Inverter/charger installation on dual engine

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Inverter/charger installation on dual engine

Postby Aquaholic » Sat Jun 17, 2017 11:02 am

We have a brand new Magnum 2012 inverter/charger and are wanting to install ourselves.....if possible. I'm researching we are seeing two scenarios.
One is to combine all the batteries in parallel into one bank to increase useable amp hours and so it will charge all batteries when connected to shore power. do you, or can you, attached both alternators to the single battery bank?
Second scenario is to leave as two banks (one per engine as it is set up now w house bank on starboard side) and then connecting inverter/charger to the starboard side. This scenario leaves no charger connected to the port side.
Does anyone have input or suggestions on how to best hook this up on a dual engine scenario? A diagram would be great!.....if anyone has one :-). Thanks
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Re: Inverter/charger installation on dual engine

Postby BlueSkye » Sat Jun 17, 2017 9:13 pm

Hi Aquaholic,

Two alternators on one battery bank doesn't sound like a good idea to me. Your voltage regulators would be fighting each other. In case of alternator failure while cruising I have jumpered the starting batteries, but just with one alternator running and connected. I have a 40 amp charger on my house bank, but I do not charge the starting batteries with it. They have their own charger, two channels.

To do what you say you need two "battery isolators". One bank gets charged first then the charge can spill over to the other bank through the isolator. There is a problem charging the house bank and the starting batteries this way. Your house bank has to be the one connected to the inverter so your starting batteries won't get a charge until the house bank is topped off.

If you charge one of the starting batteries first and let the house bank charge second through the battery isolator then when you are cruising the engine alternator will be under tremendous load trying to keep the house bank charged. The standard alternator will not live long under such loads. I put a high amp alternator on one engine to charge up the house bank this way while cruising, but that is a whole other project.

Just a thought, get advice on correct wire gauge for the amps and distance, and put fuses in the wires to each and every bank.

Last edited by BlueSkye on Sun Jun 18, 2017 9:46 am, edited 1 time in total.
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Re: Inverter/charger installation on dual engine

Postby bill » Sat Jun 17, 2017 9:50 pm

My thoughts :|
Keep original set up, that is one battery for port engine and one battery for starboard.

Use only one of these starting batteries for the house 12 volt equipment. 8-)

God idea to install a parallel switch to jump the two batteries together, just in case one battery loses its charge. :roll:

Install a bank of 6 volt gulf cart batteries dedicated to the Magnum 2012 invert er/charger.You will need to know what the load is on the 120 volt equipment you want to run while underway or at anchor.:geek:

You may have to purchase a 100 amp alternator for one of the engines. Us a battery isolater switch that will charge the starting battery that also feeds the 12 volt house circuits. This switch will also charge the bank of 6 volt batteries when underway. Every thing will have to be fused accordingly. ;)

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Re: Inverter/charger installation on dual engine

Postby Fastjeff » Sun Jun 18, 2017 6:02 am

I've learned from painful ($$$) experience that each battery needs its own, dedicated charger.

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Re: Inverter/charger installation on dual engine

Postby barkleydave » Sun Jun 18, 2017 8:48 am

My setup is similar to Bill's. My Xantrex 1800 is fed from my STB battery bank only! I have a Parallel switch which will strap both banks for starting if needed. ( I use it when I start the Port so as not to drain the STB bank on startup when going out to anchor etc.)

My house batteries consist of 2 six volt golf cart batteries. (Just replaced the bank after 8 years!) My Port bank is one GR 24 starting battery and I do have a spare not connected just in case. I used to have the Port batteries in parallel but had to disconnect when I install a new "Smart" battery charger. Yea right! Why you ask.... The new chargers go through varies maint. cycles and the problem with two in parallel is the cycle will stop when the first one hits max threshold so as they say... "hind tit" looses. I could do the six volt duals on the Port as well but not a big fan of using deep cycles for starting batteries.

I looked into AGM but for my charger to work all the batteries in both banks must be AGM... OUCH ! Remember DO NOT INSTALL the inverter in the engine compartment. They usually are NOT ignition protected unless it USCG approval for enclosed spaces.

Remember as stated earlier proper cable size and fuses are very important. Wire size is based on maximum wattage of your inverter and the total round trip length of the cable. (Total of Positive and Negative cable length) Here is a link that might help guide you and there are many others.

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Re: Inverter/charger installation on dual engine

Postby Aquaholic » Tue Jun 20, 2017 7:00 pm

Thanks all.....I think we have our plan and proper materials to get r dun now. We are going to utilize 4 6v batteries as our bank. Your responses were helpful!
1989 32 Marinette Sedan
McConnelsville OH
Muskingum River