Battery Chargers

[smullis1961]

Source of the post

Source of the post.... Let's say you have 20A of typical loads on the house side while you're using the boat (at the dock, plugged into shore power). If you had a 30A three-bank charger to feed the house and two starting batteries, the house battery would actually be DISCHARGING the whole time, while there was a bunch of unused capacity tied to the starting batteries (because there's virtually no loads on them and you're just topping them up or replenishing what might be used from a bilge pump)....

I'm not quite following. Most good chargers these days will throw full output to any one bank at a time when needed. With a ProNautic 30 amp charger for example, it will direct full output (30 amps) to the house bank if the engine batteries are already topped up which is pretty typical as they're usually already at full charge after a run. So very little needed from the charger at the dock for the engine batteries, maybe a float charge at best but certainly not 10 amps, at least not for very long at all. With only two banks on board, the third output leg from the charger can maintain the generator battery at peak charge. Even with that, the output to the engines and genny would be minimum, leaving plenty for the house bank. Of course more is better in terms of keeping up with consumption at the dock but power management is key no matter how big the charger is.

Thank you Viper for all the information, deeply appreciated.

[smullis1961]

Thank you all for all the wonderful information. It is deeply appreciated and helps me to understand more clearly what I need to supply my boat with the correct charger for my needs.
Steve

[km1125]

Source of the post BTW, I'm not a fan of a NOCO on a boat. They're not made for that IMO.

Why do you say that? They are marine-rated chargers and are fully waterproof, unlike many others. May not fit the OP's application but certainly would be appropriate in the right situation.

[Viper]

I am not a fan of anything potentially being installed in an engine compartment that incorporates an AC plug for one. I know you can cut it off to wire direct but that's if you're in the know, most aren't and would simply install an AC outlet which is a no no, I've seen this so many times. I'm also not a fan of having harness plugs in the charge lines, just another possibility for poor connections, corrosion, overloading, overheating, etc. And unless they've changed recently, there's no way I would use the ring terminals that come with the unit that they expect you to hook up direct to the battery terminals. Poor quality IMO, they're coated but if I recall, they're copper coated which is a no no and should be tinned for marine applications. You'll get the green death growing on them otherwise in a very short time. There's also poor reviews on that very topic with both the connectors and the alligator clips when just maintaining a charge at home let alone a permanent solution requiring full output on a regular basis. Don't know why they would consider these design features for permanent marine installations IMO. It's like they started off with an idea for one need then simply made a couple of tweaks and put the word "Marine" in there without reviewing the system as a whole. Otherwise they have some great charging features but they really need to revisit some basic stuff for permanent installations in a marine application. They're great for maintaining my lawnmower battery over the winter though

Just my opinion km, I'm sure a lot of people like them and so do I for other uses but not this one.