Carver 3207 - adding a bank of batteries - questions

That's a lot of questions to answer at once. Do you now have just one battery for the house loads? What size and capacity is it? That information really is needed to help decide the best way to approach your requirements.

Do you really need a separate battery bank for the stereo? What are your normal house loads while overnighting away from shore power?

How much physical space do you have available to install more batteries without running very long cables?

Consider that those little inverters normally output a square wave and many "wall wart" or laptop power supplies don't like that waveform. If you have a sine waver inverter it may be a better idea just to plug the laptop into a utility outlet after increasing house bank capacity.

It is very important to avoid overcomplication.

What are you running off the inverter/charger now? Is that a sine wave unit?

A lot depends on your time solely on battery power in between charging. If only one night out at a time, then what you've described above seems to be overkill. If you go out for 3 days at a time, then probably ok.

First legal piece of advice: DO NOT SITUATE YOUR INVERTER IN THE ENGINE ROOM IF IT IS NOT MARINE RATED. If something goes poof on you, that will be an insurance sticky point.

I can tell you what my set up is on my 325AC '96, if that helps.

2 dual purpose group 24 house batteries on a switch which are for starting, refrig, all 12 volt lights and stereo head with 1 power amp for a sub.

2 (6) volt Duralast [autozone] batteries in series solely powering a 2000 watt inverter behind the stbd side a/c panel. I got these in a pinch although they're really like lawn equipment batt's, so better ones needed like deep cycle golf cart batts.

1 starting battery for the generator.

The only batteries that run low at the end of many hours are the inverter batt's because of the kids using the 26" flat panel to watch movies or play PS3, and using their laptops.

I'm not sure that you need the extra batt's to run your stereo amps. We originally had 3 alpines running off the 2 house batt's without a problem, but I removed 2 of the amps in lieu of using the Sony head's power for the 4 full range speakers, and powering a sub using 1 alpine amp.

Before adding batteries and charging capacity you must determine your electrical usage. Your primary user is probably your refrig. Remember your battery capacity must be twice your usage so as not to deplete your batteries below 50%. Lastly, figure a battery charger will replace about 75% of it's rated capacity before it goes to a float charge. That's a rough number but you should get the idea. If not the point that I'm making is the charge capacity must be greater than the usage. Don't think that a 100 amp charger will replace 100 amps in an hour. Or an alternator for that matter.

I have 3 battery banks on my 35 Carver.

#1: One 95 AH gen start battery
#2: One 105 AH engine start battery
#3: 4 105 AH House batteries.

The gen and engine start batteries don't need to have much capacity as they are hardly used, generally once a day when cruising.

My house banks has 420 AH but only 210 is usable because you don't want to deplete more than half the battery capacity.
I estimate my electrical usage at 300 amps per day when on the hook, primarily due to an older norcold refrig. So I recharge twice a day once in the morning and once in the evening. My 30 amp 3 bank charger is useless when on the hook (I would have to run the genset 10 hrs per day to replace those 300 amps) so I must recharge using the engine alternators which are 100 amp each. Running the engines at 1000 rpm for an hour twice a day pretty much does it. But if I'm on the hook for several days I would need to run the engines twice that.

A battery schematic is attached.