12 or 24 volts needed

I have a 18' 1986 ranger 350. the guy that sold me the boat said that the trolling motor and aireator and the bilge pump and the lights ran off of the 2 trolling batteries but after looking and digging around I find that everything runs off of the starting battery except the trolling motor. the 2 batteries are wired for 24 volts and my trolling motor will run off either voltage 12 or 24. last time my wife and friends went camping for 3 days we got stranded out on the lake because of a dead starting battery. would it not be better to just wire the 2 trolling batteries in series to 12 volts so I can run everything to the 2 trolling batteries so it would save my cranking battery. whats the deal with 24 volts when most everything is only 12 volts. thanks guys

24V is used only for a 24V trolling motor. Nothing else uses it unless you have something off the wall installed.

Running the TM on 24V cuts the amount of current required in half, which means you can use smaller wires and everything is more efficient. You don't want bilge pumps and lights running off a battery you intentionally run down when you use it. You probably have a bad starting battery, or it isn't being charged when you aren't on the water. Get a short set of jumper cables to carry in the boat so you can jump from one of the TM batteries if the cranking battery goes dead.

If your motor has one, big outboards pull start pretty easily if they have already been cranked that day.. Just in case.

have you thought about splitting up the two trolling batteries, using a 12v for the trolling motor, and a 12v for the lights, bilge, aireator, accessories etc. that way you could run your trolling battery completely down, and not have to worry about needing a bilge and not having one. i run high powered spots on my extra battery also, and don't want these to run down the cranking battery.

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Originally Posted by katbird

I have a 18' 1986 ranger 350. the guy that sold me the boat said that the trolling motor and aireator and the bilge pump and the lights ran off of the 2 trolling batteries but after looking and digging around I find that everything runs off of the starting battery except the trolling motor. the 2 batteries are wired for 24 volts and my trolling motor will run off either voltage 12 or 24. last time my wife and friends went camping for 3 days we got stranded out on the lake because of a dead starting battery. would it not be better to just wire the 2 trolling batteries in series to 12 volts so I can run everything to the 2 trolling batteries so it would save my cranking battery. whats the deal with 24 volts when most everything is only 12 volts. thanks guys

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You definitely don't want anything designed to run on 12V, hooked up to batteries wired for 24V !! You will fry those electronics/accessories !!
If you wish to keep the 24V capability for your trolling motor ... and given the size/weight of your boat, you should ... then the other accessories should be running off the starter battery.
ALL THREE batteries need to be recharged, daily, after being used. If you were "camping" ... did you have access to elec. hookup, to recharge the batteries ?? Were you using the lights, or bilge, or aerator quite a bit ? Sounds like the battery wasn't at full charge, to start with ... or else it wasn't recharged, after extended use. Big motors, that are cold natured and require a bit of cranking to start, pull a lot of charge from the starter battery. But, they should have an alternator, to put back some of that charge ... while running. They won't usually recharge the battery completely, though, so you will still have to put that battery on a charging system to get it fully charged up.
Yes, you can wire the trolling motor batteries in series, to have a longer lasting 12V output ... and wire the accessories to run off them. The only ones I wouldn't do that with, are the depth finders. Trolling motor & depth finders running off the same battery, will create elec. interference in the depth finders.
Starter batteries are not usually deep cycle ... they're designed to have a certain amount of charge removed (when starting motor), then have the motor's alternator put some of that charge back. If it's being used for accessories, as well as the big motor, and those accessories are used extensively, it can fail on you ... when the battery's charge drops below a certain point, and it can no longer put out enough juice to crank the big motor. Jumper cables will work ... but, you'd have to unhook the 24V setup, and use the jumper cables on a single 12V Deep Cycle TM battery. You don't want to blow fuses, melt connections, or fry your big motor's electronics, by hooking it up to a 24V setup.
Of course, you can always carry a jumper battery, for piece of mind. I carry one in my truck, and it goes in the boat when I'm fishing. It's only another 20-30lbs of weight, tucks neatly under the console, and serves many purposes (I run spotlight, & blacklights off of it ... and it can also be used to recharge a cell phone).
They generally look something like this "Grip" brand jumper :

http://cdn.overstock.com/images/products/P952920.jpg

and cost from $60 and up (though, I bought both of mine on sale, and paid around $35 each)
The picture is for reference only, and not a product endorsement ... my jumpers are a "Prestone" & a "Vector".

.... luck2ya ... cp :cool:

Yes, you can wire the trolling motor batteries in series, to have a longer lasting 12V output ...

No No No. 2 batteries in series will give you 24VDC. (neg to pos)
2 batteries in parallel will double your amperage at 12VDC. (neg to neg and pos to pos). CP hasn't had his coffee yet this morning. LOL

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Originally Posted by IBNFSHN

Yes, you can wire the trolling motor batteries in series, to have a longer lasting 12V output ...

No No No. 2 batteries in series will give you 24VDC. (neg to pos)
2 batteries in parallel will double your amperage at 12VDC. (neg to neg and pos to pos). CP hasn't had his coffee yet this morning. LOL

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I meant parallel .. not series --- my bad. (my previous boat, and my partners boat, both run off of ONE single battery ... don't have much experience with multiple battery setups. Think I was quoting Katbird, when I said "series" ... should have done a bit more research ;) )

I don't drink coffee :eek: ... but, I hadn't started on my morning can of Diet Pepsi :p ... so I must have been a little off my game ;) (good of an excuse as any .... LOL!!)

... cp :cool:

thanks guys
Ithink that I will just leave it at 24 volts for trolling and 12 volts starting. I noticed my trolling motor which is an old johnson stays on 12 volts but it will run on either. I have a 2 bank onboard charger for my trolling batteries that stay pluged up but like you say the starting battery may be going bad or the altenator is bad. I found a bad fuse and replaced it but it shoots everytime I replace it so now I have the dash panel off and I hate to work on something that someone else has rigged. there are wires hanging and cut wires and connection blocks on every wire. I'm going to just trace down every wire and get rid of whats not needed. I noticed the areator auto timing switch was eat up with rust so i'll remove it and bypass it. I have a 120 johnson 4 cyl. on the boat and I noticed the tach was set at 6 and it has 2,3,4,6 on the settings. seems like mercury is set on what stator you are running like if you have a 12 pole stator then set it to 6 on the tach but I don't know about johnson. I know I have some strange readings on my tach. I bought a 1999 mercury optimax 200 hp to put on my ranger and it is still in the shipping crate. I did'nt know that it was going to be a monster and I was afraid to put it on my boat. I hope to sell it if I can it only has 215 hours and looks brand new. well since its getting cold weather I should have plenty time to get mine rewired and thanks for the info. I fish at rhodhiss and lake hickory and if we don't see a lot of rain soon they say rhodhiss has just 3 more months of drinking water. heck I won't need a boat just a net for dipping. :D

Your Johnson has a 12 pole stator just like the Mercs. Check your charging circuit as that can affect your tach as well as keeping your starting battery charged. The simplest way to do it is to check the voltage at the battery with the motor off. Then start it and recheck again. As you approach 2K RPM you should see an increase in voltage. If you have ever hooked up the starting battery backwards, even for a split second, your regulator/rectifier is toast. That short you have could fry it also.

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Originally Posted by IBNFSHN

Yes, you can wire the trolling motor batteries in series, to have a longer lasting 12V output ...

No No No. 2 batteries in series will give you 24VDC. (neg to pos)
2 batteries in parallel will double your amperage at 12VDC. (neg to neg and pos to pos). CP hasn't had his coffee yet this morning. LOL

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I'm glad you cleared that up, yes two batteries in series produces 24v from positive to negative, you can also hook up a series/parallel circuit, if you want to run 24v trolling motor wire the batteries in series, you can add a parallel 12v circuit by just tapping off one batterys positive and negative for your interior lights, spots, etc. its done all the time, and perfectly safe if you install fusses in each circuit.

Even with the trolling motor batteries connected in series for 24 volt, you can use one for an occasional 12v source (like a light) simply by using the + and - terminals of the SAME battery. I asked the same question on this board a couple of months ago. When I nightstalk, I don't use the trolling motor much, so I hook the light to one TM battery (leaving the two batteries connected) Works like a charm. No need for an extra battery just to run the light. Should work the same way if you had to jump start the big motor.
Just be sure you DON'T hook to the + of one battery and the - of the other or you will fry things not made for 24V.

I still carry three batteries... one for starting and accessories but I don't want to chance running it down by using it to power fishing lights too.

What do you mean got that cleared up? I am more confused than ever. Would someone please do it one more time, how do you hook up two 12v batteries to double the capacity for a 12v trolling motor? I'm not interested in 12/24 or 24, just 12v, but have two batteries to extend the time of use.

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Originally Posted by toothpick

What do you mean got that cleared up? I am more confused than ever. Would someone please do it one more time, how do you hook up two 12v batteries to double the capacity for a 12v trolling motor? I'm not interested in 12/24 or 24, just 12v, but have two batteries to extend the time of use.

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Hook the batteries positive to positve and negative to negative.