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I have a boat lift that is powered by 2 - 12V flooded batteries in series for 24V. The battery bank powers my lift up and down in order go get my boat in and out of the water. When I am operating the lift, do I need to unplug the charger or can I leave it plugged in? Also, any guidance on things to consider when deciding between a 5 A and 8A version?
I leave mine plugged in.
Your consideration in choosing size is charging your batteries at the correct c rating.
Too slow is just as bad as too fast with lead acid.
Yes, you leave the charger plugged in - that's the idea.
To choose the correct model/ max. current rating, it would be necessary to know your battery-capacity, -chemistry, -technology and typical use-case. Assuming a standard flooded lead-acid battery is given, recommended charge current will be 0.1 - 0.5 C.
That means, if you're charging a 70Ah battery, a current of 7-35A is recommended (during bulk stage). Generally, these information is best taken from the manufacturer/ battery-manual.
Flooded lead-acid batteries are not very critical about exceeding max. charge-current as long as max. voltage is strictly kept below the technology-specific limit.
Concerning the IP67 series, I'd go with the 24V/12A model, beside you're using a really small battery and don't mind about longer charge-cycles. Max. current can be limited to a lower value in the chargers configuration.
Just a hint - when wiring 2x 12V batteries in series, their capacity does NOT double (but voltage does).
++umgfoin.
