Boat Battery Charger

[Angry Perch]

I need to install an on board charger in my new boat, but have never dealt with a battery selector switch, The batteries are wired parallel, and I believe the negatives are tied together, and the positives go through the switch. Do I use a 2 bank charger and hook to each battery as if they are independent, a 1 bank charger and charge with the selector switch on, or

[Skillet]

Yep, I'd do the two-bank charger and wire the pos and neg leads directly to each batt.  You won't need to mess with the switch at all.  Even if it is open and combining both batteries, the charger's individual circuits will only "see" the battery it is attached to.  If the selector switch is open, the current will flow between the batteries and you'll get a balanced charge. If the switch is closed, the smart charger (Guest was always my favorite brand on the walleye boats) will be better able to charge each battery individually.  Especially if one was significantly drawn down over the other.

If you're running any really heavy DC loads that the kicker or main can't keep up with (ie., a bowmount) and you want to fish two full days back-to-back, I'd get the 10 amp per circuit charger (20 amp total) at a minimum.  Otherwise, if its only purpose is a maintenance charge between trips, the 5/10 should be just fine.

Just my $.02

[Stein]

They probably aren't in parallel, both the positives and negatives would need to be directly tied to each other.  Most likely, one battery is for starting and the other for different loads or something along those lines.

I would get a 2 bank charger, Cabelas has house brands that go on sale frequently and have worked great for me.

[Angry Perch]

It's like parallel with an switchable positive. There are not separate house and starting batteries. You can choose where power comes from, but not where it goes to. If wired as drawn, the negative connection between batteries does not confuse the charger?

[Ridgeratt]

A ground is a ground. Just like in a car they ground to the frame. The only reason the hot side is separate is so they can be switched. Your car battery is grounded to engine block and bonded to the frame someplace near it

[Angry Perch]

A ground is a ground. Just like in a car they ground to the frame. The only reason the hot side is separate is so they can be switched. Your car battery is grounded to engine block and bonded to the frame someplace near it

It's good for a guy to get slapped upside the head with the obvious every once in a while!!! 

So if i were to wire it this way, and have the battery selector on both, would there be a problem?

[Angry Perch]

Yep, I'd do the two-bank charger and wire the pos and neg leads directly to each batt.  You won't need to mess with the switch at all.  Even if it is open and combining both batteries, the charger's individual circuits will only "see" the battery it is attached to.  If the selector switch is open, the current will flow between the batteries and you'll get a balanced charge. If the switch is closed, the smart charger (Guest was always my favorite brand on the walleye boats) will be better able to charge each battery individually.  Especially if one was significantly drawn down over the other.

If you're running any really heavy DC loads that the kicker or main can't keep up with (ie., a bowmount) and you want to fish two full days back-to-back, I'd get the 10 amp per circuit charger (20 amp total) at a minimum.  Otherwise, if its only purpose is a maintenance charge between trips, the 5/10 should be just fine.

Just my $.02

Hey buddy, your two cents is worth at least a nickel!

[Crunchy]

I mounted my charger and routed this to run an extension cord to.  Nice and neat.

[Bronson]

A ground is a ground. Just like in a car they ground to the frame. The only reason the hot side is separate is so they can be switched. Your car battery is grounded to engine block and bonded to the frame someplace near it

It's good for a guy to get slapped upside the head with the obvious every once in a while!!! 

So if i were to wire it this way, and have the battery selector on both, would there be a problem?

If I understand your question correctly, using the 1+2 or "both" option on your battery switch should only be used if youve drained one or both batteries and need as much power as possible to get your main started.  When you run your switch on "both" or 1+2 you are using power from both batteries and its not necessary.  Consider it an emergency use only option. 

If youre using power from both, youre draining power from both and have no backup.

[birddogdad]

there are several potential configurations for your system, this link should help you understand the most efficient way to charge based on your config.

i think the easiest way to say it is charging each battery if you can is best, even if you have switch or split deep cycle (troll) and crank sub systems.


https://www.impactbattery.com/blog/tutorials/how-to-charge-marine-and-rv-batteries-in-parallel/

hope this helps!

[Stein]

I would buy the two bank and charge with it in the off, 1 or 2, not "both" setting.  Wire the two red leads directly to the battery terminal (not to the switch or downstream from the switch.  The black one goes to any readily available black post, just make sure both batteries truly have their negatives tied together. 

When you put the switch in "both", they are connected in parallel and unless the batteries are exactly the same, one will be trying to charge the other all the time and it may interfere with the charger, but I'm not sure on the latter point.

A two bank charger is by far the best option.  Distant second would be a one bank charger wired downstream from the switch.  It would charge whatever battery was switched on at the time (1 or 2), again I would never run or charge in the "both" switch setting.  Distant third place would be to only charge one battery, but then you wouldn't be sure the other one was ready to go when needed.

That is very similar to how I have my boat wired, I always run on 1 and 2 just sits there fully charged waiting for me to need it.  A couple times a year I switch over to 2 just to check to make sure it will fire the motor, but then back to 1.  That battery should last almost forever as it sits on a battery tender and never gets used.

The 8A 2 bank charger is on sale for $80, 12 A is $100 and 20A is $120.  If I were running an electric trolling motor or otherwise was drawing it way down every time I would go with one of the bigger ones, but the smaller or mid sized is fine for normal applications where you are running sonar and downriggers and it sits plugged in overnight.

https://www.cabelas.com/product/CABELAS-PRO-SERIES-ON-BOARD-CHARGER/2416312.uts?productVariantId=4826592&WT.tsrc=PPC&WT.mc_id=GoogleProductAds&WT.z_mc_id1=04583803&rid=20&ds_rl=1252079&ds_rl=1252079&gclid=EAIaIQobChMIzILKvryz5gIVtRx9Ch2v4gi3EAQYASABEgL86_D_BwE&gclsrc=aw.ds

[Angry Perch]

Thanks for your help guys. I think I've got it all figured out.
Crunchy, I like the idea on that plug. A lot cleaner than having the cord hanging somewhere.

[Bill W]

how many batteries on your boat?  3?

[Ridgeratt]

Thanks for your help guys. I think I've got it all figured out.
Crunchy, I like the idea on that plug. A lot cleaner than having the cord hanging somewhere.

I would ask what it is plugged into. That's a female cord cap. If that is correct then he has built a cord with a pair of male ends. That makes an exposed hot set of blades on a cord. 

[Angry Perch]

Thanks for your help guys. I think I've got it all figured out.
Crunchy, I like the idea on that plug. A lot cleaner than having the cord hanging somewhere.

I would ask what it is plugged into. That's a female cord cap. If that is correct then he has built a cord with a pair of male ends. That makes an exposed hot set of blades on a cord. 

It's male under the cap.