Another battery switch/TM question

[flagator1]

Great board and thanks in advance for your answers.

Problem: I have a 30 lb thrust Minnkota bow mount on a 18 ft Crestliner and it is killing my batteries in a half day trip.

Facts: I am running two 27 group deep cycle batteries (less then one year of age) wired directly to the TM and a seperate starting battery for a 2002 90 hp Johnson. I run a Garmin 172 GPS and an Ealge 320 fishfinder on the bow and duplicate this setup at the wheel. My Perko switch has an OFF, 1 (starting battery), All, and 2 (TM battery) settings. I charge this system with a 15 amp onboard charger. The other day I started the boat on the # 1 Perko switch setting and then set it over to the # 2 setting for the rest of the morning. Point of note, my boats voltage meter is no longer reading 14.5 when I am running the boat like it used to a few weeks ago.

Questions: Why at around one PM, after cranking the boat to move it from spot to spot x6, did my engine not crank and my electronics shut off? If I keep the Perko switch on # 2 setting will cranking the engine kill my deep cycles or does this still run off the starting battery? What is the best way to set up this system? Do I need to dump the Perko switch in the can and if so will I lose the ability to charge the TM battery while I am running the boat? If the batteries are fully charged will the boats altenator not put out the 14+ volts?

Thanks again,

Mark

 

[jlinder]

Re: Another battery switch/TM question

I would first look at the charging voltage. You say the voltage meter no longer says 14.5 volts. What does it say?

Dash meters are not very accurate. You really need to get a real meter and connect it to the battery while you are running. Charging should be about 13.5 to 14.5 volts.

You may have a problem with the charging circuit from the Johnson.

 

[Silvertip]

Re: Another battery switch/TM question

You seem to have a number of separate but related issues. I assume your deep cycle troller batteries wired in parallel (12V) for the trolling motor and they should definitely last longer than half a day on a 30# motor. By the way, that's a pretty small motor for an 18' boat. How you use the battery switch depends on how it's wired. The START battery is normally wired to BAT 1 and the HOUSE or TROLLING battery is wired to BAT 2. You start the engine on BAT 1, then swtich to BOTH to charge both batteries while under way. When you get to your fishing hole, switch to BAT 2. The troller and whatever other accessories you have on BAT 2 will only draw on BAT 2. BAT 1 will essentially be disconnected. When you are ready to leave, switch to BAT 1, start the engine, switch to BOTH and head to the next spot. If you switch to BAT 2 under way as you said you do, means that BAT 1 (your starting battery) is not charging. That, and the fact that the voltmeter does not read 14.5 as it once did indicates the charging system probably is not working. The voltmeter must read higher than 13 volts at anything above idle speed or it indicates a failed charging system. So you really may have four problems, improper use of the switch, a failed charging system, a potential issue with the trolling batteries or the troller itself drawing too much current, and/or a starting battery that won't hold a charge. Have all of your batteries load tested at any auto parts store. Just because you charge them does not mean they are able to hold a charge. One year old batteries can and do fail. If one is bad, when connected in parallel as yours apparently are, the bad one will draw down the good one until both are equal.

 

[flagator1]

Re: Another battery switch/TM question

Hey Guys,

Thanks for the quick reply. All great info, I will take the advice given and apply it to the current issues.

Mark

 

[drewpster]

Re: Another battery switch/TM question

Here is how the system should work. On the back of the battery switch there are three large posts. One marked (1), another marked (2), and another marked (com) or common.

Your trolling batteries should be wired in parallel. Meaning the battery posts should be connected together, positive to positive and negative to negative. Then, a cable connected at one of the positive posts on your trolling batteries should connect at the number (2) post on the back of the perko switch.

Your start battery should have a single cable connected to its positive post leading to the number (1) on the back of the perko switch.

All the battery's ground cables should be connected together and to the engine's negative cable and/ or a common negative buss bar.

Nothing else should connect to post 1 & 2 on the back of the perko switch except positive battery cables. 1 for start 2 for trolling.

The positive wire to your trolling motor should connect directly to the (com) post on the back of the perko switch. Positive wires to your engine and fuse panel should also connect at the (com) post on the back of the switch.

Nothing except power feed wires to the boat and the engine should connect at the (com) or common post on the back of the perko switch.

This means when you select position 1 on the perko switch the whole boat, including your trolling motor will run from the start battery only. (1 for start) The deep cycle batteries will be isolated (disconnected) and no power will be drawn from them.

When you select position 2 on the perko switch, the whole boat, including the trolling motor, will run from the two deep cycle batteries. The start battery will be isolated.

This also means that the engine will not charge the unselected battery when the engine is running. If you have the switch in position 1, only the start battery will be drawn from, and charged to, by the engine. If you have the switch in position 2 only the deep cycle batteries will be drawn from or charged to.

If you want to charge all the batteries with the engine while it is running, it is best to select (ALL) BEFORE starting the engine. Then when you get to the spot, shut off the engine and then select position 2. You can troll all day, run your fish finders, anchor lights, radios, electric coolers, bells, whistles and do-dads and still have a fresh battery because number 1 will be isolated. Select ALL before starting the engine. The fresh start battery will boost the engine well enough to start and while it is running it will charge your deep cycles. If the deep cycles go completely dead, select position 1. The start battery will take over and get you home.

This system works well if you are only going to use a 1-2-all switch to manage your batteries. It provides for mistakes. If you forget, and leave the switch set to one or the other battery banks, the "unselected" battery will get you started again. You must remember NOT to turn the perko switch OFF while the engine is running.

The best way to use the system is to select ALL at the dock before starting the engine. Start the engine and get to your first spot. Shut the engine down and switch to 2. Use your deep cycles all day for all functions on the boat. At days end switch to position 1. Start the engine and go to the dock. Trailer or tie up your boat and shut off the engine. Turn the switch to OFF and use your onboard charger to recharge the batteries overnight. Go the next day and repeat. This will provide you a fresh battery even if you make mistakes as long as you remember to use 2 for fishing and 1 for starting.

There are other, more automatic, battery switching/ charging systems that are more user friendly. You can set it up where everything is done automatically and you need only turn the battery switches off when the boat is not in use. However they are slightly more expensive and a bit more complicated to wire up.

This system is simple to wire and reliable to use as long as you set up good habits and use it as designed.