On Board Charger Setup

[HHHIII]

I recently purchased a Lund Fisherman 1800. It was equipped with a 24 volt trolling motor, 3 bank charger and four batteries. Two marine deep cell batteories are connected to the trolling motor and are in the middle of the boat with the charger. I have two batteries in the back of the boat. One is a regular cranking battery and the second is a marine deep cell battery. In the back of the boat I have a Blue Sea switch which I think allows the selection of which battery is used to start the motor and which battery is charged by the motor. All my electronics are connected to the rear deep cell battery.

The previous owner has the two trolling batteries connected to two legs of the charger. The third leg of the charger is run to the back of the boat but is not connected. He explained that with the Blue Sea switch that the charger should not be connected to either of the back batteries. I would like to use the third leg of the charger if possible. This is the reason for my question.

I also had someone tell me that the two rear batteries should be the same type of batteries to be able to run the Blue Sea switch on the 1&2 setting. Is this correct? What is the proper way to use this Blue Sea switch?

I have learned a lot from this website and thanks in advance for your advice and help.

[walleye.bill]

The sea switch is really there for emergency purposes. If your cranking battery dies you have the option to manually connect them and pull power from your house battery. If you are talking about a battery switch, as long as you leave the switch in the OFF position you would be fine to hook the third leg of the charger to the house battery. I don't know what your running for a motor, but as long as it is not a Verado with power steering then you shouldn't have to ever worry about your starting battery if all your accessories are run off the house battery.

I have a similar setup, however I run a automatic relay charger and the manual switch. In this case both batteries should be the same. What it does is the battery switch is there for similar purpose, to have the ability to manually connect them for emergencies. The automatic relay allows me to charge both batteries with one leg of the charger and the motors alternator. The relay keeps batteries disconnected until it sees a charging rate either from your charger or motors alternator. It will then connect the batteries to charge both at one time until the charge is removed in which it then automatically disconnects them. I love the system.

I hope I helped and didn't just confuse the crap out of you.

[REW]

HH,
Pretty simple.
Run the charger to the switch. Put the switch in one position one day for charging the starting battery and put the switch in the other position for charging the house battery.

Really no big deal.

If you have used the main motor quite a bit, and have not used the accessories too much, then the main motor will likely keep the starting battery in pretty good shape. If so, just keep the switch in the house battery position and let the charger charge that battery any time that the on board charger is plugged in.

REW

[Mpower]

Originally Posted by REW

HH,
Pretty simple.
Run the charger to the switch. Put the switch in one position one day for charging the starting battery and put the switch in the other position for charging the house battery.

Really no big deal.

If you have used the main motor quite a bit, and have not used the accessories too much, then the main motor will likely keep the starting battery in pretty good shape. If so, just keep the switch in the house battery position and let the charger charge that battery any time that the on board charger is plugged in.

REW

can you clarify a bit...run the positive to the switch post, but where are you connecting the negative wire? And how is that better than connecting the charger directly to the battery posts?

[Burr]

I anticipate the Blue Sea switch is simply just a switch that allows you to turn it on - in effect making your starting battery and your house battery act as one battery with higher reserve capacity.

Or turn it off - completely separating your starting battery from your house battery.

In that case - you have some choices. I would consider hooking up the 3rd bank of your onboard charger to the house battery, and when plugging in the onboard charger turn the Blue Sea Switch off. That way, only the one battery will be provided charge with the onboard charger, and when it reaches a full state of charge, it will shut off.

The reason to not charge the batteries with the switch turned On is IF one of the two batteries goes bad, the charger will continue to send current and try to charge both batteries, in effect - cooking the good battery. You would be assured that when one battery goes bad, you will need to purchase two.

If you have good acess to the Blue Sea Switch - you can manually turn on or off when you feel it's benefitial. For example - If you are fishing a tournament, and your presentation is anchored, all day long. With livewells running to keep fish healthy, with sonars running all day, all this electrical load for 7 straight hours, and no charging from the main motor - then I would turn the switch to the off position at some point during the early day - to assure your starting battery retains enough charge to start the big motor and make weigh in cut-off time. I'd probably leave it in the On position for normal operation.

If you replaced the Blue Sea Switch with an automatic combiner - the combiner in effect turns the switch on when the big motor is running (combines them), and turns it off when the big motor is shut off (Separates them).

[walleye.bill]

Looks like a lot, but it's not. This is the automatic relay charger and switch with two batteries I currently run.

[HHHIII]

Thanks for the replies. My Blue Sea Switch is a little different from Walleye.Bill's switch. My switch has positions for 1,2,1&2 and off. Cranking battery is 1 and house battery is 2. Does this change any of your replies?

[Just One More Cast]

I had a guest switch on mine and if left with the two batteries connected it would drain the both dead in the garage. There's a reason for that if you Google it. I'd run the 3rd charger line to your rear accessory battery isolated from your boats charging system so the charging doesn't interfere with your sonar/GPS. Don't leave the 3rd leg of the charger disconnected because it will kill your charger prematurely.
I run a 36 volt on a 3 bank & a cheaper 2 bank on my start & accessory batteries. Run a heavy duty 110v multi-plug to both & plug in just one plug between trips. Works great & clearer electronics.

[Hot Runr Guy]

Originally Posted by Just One More Cast

I had a guest switch on mine and if left with the two batteries connected it would drain the both dead in the garage. There's a reason for that if you Google it.

One More,
I'm not finding any on-line references to the battery switch causing a drain, would you please post the link(s) so I can read what you saw?

Thanks, HRG

[walleye.bill]

The switch would not be what causes the drain. The only way it would drain is if you left the switch on connecting the batteries. Batteries naturally try to level out or maintain identical voltage so the fight each other until they are drained. That is the reason they came up with the idea of an automatic charging relay. Trust me, get the relay and do it right. You will not regret it and then go fishing and don't worry about batteries.