Connecting a battery in series???

[Tinpusher1]

I recently purchased a 1995 neptune 180 cc. This boat came from the factory as a one battery boat, what I mean by that is all electric devices ( including tilt and trim bilge etc) are connected to a single battery. When I installed a 55lbs thrust trolling motor I thought it would be a good idea to connect all the electronics on the new deep cycle trolling battery leaving the cranking battery to the motor only. The boat has two sets of cables going to the cranking battery, one for the starter, and the other smaller set of wires to power everything else. The genius that I am (lol) thought this would be easy. Take the smaller leads, add an extension and connect them to the deep cycle battery. Well, to my surprise, when I connected the smaller set of leads to the new deep cycle battery the tilt and trim stopped working. It appears that a circuit is not complete when connecting the leads this way. Once installed back on the cranking battery with the starter leads the tilt and trim work again. How can I fix my boat so that tilt and trim,bilge, bait tank, etc work from the deep cycle trolling battery and the cranking happens from a cranking battery? Also, if I cannot do this, will I fry something by connecting a second battery to the first. Will this make the boat a 24volt system or a big 12volt system. Connecting the batteries in series does not sound right to me! Thanks in advance.

 

[Georgesalmon]

Re: Connecting a battery in series???

you can connect the batteries in parallel, + to + and neg to neg. Best bet and very common would be to get a battery switch, Off, batt 1, batt2, and both. Even then its typical to have all the engine stuff connected to the "cranking" battery, and the other loads to the house battery. The trim n tilt is normally on the engine battery even if you install a switch.

 

[Bondo]

Re: Connecting a battery in series???

I recently purchased a 1995 neptune 180 cc. This boat came from the factory as a one battery boat, what I mean by that is all electric devices ( including tilt and trim bilge etc) are connected to a single battery. When I installed a 55lbs thrust trolling motor I thought it would be a good idea to connect all the electronics on the new deep cycle trolling battery leaving the cranking battery to the motor only. The boat has two sets of cables going to the cranking battery, one for the starter, and the other smaller set of wires to power everything else. The genius that I am (lol) thought this would be easy. Take the smaller leads, add an extension and connect them to the deep cycle battery. Well, to my surprise, when I connected the smaller set of leads to the new deep cycle battery the tilt and trim stopped working. It appears that a circuit is not complete when connecting the leads this way. Once installed back on the cranking battery with the starter leads the tilt and trim work again. How can I fix my boat so that tilt and trim,bilge, bait tank, etc work from the deep cycle trolling battery and the cranking happens from a cranking battery? Also, if I cannot do this, will I fry something by connecting a second battery to the first. Will this make the boat a 24volt system or a big 12volt system. Connecting the batteries in series does not sound right to me! Thanks in advance.

Ayuh,.... Did ya also move the Ground for those accessories to the other battery,..??

Any "Circuit" has to be a full circle,...

 

[Splat]

Re: Connecting a battery in series???

You need to run a jumper between the two grounds on the batteries. You can then move your accessory wire over to the other battery. This will however do nothing to charge that battery.

For that you will need to install a ACR or switch between the two battery positives.

 

[Tinpusher1]

Re: Connecting a battery in series???

Great stuff, thanks to all!

 

[Tinpusher1]

Re: Connecting a battery in series???

Do I need a jumper if the cranking battery has the house - lead attached to it? Basically, a three wing nut set up, starter leads attached to cranking battery, house + lead attached to new deep cycle battery and - house lead attached to the cranking battery?

 

[Grub54891]

Re: Connecting a battery in series???

Throw out the wingnuts,use regular ss nuts,or ss nylocks.

 

[Silvertip]

Re: Connecting a battery in series???

And just for clarification:

1) Two batteries in SERIES produces 24 volts which would fry all of your 12 volt accessories. (The title of your post said "In Series")
2) Two batteries in PARALLEL still produces 12 volts but doubles the current capacity of the batteries provided they are the same size/type
3) You did neither of these if all you do is transfer the accessory load to the second battery.
4) The second battery will not be charged by the engine.
5) As stated, you need a dual battery switch or ACR to fully implement a dual battery system.

 

[Tinpusher1]

Re: Connecting a battery in series???

Great information, thank you! Got to love the knowledge base on iboats!!! I will be purchasing a dual battery switch.