390DA batteries

[Jus Cruisin]

Ok, apparently you don't disconnect the batteries on these boats because once you do there'll be no power to drop the hatch or lift it in the spring or during the winter for maintenance. Just turn off the switches and that's it? I just don't want to end up with 5 dead batteries in the spring.

 

[Fred]

I have always switched off all main breakers in the bilge except for 3 of them. The 2 battery charger outputs to facilitate charging and the upper most right side breaker which powers the helm so the engine lid can be raised and lowered.

 

[Fred]

You can also raise the hatch from an external battery through the cigarette lighter at the helm.

 

[Shenanigans77]

I disconnect all my batteries then hook a jumper box to my forward eim under the dash and drop the hatch. Reverse in the spring

 

[Creekwood]

You can also raise the hatch from an external battery through the cigarette lighter at the helm.

This is the answer^^^

Disconnect the positive lead on all batteries over winter, and use a backfeed through the cigarette lighter at the helm to power the hatch. This is what I made up to do it. Way too long wires since one battery bank is under a cockpit seat about 5 ft from the 12v port.

 

[Jus Cruisin]

I'm going to head down to the boat tomorrow and do some investigating and check out where that 12 volt cigarette lighter is. I think that'll be what I'll do.

 

[techmitch]

This is the answer^^^

Disconnect the positive lead on all batteries over winter, and use a backfeed through the cigarette lighter at the helm to power the hatch. This is what I made up to do it. Way too long wires since one battery bank is under a cockpit seat about 5 ft from the 12v port.
View attachment 114690

Always, Always disconnect the negative battery cable first.

 

[Creekwood]

Always, Always disconnect the negative battery cable first.

Why is that? I leave the negatives attached all year round, except when I periodically take them off to clean up posts. Also, my marina does the final battery disconnnect each winter after they winterize the engines, and they only ever disconnect the positive leads.

 

[techmitch]

Why is that? I leave the negatives attached all year round, except when I periodically take them off to clean up posts. Also, my marina does the final battery disconnnect each winter after they winterize the engines, and they only ever disconnect the positive leads.

Your marina should know better.
Here are just a few reasons.
https://www.motortrend.com/how-to/which-battery-cable-should-be-removed-first-but-installed-last/
Same with jumper cables BTW.

https://www.popularmechanics.com/cars/how-to/a1454/4213127/

More importantly is that electronics don't like being positive side switched off.

 

[Creekwood]

Your marina should know better.
Here are just a few reasons.
https://www.motortrend.com/how-to/which-battery-cable-should-be-removed-first-but-installed-last/
Same with jumper cables BTW.

https://www.popularmechanics.com/cars/how-to/a1454/4213127/

More importantly is that electronics don't like being positive side switched off.

I can totally understand that on a car battery (and that is what I do) where everything metal is likely a ground.

And I also know that with battery jumper cables the negative cable is never direct connected to the battery, its connected to a ground as far from the battery as possible to reduce risk of sparks igniting hydrogen gas produced during charging or the boost itself. Its also smart in case you drop the positive clamp onto the car body metal while the negative is still connected.

Less so on a boat where nothing near the batteries (other than the negative post and cables) is connected to ground and the "body" is fiberglass. And if a wrench contact with the negative post is a risk taking positive off first, its the same risk starting with the other side.

So while what you say is 100% true with cars/trucks, its less of a concern on boats. So my marina mechanics (which are all properly certified Mercury and/or Volvo techs I think know what they are doing by disconnecting the positive sides for winter storage. B

There is nothing on when they disconnect the cables (and when I reconnect in spring). Battery switches are off, chargers not on, nor shorepower. Bilge pumps I guess are connected, but they won't be running either.

Anyway, good advice on sequencing. And when I think about it, the negative side would probably be easier (no extra connections like invertor cables on the negative side), so I will ask them about it next spring.

 

[Jus Cruisin]

So, I was reading the owners manual today and and made it to the Electrical section. Battery disconnect sequence. Here you go. Positive first.

 

[techmitch]

I still disagree. That must be a misprint.