Battery banks

gofish103 · Post by **gofish103** » Sat May 09, 2009 10:22 pm

I've read all the post recently about adding batteries and chargers and inverters.

This is all new to me and here is my question.

Currently I have two batteries, factory charger and shore power.

Should I be looking to add more batteries? Should I add another bank for house batteries and separate the engine batteries. Im assuming the engine batteries are also the house batteries.

If I parallell the engine batteries and install two new house batteries will the factory charger still operate the same or do I need to get a new one that will charge all four batteries at one time????

kevin babineau · Post by **kevin babineau** » Sun May 10, 2009 2:16 pm

there r different batteries for different applications...1) the starting battery... which provides a powerful zap for starting but it doesnt hold the juice for a long time 2) the deep cycle...which doesnt have much of a zap but can hold juice for a longer time and is designed to be drained of juice and recharged over and over again 3) the dual purpose...which is the cross over u lose alittle from both sides.....in a perfect world u would have a 'bank' of starting batteries for the engine and a bank of deep cycle for the 'house'....a key to design is knowing how much power u use and how much time ur away from the ac shorepower from that u can decide on how many batteries,,how to recharge,,whether or not solar will help,,,inverters ...etc etc

wet wonder · Post by **wet wonder** » Sun May 10, 2009 3:44 pm

The way you figure out for a 12 volt system is you start by listing what you are using power for. Your present two batteries are presumably starter batteries - either you have two engines and each engine uses one battery to start, or you have one engine with a primary and backup battery.

For house battery setup, first list what your 12volt uses are. Then you go from there. So list what you'll be powering, aside from the engine system, and how much draw each has.

gofish103 · Post by **gofish103** » Sun May 10, 2009 9:18 pm

thanks guys, we dont spend much time away from the hook, but I would like for it to be an option.
would like the fridge to stay cool while underway or fishing. but really no much more

wet wonder · Post by **wet wonder** » Tue May 12, 2009 10:34 pm

If its a small norcold fridge than one 29 or 31 battery will do it for six hours or maybe more.

wet wonder · Post by **wet wonder** » Tue May 12, 2009 10:34 pm

If its a small norcold fridge than one 29 or 31 battery will do it for six hours or maybe more.

randyp · Post by **randyp** » Wed May 13, 2009 10:33 am

Just posted on the set up I have. Once you get a decent house bank in your boat you'll wonder how you ever lived without it! It's great having the capability to stay over and extended weekend without having to figure out where to plug in.

My recommendation is you have a dedicated starting battery for each engine and 2 batteries (deep cycle 120 AH or better) wired in paralled for a 240+ AH house bank). No need to charge the engine batteries as they will be charged by the alternators. Wire your AC battery charger to the house bank.

Check out the Blue Seas ACR set ups as these, in combination with a battery switch make the whole she-bang a no-brainer. I'm a big fan of their systems.

Whatever way you go, PLEASE be sure you size the wire correctly and use fuses, especially if you add an inverter or the ACR. It's only 12 volts but you're dealing with a lot of power.

LandVF36 · Post by **LandVF36** » Wed May 13, 2009 11:31 pm

There is a safety concern with wiring batteries in parrallel. When wired in parrallel, regarless of the charged state of either battery, the voltage will stay the same. If one battery starts to get weak, or worse fails, the other battery will try to "charge" the dieing one. When this happens, it can cause a fire or go boom!

To prevent this, you can install a "fuselink" or fuse block between to the to + leads. The fuse needs to be just slightly bigger than your max load or just larger than your max charging current, what ever is greater. With any luck, when one battery fails, the fuse will go long before the batteries self distruct. If you want a good plan on the right way to put this together, look at the wiring of most electric golf carts. Most are a combination of serial and parrallel wired 6V batteries with fuse links everywhere.

The manual method, and safer method, is to have a multi bank charger for the house battiers and a selector switch. You simply run the first deep cycle down and then flip to the 2nd or 3rd with a switch.

randyp · Post by **randyp** » Thu May 14, 2009 10:52 am

That's great advice about fusing between batteries. I've fused the ACR and the inverter, but have not fused between my house bank. Although they're both the same age (new last year) I'm not taking any chances.

Thanks!

ActThree · Post by **ActThree** » Thu May 14, 2009 5:03 pm

A simple solution for smaller boats that I have used for years is two relatively large (Group 27 or 30) 12-volt batteries in parallel for each engine. They can be used for starting and will act as a "house" source for many hours or overnight without problems using ordinary marine loads such as lighting or a 150-watt inverter to run a TV. If you accidentally kill the battery set, you can use the parallel switch to start that engine and re-charge with the alternator.

The size and quality of the cables is critical to get the most out of the battery system. The two batteries-per-engine setup described above on a 32-42-ft. boat requires a minimum of 1/0 gauge marine battery cable both to parallel the batteries (positive and negative) and to connect to the distribution panel, any battery switches that are used and the boat's grounding system. Manufacturers skimp here because this large gauge cable is relatively expensive and very stiff and difficult to work with. However, starting with all new batteries, 1/0 gauge cable using properly staked-on terminals with heat shrink tubing and electrical grease applied to each one - and assuming properly maintained alternators - you can cycle the batteries many hundreds of times and get five or more years of service from them.

gofish103 · Post by **gofish103** » Thu May 14, 2009 9:51 pm

Thanks guys, lots of good info that I definitely will heed! I will have someone look at it that has experience with this type of thing. all I need is the batteries to go boom!! Scarry stuff!