Charging Question for The Electrical Engineers On This Forum

[hotajax]

Dual batteries with conventional lead plate design. They can be run in combination, or selectively, meaning I can be using battery #1 OR battery #2. When using a battery charger, is it best to charge them individually with the master switch off? Or, is it best to charge them in combination with the master switch turned to both? I suspect that if the master switch is turned to "Both", then there will be some voltage leak throughout the boat's circuitry. What say the experts?

As an aside, in what situation, if any, would it be preferable to have both batteries turned on? Thank you. Hot Ajax

 

[everwhom]

Re: Charging Question for The Electrical Engineers On This F

You have a single motor right?

So the answer depends on how the batteries and charger are wired. If your charger is a 2-bank charger it may already be wired to charge both batteries simultaneously. Do you have 1 or 2 battery switches? (i.e. one for you motor and one for your lights & electronics, or do your motor and accessories run through a single switch?)

 

[DennisG01]

Re: Charging Question for The Electrical Engineers On This F

If wired properly, a battery charger is connected directly to the batteries. Meaning, the battery switch has nothing to do with charging. You should be able to charge your batteries with the battery switch set to OFF. Note that while it's best to have the charger leads go directly to the battery, the charger leads could connect to the batteries via the #1 and #2 post of the battery switch. This is essentially the same thing as connecting directly to the battery - although direct to the battery is still preferred.

BOTH can be used to start an engine if both batteries are a little weak by combining them together. You can also allow the engine to charge both batteries at the same time - although personally, I like to let the engine charge one battery at a time as opposed to splitting it's charging juice.

 

[SkunkBoat]

Re: Charging Question for The Electrical Engineers On This F

I would add that you would not want to charge them with the switch on BOTH. That effectively makes them one battery. Therefore, your charger will not be able to charge them based on the need of each.
The only time you should have the switch on BOTH is when you have 2 low batteries and you need to start your motor.

Whether or not you have an isolator or VSR also is a factor.

 

[RTNEPTUNE]

Re: Charging Question for The Electrical Engineers On This F

This is how the system should be set up . If it is not , rewire it so that it is .

1. Two batteries requires a dual bank charger . if you use a single bank charger on both batteries you may overdraw the charger and it will be damaged
2. Hook the dual bank charger directly to the batteries . This isolates the charging system from the battery switch .
3. Hook up your batteries 1 and 2 positive post to post # 1 and # 2 on the battery switch .
4. hook up the common or " engine" battery switch post to the engine battery cable .

I would never run the engine in the " both " switch position , only use this to start the engine in emergency situations when you don't have enough charge on one battery to turn over the engine . once the engine starts turn the switch to " 1" or "2" but never to off . If the batteries are low and you run the engine in " both " you may over draw amperage from your engines
alternator and burn it up .