On board battery charging

[ROWINGADUBAY]

I read somewhere that a simple wire from your starting battery to your trolling motor battery will charge your trolling motor battery while your engine is running if this is true can I make a plug that plugs into where my trolling motor plugs into from the battery to where my front navigation light plugs in [the navigation lights run off the starting batery], then in theory I can charge my trolling motor battery while my engine is running by turning on my navigation lights

The reason I would do it this way is because these two plugs are about 12" apart and the wires could be put away easily I could also control the charging by flicking the switch on the nav lights wich has protection from a circuit breaker and in an emergency if my starting battery were to fail I could back charge it from the trolling motor battery by doing the same thing.

So my questions are would it work?

has anyone came up with a similiar setup for charging batteries

Edited July 14, 2009 by paintsniffer
added info

[Jig Man]

I don't know of an engine that has an alternator that is sufficient to keep tmotor batteries charged unless you want to do a whole bunch of running and almost no fishing.

However, there is a little gizmo that will boost your ability to charge your batteries while you motor or while you are towing the boat. Check this out StayNCharge by Retrotec

[Kajan]

Look at this one Charging Batteries as you use them

[ROWINGADUBAY]

I like them both very much. I read up all I could on both of the suggested battery chargers and I couldnt find any info on how they actually work do they make the increase alternator voltage or amperage or do they just re-route the electricity that comes from your alternator? If they just reroute the output I may have found a better way!! Less cash too!!!

I checked the specs on my 2000 90 h.p mercury and the alternator has a useable output of 20 amps max the dealer mechanic said it would hit this at about 2000-2500 RPM and it should put out about 10 amps at idle the newer motors put out even more up to 40 amps and ten amps should be plenty to keep up a charge a trolling motor battery

I read up on this quite a bit and made some phone calls I am pretty sure a system like the stay in charge could be done for less than half the price of the one they sell using two of these "phase switches"

Bass Pro Shops XPS 12V Phase Charger Northern Industrial Battery Isolator 90 Amp, Model# BI-90A1B2 | Energy Storage Batteries | Northern Tool + Equipment

you would use one in between your car battery and your boat cranking battery and one between your boats cranking batterry I believe either one would work in either spot but I am just not sure of northerns switch being waterproof

so when your car battery is charged it sends juice to the crank battery then when that one is charged it will send juice to the troll batteries when your boat is on the water it would do the same charge the crank then the troll all for around 100 bucks.you could also throw in a multi meter from harbour frieght for five bucks and have a digital display.

I have never tried this setup but in theory it should work but I know there is a big difference in the real world and if anyone knows if this setup would not work or have problems please chime in I know someone out there has to know more than me about this stuff. I will wait a little while to purchase one of these switches to use between the crank and the troll batt to see if any one has a better or cost effective way if you do think it would work I would like to hear from you too .I will post back when I get it all setup and give the voltage and amp readings from both my truck and the outboard

Thank you all

George

[hazmail]

As you say George, it's all white man magic, I know nothing about this mysterious 'alchemy' either, but it sounds good to me, so keep us posted, until an Electrical Engineer chimes in and shoots your idea down in flames - anyway it will be fun while it lasts, and again, it sound really good to me, can't wait to try it .pete

[Vodkaman]

I am not the electrical engineer that you are looking for, but I have read your article and the web link several times and this is how I see it:

The phase charger relay is energised/switched when the two wire connection to the alternator lights up, indicating that the car battery is charged. The connection between the car battery and the boat motor battery is then made (a bit like jump leads between batteries).

This then starts to drain your car battery until the charged wire of the alternator switches off and de-energises the relay, thus breaking the connection. So the relay will switch on and off, until both batteries are charged.

Placing an additional phase switch between the main boat battery and the trolling motor battery will work and switch the connection on and off relative to the car batteries state of charge, NOT the main boat battery, it is all about the connection to the alternator, which is monitoring the car battery.

BUT, after reading this link: http://www.carbatteryshop.co.uk/carbatteryinformation.php

then maybe the whole idea is not such a good one, as I suspect that unless the motors were of a similar size as the car battery, then they would be subject to overcharging, which would result in overheating, evapouration of electrolyte and buckling of the lead plates.

Like I said, I am not an electrical engineer and you should seek expert advice before trying these ideas.

Dave

Edited July 27, 2009 by Vodkaman

[ROWINGADUBAY]

the setup would be car + to switch then wire from switch to boat crank positive the next would be the same but from boat start+ to switch then a wire to the troll batt +

that way the charge in series car batt then boat crank batt then trolling bat I believe the swicth checks alternator output by voltage via the battery lines not a seperate wire to the switch

Dave

thanks alot for your advice I am worried about rapid discharge and charge the other systems seem to work and I see some rapid chargers that put out up to 20 amps without any bad reports there is no rush on setting this up I just think it would help extend trolling time and keep me from being stranded with dead batteries

Thanks George

[nova]

Here's something I've been thinking about and this seems to be the perfect time to ask.

What about using one of those small 5 or 10 amp solar panels to supply a charge while you're out on the water?

www.novalures.com

[ROWINGADUBAY]

I pretty much gave up on this idea after my dad said "for the price of those phase switches you could just buy one or two more batteries and double or triple the run time of your electric motor you dumb@%^" and he is right the set-up would be nice for a pro or someone that takes a vacation hopping from one lake to another but I do niether

so now I can use my 12v trolling motor all day with three batteries hooked up in paralell

As far as solar panels go I guess they are great for battery maintenance "float and trickle charging" but not made for bringing a half dead battery up to full charge if it is extended run time you want get another battery.

[BobP]

One waring about using a parallel connection between the starting and trolling motor batteries - if you run a sonar unit, don't do it! Sonars and GPS units are usually powered by the starting battery. In the case of sonar, you don't want any connection with the trolling motor because the electric motor in the TM will cause serious interference on your sonar.