Should I remove the batteries from the boat when I charge them?

[KM7]

I have dual batteries and a battery switch. I store the boat in the driveway during the winter. I charge the batteries every 4 months or so using an automated step down charger. It can start at 15, 10 or 2 amps and will automatically adjust the current as the battery charges.

Should I remove the batteries when I charge them?
Why, and what is the source of the information?
Thank you

 

[Scott Danforth]

I would simply keep your battery switch on off, and charge one at a time at the terminals

 

[KD4UPL]

Why bother charging them? I leave mine in the boat all winter with the battery switch off. It always starts in the spring.

 

[Grub54891]

If the batteries are fully charged and disconnected when you put it to sleep, they should be fine in the spring. I disconnect the negatives to eliminate any parasitic draw. If the battery goes bad by spring, it didn't want to be a battery anymore anyway. As far as charging, leave them in place, why go through the trouble of messing around. Six years on one of my boats right now, we'll see in the spring if it held up.

 

[Scott Danforth]

lead acid batteries self discharge 5% per month.

 

[Grub54891]

lead acid batteries self discharge 5% per month.

Yes, I do charge them before startup in the spring for a day. Seems to not be an issue for me.

 

[Chris1956]

Leave them in the boat, battery switch off and trickle charge them every 2 months.

 

[jhebert]

I do not remove the ultra-high-purity lead-acid absorbent-glass-mat constructed batteries from my boat during winter storage. These batteries weight about 65-lbs each, and they are in an awkward location to install on or remove from the boat.

The reason I use ultra-high-purity lead is that lead-acid batteries made with ultra-high purity lead have extremely low self-discharge rates. The self-discharge rate decreases with ambient temperature. My boat sits in an unheated storage building all winter at a latitude above 45-degrees-North, and the lost charge from October to May is very small. There is no charging done during the storage period.

Note that the AGM construction is not related to low self-discharge rate. The low self-discharge rate is from use of ultra-high-purity lead in the construction.