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battery question 1977 85 hp

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wolfpak382usa

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I've got a 1977 kingfisher with a 85 hp evinrude on it, it has 2 live wells, trolling motor, beilge pump, lights and switch for the trim. I'm getting ready to put batteries in it and was wondering if i could hook the whole boat on 24 volts or should i split it up somehow?
 
Re: battery question

Your engine only chargers at 12 Volt and has a 12 Volt system (starter, alarm, trim etc)
Why 24???
If you need 24, you have to make a separate 24 V system for those accessories.
I'm afraid you will get problems making the 85 charge a 24 Volt system. The charge amp will be about 1/2, and you have to split to 2 batteries. That itself is no problem, but normally one is kept for start and the other for accessories.
With a 24 circuit you will have to use both and risk draining the start battery.
 
Re: battery question

the only reason i was thinking of 24 volt was because it seems the motor doesn't want to start real good with one 12 volt battery, but as soon as i put 24 on it, it cranks just as soon as i turn the key. I bought a brand new stowaway 1000 cranking amp battery but it seems to be not enough. I thought about running the motor on 24 for starting and using another battery for 12 volts on every thing else.
 
Re: battery question

How do you have the batteries wired currently?

If both the positives are together and both the negatives are together that is still only a 12 volt circuit (called a parallel circuit) but has the collective "amps" of all the batteries.

A 24 volt system (series circuit) would mean that you wire the positive of one battery to the negative of the other - with the positive feed to your motor/assessories from one of the batteries and the negative from the other battery (in a 2 battery circuit) - that would give you 24 volts - and would probably fry your lights, pumps and starter on your motor...
 
Re: battery question

If your motor is not cranking properly on 12 volts

Check your battery. State of charge and a load test.

If battery Ok check all connections, including the negative/ground.

To avoid any confusion here is a diagram that explains the difference between series connection and parallel connection

scan0009.jpg
 
Re: battery question

Would you throw 24 volts to your car or truck? Of course not, and why wouldn't you? Think about it.
 
Re: battery question

i do have the batteries wired in series which gives me 24 volts but only my trolling motor is hooked to that and i have another single battery i use to run lights, beilge pump, live well, etc., but i was having a hard time getting my motor to start on the new 1000 cranking amp battery i bought without running it down so i switched my motor over to the 24 volts and it cranked everytime very quick without loosing voltage. I have taken all the connections loose and cleaned them but still the motor just turns over and over until it runs down. don't really know, but i don't want to ruin my starter if it can't handle 24 volts.
 
Re: battery question

If your new 12v starting battery will not turn your motor over fast enough to start it, you have other issues. As far as running your 24v trolling motor, you're correct to have two 12v batteries wired in series. You need three good batteries to run your system as you've described it.
 
Re: battery question

With a known good 12 volt battery, fully charged, run known good jumper cables directly to the electric starter motor. If the engine DOES NOT crank over normally, there is something wrong with the electric starter.

If on the other hand, wired directly as above, the starter DOES crank the engine over properly, you then have a loose or tight but dirty cable connection somewhere or a cable that is corroding internally. Any of these mentioned cable problems will result in a very hot cable at some point quite near the problem area.
 
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