Marine "start" battery - best way to maintain?

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Batman

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#281068 28-Jan-2021 09:33

Say you have a marine toy that you use once in a while -

What do you do with the battery?

Disconnect?

Keep it charged up?

Keep it at 50% like lithium ion battery?

Sorry I'm very ignorant on this topic

nedkelly

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#2643386 28-Jan-2021 09:42

Depends what you mean by once in a while.

My family has a launch that we use a number of times a year, though not as much in winter obviously.

We have a proper Marine grade start battery (or could be two, I cant recall) and then a house battery for everything else, periodically we will connect a battery charger to the batteries and then to shore power from the marina to top them up, and obviously start the boat too if not being used for a period of time to give it a run which also charges the batteries by alternator.

But not everyone does this, most marine vessels have a disconnect switch which completely isolates the battery from the boat when its not in use, so that should be ok as that will kill any trickle of power being taken from the battery when not in use unless you have something bypassing the battery switch.

Scott3

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#2643389 28-Jan-2021 09:49

Lead acid batteries are best maintained at a high state of charge.

Most trailer boats have isolation switches and typically have the batteries isolated in storage. If you do this and use the toy every 3 months or so the battery should do well.

Next step better would be to put a smart charger on it. These are designed to be left on and to keep the battery maintained at a high state of charge.

Mine is ctek brand.

If you don't want to leave it connected, charging when putting the boat into storage, isolating the batter, and topping up every 3 months or so should be fine.

Fred99

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#2643393 28-Jan-2021 09:56

Keep it charged.

If it's a typical car battery size (>40AH), then a small 5W solar panel is probably okay to maintain without running through a solar charge controller.

"Marine grade" is basically just robust, possibly AGM, built to take vibration/shock. For charging treat it the same as a car battery. They do not like being discharged to 50% - it'll kill them. They also don't like being over-charged, so if you connect a 50W solar panel direct, it'll kill the battery fast.

fearandloathing

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#2643399 28-Jan-2021 10:09

I use one of these to maintain a battery for a motorbike I don't use often.

Boyd Motorcycles - MOTOBATT CHARGER FAT BOY 12v 2.0A (Lead Acid/AGM/Lithium) - Motorcycle Parts - MOTOBATT

Batman

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#2643408 28-Jan-2021 10:36

Ok got a ctek already

Cheers