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My brother recently purchased a boat, it has two batteries up front for the fish finder and trolling motor, connected in parrallel and one in the back for starting the boat. They are separate circuits and have inline charging/maintainer connections. My question, is there a way to make them one circuit for charging?
You can but I would not recommend it. Mainly you are going to need to charge the trolling battery's and you can do that with one connection charging both battery's at the same time. I would not want to add the third onto that same circuit because you could over load the charger and if on cranking battery is not going to need much charge and you could burn it up because charger is sensing the need for high amps at the front. Those 2 up front would equalize as they charge. Hope this makes sense.
It does actually, I have some understanding when it comes to circuits just not with charging multiple batteries.
Question, when you say it has charging connections, does I have connections previous owner installed to hook a portable charger to or connections for a onboard charger they removed?
They are the kind that a battery maintainer would hook up to and the maintainers look like nothing more than bulky wall chargers. I own a battery maintainer that would be more than adequate to replace these as it is a higher quality.
Our plan is to add in an onboard charger for ease of use and to simplify things, but that'll come as a later upgrade.
Here is the route I would take. When done fish for the day I would start with charging the trolling batteries. Once they are charged I would hook to the cranking battery. Cranking should just need minimal charge since motor should be doing some charging while running. If you have a multi meter you can always check charge before and after charging. With the maintainer I would disconnect it when done charging. I have found even with high quality maintainers they will keep a slight charge going and not completely shut off thus over charging your battery's over a period of time.
You did not mention this as an issue, but normally the depth finder is not run off the TM batteries. In many cases the TM will cause interference with the DF. If you are not having problems I wound not worry about it, but just a heads up in case you see some interference on the DF.
Thanyou, this is very helpful advice. I will make a checklist to make sure that this charge order is followed as my memory is not the best after a long day on the water.
Do you mean the TM will cause reading errors on the DF when they are running from the same source? If it is hooked up to the TM battery I will more than likely leave it that way. I'm hesitant about running the DF or any other units off of the main starting battery. Learned it the hard way and was stranded on a lake with no power.
On some units, not all, when hooked to the trolling battery they will pick up some interference when trolling motor is running. But not all units are affected. If you don't see it I would just leave it alone. I could be verticals lines running through the screen when you turn motor on. Normally you would not see a difference in depth reading more like static in your radio showing on the screen.