batteries

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boatcomfort

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I have three 27 size batteries in parallel to use with an inverter. From these 3 batteries in parallel I need to get 24VDC for a trolling motor. What's the best way to go. I appreciate all suggestions
 
Can you fit a four? two in parallel and two in series. Three would create in imbalance and I'm not sure this is a good idea.
 
You have a boat big enough for 3 house batteries and also can use a "trolley" (is trolling?) motor?

George
 
This is a marine surveying boat. All these house batteries are for the Electronics.
 
We are not getting a lot of info but to get 24v you will need to use the current bank as one Battery and add another in series the capacity will be equal to one battery for the trolley, whatever that is.
 
quote:
Originally posted by boatcomfort

I have three 27 size batteries in parallel to use with an inverter. From these 3 batteries in parallel I need to get 24VDC for a trolling motor. What's the best way to go. I appreciate all suggestions

Click to expand...


Two 12V batteries in series will give you 24V.

Four 12V batteries in parallel/series will give you 24V.

Four 6V batteries (edit: in series) will give you 24V.

A trolling motor would probably be better served by a DEEP CYCLE 6V series/parallel set-up using golf cart batteries. You may well be able to fit 4 6V batteries in roughly the same physical space you're using now. (Compare Trojan T-105s for specs, then shop various equivalents fro price.)

Your 12V batteries are more likely at best "dual purpose" -- not actually designed for deep cycling as are golf cart batteries.

-Chris
 
your batteries cant be hooked up in series and parallel at the same time.Series is needed for the 24V.

You could disconnect the electronics, reconfigure the batteries and run the motor but I suspect that is not what you want.

Battery powered propulsion requires a loot of capacity for any distance or size boat.
 
Connect two batteries in series (connect one pos to one neg). This will get you 24 volts

Then connect each battery in parallel to power your 12v electronics

The only issue will be charging. The third battery (the one not hooked to the trolling motor) will probably be overcharged
 
Get a 120 volt AC to 24 volt DC power supply and run it off of the inverter.
 
"Connect two batteries in series (connect one pos to one neg). This will get you 24 volts

Then connect each battery in parallel to power your 12v electronics"

Now you have a cable that creates dead short across the first battery.
 
quote:
Originally posted by caltexfla

"Connect two batteries in series (connect one pos to one neg). This will get you 24 volts

Then connect each battery in parallel to power your 12v electronics"

Now you have a cable that creates dead short across the first battery.

Click to expand...

This is what I was thinking but I would like to see both sides of the 12 volt load balanced hence the need for 4 batteries. This said it would still work with three or even two batteries.
 
[qoute]This said it would still work with three or even two batteries.[/quote]
What is "it"?

The way I see it, is take two 12's and create his 24v bank. Have the remaining 12 completely unwired from the others and it, or additional batteries in parallel, run the 12v stuff.
The mix approach is very dangerous.
 
If you have two of the batteries in series you will have 24 volt two batteries in parallel still gives you 12 volt with double the amps. If you create two banks of batteries two in each bank in parallel then join the two bank in series you will have a hefty 12 and 24 volt setup. Of course you could also just have two batteries in series for your 24 volt and one or two others for your 12 volt systems but you will need a 24 volt charger to maintain this system. It is not uncommon in the security system industry to have a similar setup being most fire equipment is 24 volt and most security equipment is 12 volt. Years ago we did the same for the 6 and 12 volt systems. I have no need for 24 volts on my boat but I do have three 8Ds on my boat one single 8D for my starboard motor and two 8Ds in parallel for my port/house bank ever since I change to this setup I run my generator a lot less.
 
Thanks everybody for the info. I need to maintain the 3 batteries in parallel for the 12 volts on the electronics. I have to use the electronics when I'm trolling and the trolling motor is 24VDC. I need to have 24VDC and 12 VDC at the same time. I only can had one more battery. The 12VDC supplies one inverter for the computer systems and some electronics taken from the 12VDC. A generator can't be used because of noise.
 
Tony I have a few concerns what are you using to charge these batteries and what is the current configuration?
Does this boat have engine(s) as well? If so we need to consider the charging output.
Do you have a shore power hookup or is this a boat on a trailer that you bring home and charge with a wall plug?
These are all factors which could great change what you would or could safely do!
 
How many amps of current do you need for your trolling motor? DC-to-DC boost converters are now very efficient (over 90%) and can supply lots of current. With one of these you would just leave your batteries connected as they are now, supply 12 VDC to the boost converter and output your desired 24 VDC. Just do a Google search on "DC/DC boost converter" to see what is available.

Mike
 
It is simple just add a new battery with the plus side going to the trolling motor and the neg going to the positive of all the other batts . Hook the neg of the trolling motor to the neg of all the original batts. Now you have center tap 24 v with the center tap at 12v as before.

The capacity at 12v will be the capacity of the new 12v battery but at 24v
 
quote:
Originally posted by pdecat

It is simple just add a new battery with the plus side going to the trolling motor and the neg going to all the other negs. Now you have center tap 24 v with the center tap at 12v as before.

The capacity at 12v will be the capacity of the new 12v battery but at 24v

Click to expand...


HUH??!!

There is some not very good, and in at least one case, very dangerous advice being given on this thread.

If you can add another battery, the create a 24 v bank and a 12 volt bank, May need to get rid of one existing battery and get two higher amp hour replacements to run the inverter.
 
Good catch, I fixed it. Much ado about a simple thing.
 
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