Using shore power to keep batteries charged

Flytrade

Active Member
Feb 20, 2018
302
Bradenton, FL
Boat Info
2006 320 Sundancer
Engines
Twin 6.2L Mercruiser
I use my boat at least every other week. However, I have been told it's also a good idea to keep the batteries charged by keeping the boat plugged into shore power. Since I use the boat so often, is this really needed?

When I do use shore power I turn on the converter. Do I need to have the batteries turned on as well, or does the system charge the batteries directly?
 
The right charger will trickle charge them so they are just right. They don’t need to be on when you are not on the boat to get charged
 
If you are making use of a house bank while on the hook, then making a short ride back to the slip, then your house bank is likely getting put away low. Not good for the life of the battery(s). A shore charger will do what the alternator cant (and is not really designed to do) between outings.
 
I always kept my batteries plugged in to shorepower. But then I had confidence that my multistage charger would switch to a trickle charge when the batteries were full. The added benefit of keeping them plugged in is if you had left something on they wouldn't drain. Likewise if the bilge pump kicked on that wouldn't drain the batteries either.

On the latter, we had a sailboat partially sink in our harbor because it had a small fresh water leak (connected to a dock faucet) and the boat wasn't connected to shore power. After a while the batteries finally gave out. That's the other tip always disconnect the fresh water before leaving the boat.
 
My boat stays plugged in, with two smart chargers on keeping the batteries topped off. I also leave the AC on. Boat is ready to go and nice and cool down below.

Jaybeaux
 
Also, If your leaving boat plugged in and trickle charging make sure to check battery fluid level at least every 60 days and top of with distilled water. I have seen batteries dry out from frequent charging.

All the best
 
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Thanks for all your great replies.
Two other things to keep in mind. You likely have some electronics and music systems on your boat that place constant small loads on your batteries gradually depleting them. When you start your engine, your alternator will work overtime to keep the batteries up causing extra wear and eventually maintenance expense. It is probably cost effective to keep them topped off if you have the correct charger and battery combination. Charging is likely cheaper than maintenance expense.
 
This keeps your batteries in good shape. Just make sure you keep a good eye on the water levels in your batteries. Distilled water only BTW
 

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