Originally Posted by LakeSuperiorGeezer
I always float my lead acid batteries, whether deep cycle of starter batteries when there is infrequent use. Here is a web site that explains: How Does A Float Charger Work?
If you like that and are comfortable, then it is fine, but PLEASE do check on them frequently! I have seen far to many failures of chargers, all types and brands, to leave batteries unattended and on smart of "float" chargers. I simply won't do it to my own batteries and don't and still get above average life out of them. In the cold North we simply don't need to leave them constantly plugged in if topped up and disconnected.
In hot climates it can be a necessity due to self discharge as this accelerates in warmer temps and drastically slows in cold temps..
Most all boat yards up here specifically ban this practice in the winter, if batts are left on-board, and also stipulate that the batts must be left 100% disconnected from the vessel.
Some battery manufacturers also specifically advise against it, such as Lifeline.
Not all chargers behave the same or charge the same way. Some that claim float or smart provide a constant current and some pulse it ON/OFF based on voltage. The higher the float voltage setting the more often the current will be flowing in a pulsed charger..
If battery chargers were more reliable I may not have such an issue with it but I just see far to many failures and the resulting destroyed battery banks. With cold stored batteries I see leaving them plugged in and unattended akin to fogging your cars engine every time you shut it off. Not really necessary..
The other side is we have many unscrupulous manufacturers claiming "smart charging" selling pure unadulterated JUNK that is nothing of the "smart" sort...
This charger ruined a customers $1400.00 bank of NEW gel batteries charging them at over 16V on the GEL setting.... Smart? Hardly.??
Schumacher Ship n Shore Over Charging - YouTube
In a perfect world a proper float algorithm is fine but we just don't live in a perfect world. Battery chargers remain one of the most unreliable devices I see on boats. Please use them carefully...