than a jump
Call us to the lift or trailer in St. Petersburg or Tampa. A rested voltage, a charger check, and a replacement if the pack is done will beat another Saturday with jumper cables in the cockpit.
After the engine starts
If a jump got you home, the next step is a rest and a test, not another week of jumps. We would rather see the boat on the lift the next morning. A flooded pack that gassed hard during the jump needs the well aired and a charger check so the next start is not in a closed box full of hydrogen.
Sources
- Wikipedia — Hydrogen (odorless, flammable)
- 33 CFR § 183.420 — Batteries (Cornell LII)
- Wikipedia — Hydrogen sulfide (rotten-egg odor)
- Battery University BU-403 — Charging Lead Acid
If this is the job on your boat, see how we replace batteries at the boat. We come to you — Florida towns and counties.