Battery charger

[Cruzin]

On my new to me 87-27 I have some questions regarding the function of the battery charger. My question is how does the charger work in relation to the battery selector switch? Which batteries are being charged relative to how the battery selection switch is switched? Is it possibly just wired to charge everything at once? I assume it is the original factory battery charger? Thanks for your assistance.
Dale

[Jim in TC]

I am going to go out on a limb here and suggest that the battery switch is connected to the output of the battery bank, with the charger not involved in that side of the circuitry. On our (factory installed electronics) SunCat charging begins as soon as shore power is plugged in (and the electric panel is on) and the charger automatically shifts charge modes depending on state of charge. So it will not overcharge the batteries even if left on. All this independent of the battery switch. I think so anyway...I usually have the switch on 'both' when charging since I am using some of the power to charge a radio and monitor voltage on a little accessory plug usb charger/voltmeter.

[brackish]

The 27 folks will probably give the best answer, but on my 23 it was also direct, in my case it did not even go through the AC panel even though there was a breaker marked "charger"  Both the charger and the alternator out from the little outboard go direct and not through the switch.   

[BobK]

I literally just installed a battery charger on my 27 this week.  Prior to this I was using a solar panel. The two battery charger (only 2 batteries) connects directly to the batteries, the 1-2 both,off switch has no affect on the charger.  I did wire the 110 volt side through a circuit breaker marked charger for safety and for the ability to turn the charger off when desired.
BobK

[wes]

Yes - a proper charger installation is direct to the batteries, therefore upstream of and unaffected by the battery selector switch.

Everyone should own a copy of Don Casey's "Sailboat Electrics Simplified" ($23 from Amazon). It answers almost every common question about batteries and the things connected to them. And it's an entertaining read - he's a funny guy.

Wes

[Cruzin]

Thanks everyone!  I appreciate your assistance!

Dale

[moonlight]

Not to stir the pot nor insert any controversy, but perhaps an "amendment"?
Best install is battery charger to battery switch - to each individual battery.  Thus, battery charger charges each battery without being "directly" connected, and independent of battery switch position.  SO, battery 1 output from charger to battery 1 input of switch, battery 2 the same.  Negatives to negative bus.  Thus the only thing you have on the battery is the cable to the switch, simplicity and less chance for confusion when swapping batteries which should happen more often than swapping chargers.
Alternative, in the power boat world (small bay boat fishing craft at least), is to in fact run each leg of the charger to each battery independently.
AND ALWAYS ALWAYS ALWAYS each source of power should be fused.  That means a fuse near the battery (somewhat avoided if you're attached to the switch with 12ga wire and it's 4ga or 2ga from there to the battery), as well as a fuse near the charger (sometimes intrinsic or built in).  Each (battery and charger, independently) are a "source" of power, each capable of overheating a wire, such overheating leads to a fire, such fire at least is self extinguishing (at the waterline).

[brackish]

Not to stir the pot nor insert any controversy, but perhaps an "amendment"?
Best install is battery charger to battery switch - to each individual battery.  Thus, battery charger charges each battery without being "directly" connected, and independent of battery switch position.  SO, battery 1 output from charger to battery 1 input of switch, battery 2 the same.  Negatives to negative bus.  Thus the only thing you have on the battery is the cable to the switch, simplicity and less chance for confusion when swapping batteries which should happen more often than swapping chargers.
Alternative, in the power boat world (small bay boat fishing craft at least), is to in fact run each leg of the charger to each battery independently.
AND ALWAYS ALWAYS ALWAYS each source of power should be fused.  That means a fuse near the battery (somewhat avoided if you're attached to the switch with 12ga wire and it's 4ga or 2ga from there to the battery), as well as a fuse near the charger (sometimes intrinsic or built in).  Each (battery and charger, independently) are a "source" of power, each capable of overheating a wire, such overheating leads to a fire, such fire at least is self extinguishing (at the waterline).

At the very least, that did stir the pot of confusion, at least for me.   I just installed an onboard charger, a Promariner 6 single bank.  I did extensive research prior to.  My intention was to downsize to a single large house battery since I no longer had a starting load.  All of the chargers I researched that were multi bank already had individual leads per bank, so why would a separate switch be necessary?  You are talking in terms of 12 ga., 4ga, 2ga., my charger and the multi banks of the same brand and per bank output have 16ga. connected to the ac and probably the same to the battery with all inputs fused individually.  2ga.? for DC input to a single 12V battery?  Another caveat, one that bothered me is that any alteration to the wiring of the charger AC in or DC to the batterie(s) would void the warranty on the charger.  That one bothered me as it meant I had to use their molded plug in to a GFCI protected outlet which I had not intended to do and will reinstall post warranty directly to the AC panel which is a much shorter and better protected path.

[moonlight]

Keep in mind that most of the vessels I service are much larger, have multiple inboard or outboard engines, and wiring to the battery switch(es) is often the shortest path to the then much larger wire that carries/controls house and starting loads.  Certainly on a simple single battery system, taking a single bank 6A charger directly to the battery is "simple".  Always keep in mind that regardless of chemistry (AGM, Flooded Lead Acid, Gel Cell) if you're working with any of those variants of Lead-Acid technology the charge acceptance rate is generally capped at 10% of the battery capacity.  SO if it's a 100Ah battery, a 10A charger.  If it's a 72Ah battery, a 6A charger.  Same for a 58Ah battery.
If you move away from Lead-Acid variants, a whole host of variables change...