View Full Version : Second Battery in parallel

05-16-2014, 06:57 PM
Does anyone have batteries connected in parallel on a closed bow prostar 190? I have to add a second battery for my amplifier but don't have room for it in the stern behind the bench seat. I think my only option is to put it in the bow. Can I run the connection wires for the batteries that far?

05-16-2014, 08:06 PM
I don't see any problems with having the batteries in different locations as long as you use properly sized cables for the length of run that is needed.

05-16-2014, 08:35 PM
Why do you have to add a battery in parallel to the main cranking for the amp?

05-16-2014, 08:53 PM

05-17-2014, 01:44 AM
I wasn't positive I needed the second battery but from what I have read it's not a good idea to have the amp powered by my 1 cranking battery.

05-17-2014, 08:16 AM
If you wire that 2nd battery to the original battery in parallel, they become one larger battery. So at the end of the day, your amp would still be running off your one cranking battery.

I am a HUGE fan of having 2 batteries in a boat, but not wired together, but rather as separate banks isolated by a manual switch, etc.

The only thing "wrong", if one wants to use that term, with having a stereo draw off the one cranking battery, is it limits your play time while at anchor. Other then that, there is nothing electrically wrong with it. A dual battery setup simply allows us to keep a battery in reserve, and play the tunes while the engine is off.

Sorry for the added info, I realize its not actually answering your original question.

05-17-2014, 03:32 PM

05-17-2014, 04:06 PM
^ I see the obvious Perko, but what is the brand/make/model of the battery isolator on the bottom there? I think I need one right? currently I have two batteries (1 cranking, 1 deep cycle) and 1 perko.

05-17-2014, 06:19 PM

Jeff d
05-17-2014, 06:31 PM
People run a single or even two amps with one battery all the time. Unless you're the type to sit with the engine off and play the radio for hours then you don't necessarily need a second battery. A regular cranking battery isn't ideal but will be ok as long as you don't "deep cycle" it too often. A "dual purpose" marine battery is an ok compromise for single battery setups. The dual purpose battery will be more tolerant of deep cycles than a normal cranking battery and offer more cranking amps than a comparable deep cycle battery.

I have had a 900 watt rms amp in my boat for 3 seasons now and have never once drained my dual purpose group 31 battery even after playing the radio with the engine off for a couple of hours.

If you want to play it safe just get one of these jump packs:

You'll need a bigger one like that for a V8 so don't go get the $50 ones. The nice thing about them is that they can be used for your tow vehicle or to assist other boaters. The bad thing is that you have to remember to move it back into the boat if you take it out.

05-17-2014, 08:07 PM
I keep a second battery as a precaution ( not connected to anything ). I was thinking of adding the Perko to keep from wrenching .... Still don't have it.

Btw I run two amps on a single batt but I typically do not to play music for long unless underway.