Why doesn't my boat charge my deep cycle batteries when I'm running it down the river?

[Bass newb]

It's got this fancy on board dual charger and I was disappointed to find out that I still have to plug it in? Is this normal? Is there a fix?   Boat is a 2016 Ranger z175.

 

Thanks.

[gulfcaptain]

Are you talking about your trolling motor batteries?  Your dual charger is there to charge your batteries when you're done fishing.  You may have an alternator on your outboard that may help keep the charge on your cranking battery, but that charger is a plug and charge when you're at home prior or after, not out on the water.

[J Francho]

Outboards provide a bit of charge to the cranking battery.  Your deep cycles should not be wired to the outboard.  This is how all bass boats are set up.

[A-Jay]

Check out this new product from Minn Kota -   I do not have or use this but seems like a good idea.

 This Alternator charger boost your trolling batteries while on the water.   It takes excess power from the outboard's alternator and delivers it to your trolling batteries to extend run times, decrease on-shore charge times and increase battery life.

A-Jay

http://www.minnkotamotors.com/Battery-Chargers/On-Board-Chargers/DC-Alternator-Chargers/

[F14A-B]

2 hours ago, J Francho said:

Outboards provide a bit of charge to the cranking battery.  Your deep cycles should not be wired to the outboard.  This is how all bass boats are set up.

Yep, "a bit of a charge" & "cranking" being the key words here. I still ran my 15 amp per hour charger at home, camp or the hotel afterwards on all three of my batts. 

[tomustang]

Your onboard charger doesn't do any good if it's not hooked up getting power while going down the lake now does it.

Most charging systems on the engine are more of a 'maintainer' than a charger and in any case only runs to the engines battery.

[Bass newb]

23 minutes ago, tomustang said:

Your onboard charger doesn't do any good if it's not hooked up getting power while going down the lake now does it.

 

Why this doesn't happen is the question. Seems like it'd be natural to wire like this but guy tells me that you don't run long enough to charge.

[Wayne P.]

Stay'N-Charge and Trollbridge are a couple more systems to charge the trolling motor battery/s from the outboard alternator.

 

[Way2slow]

Just use a very long drop cord. 

Don't know anything about your motor or size charging system, but the bulk of those systems that are supposed to charge your TM batteries off the cranking motor are basically useless.  As mentioned, once the motor has charged to cranking battery to a certain level, they will start feeding charge current to the TM batteries.  The problem with that, unless you do more running than fishing, there's never very much, if any excess.  Unless you have a very large charging system, or making long runs, the motors charging system is doing all it can do just to try and keep the cranking battery fully charged and many can't even do that.

[J Francho]

Aren't these "alternators" just rectifiers? Or am I mistaken?

[A-Jay]

5 minutes ago, J Francho said:

Aren't these "alternators" just rectifiers? Or am I mistaken?

I'm not sure I know the difference.  But the specs on the new 200XS I'm looking at says an Alternator putting out 60 amp /  756 watt.

Seems like a decent bit of juice. Clearly run duration will come into play.

https://www.mercurymarine.com/en/us/engines/outboard/optimax-and-pro-xs/pro-xs-115-250-hp/#specifications

A-Jay

[Way2slow]

That's why I said since I know nothing about what kind of motor he has.  Most of your big V-6s have gone to 60 amp alternators.  Some have even gone away from using the stator in the flywheel and installed a small belt driven alternator like you would find on small cars. It wasn't that long ago, they considered a 35 amp big enough for the big motors and even now, you can find a lot of the smaller motors still just running 16 amp charging system.  Anything you put on the smaller charging systems would be a total waste.  Those are primarily to deliver enough to run the motor without it draining on the battery when it's running, and give a small trickle charge to the cranking battery. 

Since my motor newest motor still only has a 35 amp charging system on it, I don't have experience with the 60 amp systems.  They may have enough ump to keep the battery charged and deliver some to the TM batteries with something like a Stay-in-Charge, can't speak for those.  I know I had an onboard charger in my boat for several years that had a built in system that monitored the charge level on the cranking battery and when it reached 95%, it would transfer over and start charging the TM batteries. 

I have digital charge indicators at the bow for my TM batteries and for the five years I used that charger, only a couple of times did I see an increase in the charge level on the TM batteries and those were after making long 20 and 30 mile runs.  Under normal operation where I fished for a while, cranked up to move and five minutes later cutting it back off again. The cranking battery didn't even stay fully charged.  

J Francho.  A lot of the small 16 amp systems are nothing but a rectifier.   Systems larger than that could actually over charge and damage the battery so they run a regulator built into the rectifier.  The 16 amp systems could never deliver enough charge to even a fully charged battery to over charge it, but the larger system could do that on extended runs if they didn't have the regulator.

[Bass newb]

My opti max 115 has a 60 amp alternator. 

[slonezp]

Onboard charger as the name implies is to charge the batteries without removing them from the boat. It has absolutely nothing to do with the motor charging your batteries. Pull the boat in the driveway, plug it in overnight and enjoy your next day on the water. It is best to plug the boat in after a day on the lake, charge them to full, and top off the charge overnight the day before your next trip OR once a month if the boat is being stored

[WIGuide]

@Bass newb as slo said an onboard charger is a charger that stays onboard your boat. It replaces the old system of having to charge your batteries one at a time. With your motor having the output it does you might see some benefit of using one of the other chargers mentioned for on the water charging, but you will still need to charge your batteries when you are done at the end of the day.

[Bass newb]

How do out of town bass fishermen manage all that charging crap at a hotel? Very long extension  cords?

[J Francho]

I usually get a camp site with electric hookup.  In the case of motels, I look for a place that I can park the boat right by the door and run an extension cord.

[slonezp]

57 minutes ago, Bass newb said:

How do out of town bass fishermen manage all that charging crap at a hotel? Very long extension  cords?

Any area known for fishing will normally have hotels that have electric hookups , just bring a 50ft extension cord. 

[WIGuide]

If you camp you can get a site with electric, otherwise if you're staying at a hotel, call ahead and ask. Most around fishing destinations are set up to handle that. I always bring my 100' cord though. That way if nothing else, I can park the boat outside the room and run the cord under the door inside. 

[fishnkamp]

There is one thing to consider with your question about your alternator charging your trolling motor batteries.  The alternator puts out 12 volts, which is fine when connected to one starting battery.  Most of us have 24 volt or 36 volt systems for our trolling motors.  Your  12 volt alternator would be damaged if hooked directly to a 24 or 36 volt system.  That is why several of the members have mentioned aftermarket  equipment that can do this safely.  Those units like the Minn Kota and the Stay and Charge, as well as your on board charger, have separate charging circuits for each battery. These circuits are isolated from each other, so no electrical issues occur.  When I outfit a new boat I always use short jumpers between the two trolling motor  batteries.  Then I wire my boat with two positive leads (8 gauge each) and two negative leads(also 8 gauge each) from the batteries all the way to the front and connect them to two separate thermal breakers. From the breakers I have 1 positive and 1 negative lead going to the trolling motor plug.  Since the total current travelling to the trolling motor is cut in half, 1/2 per wire, the total resistance is dropped. So this means the current drop across the circuit is also lowered  (less current wasted in heat).  As a result I never run out of juice on the lake!  I also always recharge upon returning to the motel or home. It is a simple thing to set up but it works.

[Way2slow]

WOW, somebody re-wrote the book and done got into some electrical/electronics I've never heard of. 

Paralleling two eight gauge wires from the rear to the front of the boat is going to do nothing but make ONE cable slightly smaller that if you had run one piece of 6 guage cable to start with. 

Circuit breakers should be at the battery end, not the TM end to keep from burning your boat up if they happen to short or have problems.  At the TM end, they are only going to protect it if the TM itself has a problem.  They are not resistors so they should not be limiting anything.

The only real limiting factor to the whole setup, provided it's not a large enough trolling motor you should be using larger than 6 gauge wire would be the single piece of 8 gauge wire you are running to the TM,  Then it's going to be working like resistor and over heating with the more restriction it's causing.  To the point it could actually melt.

Not sure where the voltage dividing and because it's two wires instead of one it will only draw half the current and that will let it run twice as long stuff is coming from.

The TM is a load on the battery.  The harder is pulling, the more the load it's going to place on the battery.  If the cable between the load and the battery are not large enough to handle current that load is drawing, they are going to start creating a resistance to the current and start  to heat up.  Heat is wasted energy.  At the same time, as the resistance too small of a cable increase, it's going to create a voltage drop at the load/TM so performance is going to drop.   However, the lower voltage and drop in performance is not going the increase battery run time because the heat being generated is wasting that. 

Then, what since does it make to buy a 80 pound TM to have it perform like a 60 pound TM because you are running too small of wires to it. 

If anything, you should be going to a larger 4 gauge or even a 2 gauge TM cable (which is what I run) for all battery connections and up to the TM.  This limits the amount of wasted energy from heat, lets the TM perform at it's peak and provides the most efficient operation and longest run time.

If you are running a 12 volt TM and want more run time, upgrade to a 24 volt, A 24 volt motor is about 25% more efficient than a similar size 12 volt because there is much less internal heat being (wasted energy) generated.  I don't have the numbers but I think a 36 volt adds about another 13% to that number.  The higher the voltage the more efficient.  That's why they run 600,000 volts down high tension power lines.