[727hog]

I want to charge my 2 24V trolling motor batteries with with my 12V Outboard(150 Johnson) alernator while running.. My idea was to put a keyed cut off (interuptor type) switch between the trolling motor batteries(jumper line) and this would turn those 2 batteries into a 12V System. I Thought I could also put the same type cuttoff switch on the Positive wire from my alternator to the two trolling batteries. So when I get ready to run , I just pull the key from the jumper wire and put it in the positive wire. I don't know if I would need one on the neg wire to the alternator.
This is my untrained, half-witted idea. I would appreciate some advice and guidance on wiring this. I researched the threads and want to thank Silvertip in advance.

[tashasdaddy]

1st you need a battery switch, also you have to be very careful how it is wired, as it is extremely easy to blow the electronics with in the motor. i'm not versed enough to help. just a warning not to go experimenting. could be very expensive.

[JCF350]

Best thing would be to use 6 or 7 pin trailer connectors. Battery side would hook up one wire per post. Trolling Motor plug would jumpered in series for 24V. Charging harness set up for parallel connection.

No chance of cross connections or forgetting one step of the process (or getting them mixed up. And no chance of running your trolling while charging.

[Silvertip]

I take it you have a two wire system between the batteries and the trolling motor connector -- correct? There are a couple of ways to do this but in my view, the cleanest way would be to use a four-wire system between the batteries and then swap the two pin plug receptacle for a four wire setup (even though the motor only requires two. These systems typically included a "Run/Charge" switch that essentially paralleled the two batteries for charging through the receptacle. I have a diagram of that system but I'll need to look at it for modifications to charge from the engine. Check back later today.

[727hog]

I just got a new trolling motor and plan put to put in all new connectors and wiring. So, 2 or 4 wire system makes no difference. The 4 wire idea is great. If I understand I could just unplug the trolling motor from the recepticle and plug in the alternator 4 wire plug. I don't unerstand where/how th"e Run/Charge switch" functions and gets my batteries from series to parrallel.

[Silvertip]

Here is a simple system that is used on some boats that allows charging through the trolling motor plug. Each battery has two wires routed to the front of the boat and in this case a three prong receptacle is used because some trollers allow running on 12V AND 24V. Although you could use this system, You would need to run a third pair of wires from the START battery to a three prong plug. You would then unplug the troller and plug in the CHARGE connector. HOWEVER -- there is no protection in that system meaning you could inadvertently have the switch set to RUN (24V for trolling) when you plugged in the CHARGE plug. You don't want to know what would happen. So the second diagram, although a bit more complicated, offers full protection and one switch operation with no plugging/unplugging.


In this diagram, the switch controls a relay that does all the switching for you and essentially isolates the engine charging system from the 24V system when the switch is OFF. It even isolates the ground line so there is no chance of any electrical feedback to the charging system. The relay could be replaced with an industrial 3PST rotary or toggle switch. You could even use three individual SPST relays if you wish and trigger all three simultaneously but that leaves a little more opportunity for failure of one relay to transfer causing some issues. The theory for the switching is explained on the diagram. If you want to discuss this some more, just PM me. Perhaps someone else has done this and will add their comments so don't dash off until you've thought this through fully. You can research relays and switches on-line by inserting 3PST Switches or 3PST relays or Industrial Switches and Relays in the Google/Yahoo search box.

[JCF350]

I may be blind but I do not see a 12V neg connection for battery #2 in diagram #2 for parallel mode. not mentioned in the description where it gets neg 12V. mentions disconnecting batt#2 neg from Batt #1 pos but no connection to batt#2 Neg for 12V

[Silvertip]

Good eye! I'll fix that.

[727hog]

Thanks again Silver, Diagram 2 is exactly what I was looking for.

[Silvertip]

OK -- but don't use it because there is an error that I'm fixing. I won't get to the corrected version until tomorrow sometime. The new diagram will retain a 3PST relay but is wired differently. Hang in there -- but you could start looking for a switch or relay (high current needed) which ever you prefer to use. Just remember that all of this wiring must carry "potentially" the full output of the alternator which is close to 35A at wide open throttle. That means you should use 10 gauge wire so the switch/relay should preferably have screw terminals but spade connections are ok.

[PondTunes]

Originally Posted by 727hog

I want to charge my 2 24V trolling motor batteries with with my 12V Outboard(150 Johnson) alernator while running..

When you hook the (2) 12 volt (Deep cycle?) batteries up in parallel it makes them look like one great big battery... Your outboard engine alternator doesn't have near the output of a marine inboard style alternator. To fully recharge the pair of deep cycles it is going to take some real long trips at WOT to even dent them. If you are burning through 2 batteries in an outing it might be more practical to invest in a multi bank onboard charger and another set of batteries.

Use one set until dead then switch to the second bank, when you get home charge them all using the onboard charger.

[Silvertip]

That motor has a 35A alternator. While it's true you won't charge the batteries fully in a 10 minute run back to the dock or between fishing holes, it will extend the time on the water.

[727hog]

Guys, I use my boat on a lake and never use all the juice in the batteries. I have a dock at my house that has no electricity. I like to leave my boat in the water for a few weeks at a time. All I have to charge them with at the dock is a solar panel that that won't charge them back if I used them hard. And then I have to pull the boat out. If I charge them With some juice from my outboard, that would prevent me from the hassle of trailering the boat.During my search for the switch, I ran across this http://www.yandina.com Check out the Trollbridge 24

[Silvertip]

Here's the revised diagram. JCF, if you are still lurking, since four eyes are better than two (usually) you might take a gander at this diagram to see if I overlooked something. Don't think I did, but I thought that last time.