Single battery or need a dual setup?

[LattimerII]

If I were to try and run this amp

http://www.jlaudio.com/m700-5-marine-audio-m-series-amplifiers-98274

Could I get by with a large cranking/deep cycle, or is a dual battery setup a must with this load? I might run it for up to a few hours at a time without engine running, but probably rarely and not at full volume. The stereo would most often be the only electrical equipment running while anchored.

 

[Todd4]

Re: Single battery or need a dual setup?

It's really a personal preference, but I've recently contemplated this very issue. Can you get by? Yes. Do you want to get by? Got jumper cables and a good tow rope? Years ago, I've stranded myself more than once (dead battery by playing the radio too long) and had to pull start an 85 hp Force. It can be done. So I'm adding a dedicated house battery. I can literally kill that deep cycle (not that I'd want to) and still have a fully charged cranking battery to get home. I plan on spending the night on the boat (anchor light must be on all night) so the piece of mind is worth it to me. You've got some pretty serious power there - If you have the room - I'd go for a dedicated house battery. If not, just keep a close eye on your battery voltage. As an alternative some boaters will carry a fully charged spare - just in case - and swap the batteries out if they run the start battery down too low.

Some other things to consider: You have to manage your batteries on board (switch for isolating the batteries for use and charging). You have to recharge (and keep charged) every battery in your boat. An onboard AC battery charger (with a trickle charge feature) is a very convenient accessory - one plug and your done.

I'm currently in the process of adding a house battery, relocating and isolating my start battery, and wiring up a 24 V trolling motor (that's 4 batteries). I'll have both AC and DC chargers onboard (that's a lot of wire), so my answer is probably a little biased.

Todd

 

[Bondo]

Re: Single battery or need a dual setup?

If I were to try and run this amp

http://www.jlaudio.com/m700-5-marine-audio-m-series-amplifiers-98274

Could I get by with a large cranking/deep cycle, or is a dual battery setup a must with this load? I might run it for up to a few hours at a time without engine running, but probably rarely and not at full volume. The stereo would most often be the only electrical equipment running while anchored.

Ayuh,.... With a single battery,.... IF ya play it too long,.... yer paddlin' home....

2 batteries, 'n a Switch, you can always start the motor....

 

[Jlawsen]

Re: Single battery or need a dual setup?

Ayuh,.... With a single battery,.... IF ya play it too long,.... yer paddlin' home....

2 batteries, 'n a Switch, you can always start the motor....

Exactly...

 

[LattimerII]

Re: Single battery or need a dual setup?

Pretty much what I thought the answer might be. Thanks guys. Now I just have to consider my options with adding a second battery. (automated vs switch)

 

[Bondo]

Re: Single battery or need a dual setup?

Pretty much what I thought the answer might be. Thanks guys. Now I just have to consider my options with adding a second battery. (automated vs switch)

Ayuh,....

 

[Jlawsen]

Re: Single battery or need a dual setup?

Pretty much what I thought the answer might be. Thanks guys. Now I just have to consider my options with adding a second battery. (automated vs switch)

Grab one of the Blue Sea Add a Battery setups. It'll run you about 140.00 and worth every last penny. There are much better solutions but they're overly complex and expensive for what you want to do. The Blue Sea unit will work just fine.

 

[Todd4]

Re: Single battery or need a dual setup?

If you use a manual switch, when you switch it to "both" you just connected your good starting battery to your really low house battery. They will tend to average each other out (start battery discharges into your house battery) while you're running motor is trying to slowly charge both back up. If your house battery is really low, might be better to start your engine off of your start battery and then after a few minutes switch over to your house battery only. That would charge your house battery (SLOWLY) and not discharge your start battery. In any event your motor's alternator really isn't designed to recharge any battery (just maintain) so you would have to run your motor a long time to actually recharge a low battery.

If you go automated, then your start battery will be charged first (to ~14 Volts) before the charger will switch over to charge your house battery. An automated charger should have isolation circuitry to prevent one battery from discharging into another. At least thats the way my Minn Kota DC charger works.

Then when you get home (or to the dock) you still have to recharge your house battery and maintain your start battery while waiting to go out the next time. If you have access to AC power, you can do that with a couple of Battery Tenders. All this is just things you have to consider when deciding what system you want to design.

Hope this helped.

Todd

 

[MH Hawker]

Re: Single battery or need a dual setup?

I consider a battery like a bucket that holds amps. Depending on how many amps you use determine how big of a bucket you need.

In my case I night fish using a fish finder, live well, running lights and depending on conditions a set of HID fog lights and a 1.5 million CP aircraft landing light as a search light and of course a 400 watt stereo system.

My charging system on the boat is on the smallish side a 6 amp, so I installed a percent of charge meter to keep a eye on it. I use a group 31 battery, my thought was to use the biggest bucket I could and monitor how much I used. I didn't want to use 2 battery's just to keep the weight down, and so far its worked out fine. A normal nights fishing runs it down to 80 %.

My boat is kept on a wet slip and the slips don't have shore power, but I have the option of having the marina staff pull and charge my battery. So far that hasn't been necessary. I often take my wife and DIL and grandkids out and that has been more than enough to keep it charged batteries state of charge normally some where between 70 to 100 % and while it may not be the best for a long battery life it works fine, I haven't had it pull start the motor or have the marina charge it.

I consider a battery a consumable, just like fuel. If I get the warranty life out of it great if not then I will stick in a new one.

 

[NHGuy]

Re: Single battery or need a dual setup?

And if you are lazy or don't get to the 2nd battery installation in time you can bring along a jump pack.