On board charging / dual battery system / boat wiring?

[novice23]

Hi guys,

I'm looking to maximise the use of my electric motor on extended fishing trips (3-4days)

At the moment the electric motor (55lb minn kota) runs off a 120amphr deepcycle battery and i carry a second 90amp hr battery for backup. Carrying 2 batteries gets me through 3 days but if there is an alternative so i can ditch the second battery or get more days/use out of the batteries i've got i would jump at it.

The minn kota draws max of 50amps.

The outboard produces 17amps for charging and this charges the cranking battery not the electric motor batteries. The cranking battery runs the following:
· Sounder & NMEA network between motor and sounder- draws 0.05amps and on all the time
· Bilge Pump -draws 3amps but rarely used
· Bait tank pump – 3amps potentially run for 1 minute every ½ hr if live baiting
· Nav Lights 20mA x 3 run for 10-12hrs overnight
· Deck lighting inside - 0.8amps run for rerigging / cookups – 2hrs per day.

Is there a better way of running this show?

[shane450]

There are plenty of different ways to achieve what your after all of them have pro s and cons .

You can install a smart solenoid , charges your start battery until its full then links your bow mount battery to the outboard motor charge , how successful this will be depends on how long you run to your destinations . i also don t 100%trust the smart solenoids , having had two fail on me over the years in my 4x4 .

What I do is take my Honda generator and CTEK and charge my battery at the end of each day for an hour or so

[novice23]

Thanks Shane,
I completely overlooked the generator as an option.
Any other ideas out there?

[lucee81]

Hi Novice23

Not sure if this is of any help but i Run a Redarc VSR (voltage sensitive relay) between the 2 batteries and have never had a problem, you can wire this up to charge which ever battery you choose first, i have put a simple toggle switch on mine, so if my cranking battery goes flat i just flick the switch and start of my aux battery, once the motor is started the first battery gets charged until full then the aux batt gets charged.

Lucas

[shane450]

Hi Novice23

Not sure if this is of any help but i Run a Redarc VSR (voltage sensitive relay) between the 2 batteries and have never had a problem, you can wire this up to charge which ever battery you choose first, i have put a simple toggle switch on mine, so if my cranking battery goes flat i just flick the switch and start of my aux battery, once the motor is started the first battery gets charged until full then the aux batt gets charged.

Lucas

I ve had a redarc fail on me in my 4x4 ( they tell me the new design is better so I gave it another chance in my new truck , it made the cape and back a few weeks ago so fingers crossed )

[lucee81]

I ve had a redarc fail on me in my 4x4 ( they tell me the new design is better so I gave it another chance in my new truck , it made the cape and back a few weeks ago so fingers crossed )

I only installed mine this year so im assuming its the new design. I purchase a lot of 12/24v electrical goods and have not come across problems with redarc (yet) May just have to speak with my rep and see what the story is there...

[shane450]

I ve had a redarc fail on me in my 4x4 ( they tell me the new design is better so I gave it another chance in my new truck , it made the cape and back a few weeks ago so fingers crossed )

I only installed mine this year so im assuming its the new design. I purchase a lot of 12/24v electrical goods and have not come across problems with redarc (yet) May just have to speak with my rep and see what the story is there...

A few of my friends have had redarcs fail as well, having said that several of my crew including myself have had various battery systems fail at different times over the years including the very expensive ones, always a pain in the ass when you have a fridge full of food . The redarc is probably the simplest of the smart solenoids and like I said I ve given them another go in my new troopy , the new design has the clear moulding around the voltage sensor .

I think for the intended purpose in the original post ,a system for his boat ( and i kind of assumed he would be going off the beaten track ) I d advise keep things as simple as possible , generator and charger , thats what I do and it works perfect , added bonus when your away remote its handy to have if your car battery depletes you have the genny to charge that too .

[novice23]

Cheers guys.

[marty666]

what about solar if it is practical

[driveon]

At the moment the electric motor (55lb minn kota) runs off a 120amphr deepcycle battery and i carry a second 90amp hr battery for backup.

Hi novice23, with that small an alternator output, unless you are taking hours to get to where you are going to be trolling, you won’t get much charge out of a 17 amp output.

You say you use one battery and have the other battery as a backup.

You would actually get more usable capacity if you connected the two batteries in parallel and run your motor of both batteries.

The reason for this is that the higher the current draw applied to a lead acid battery, the less energy you will get.

This example is an exaggeration but it roughly works out at say your 120 might give you 5 hours of use and your 90 might give you 3.5 hour, but if your wire them together in parallel, your might get 10 to 12 hours use, or even more.

By wiring the two batteries together, you are literally halving the current load on each battery and while this won’t double their output energy, it will give you quite a considerable increase in energy available.

BTW, if you do connect them in parallel to run your motor, leave them that way while you charge them.

[novice23]

Thanks for all the replies guys.
Very helpful and some options i didn't consider.
I will link the batteries up to get a bit more distance out of them and will go with a generator on the extended trips for now. Later down the track i might wire up an anderson plug on the back of the 4x4 with a redarc system - that way i will have alot more output to charge the batteries while driving between fishing destinations.
Cheers!