Battery lighting and inverter circuits

[Boat builder]

I want to build a boat with a 12v battery circuit powering lights and inverters in all the compartments. (9 in total). I plan to have a bank of batteries totalling 4000ah, this will be charged via solar panels and a charging panel fed from a generator which I don't want running all the time (ideally for a few hours in the afternoon just to top up the batteries).

Each compartment will have 6 lights and 2x 500w inverters and 2 fans.
Has anyone got any formulas I should use to work out power usage and charge rates etc.

All advice is welcome.

 

[audioguru]

Compact fluorescent light bulbs are available with a 12V input rating. They have 4 times the efficiency of incandescent light bulbs.
Then an inverter is not needed.

 

[Boat builder]

The inverters will be for sockets to run things like laptop computers.

 

[ronv]

Thats a bit like running a house off of batteries. You don't say the wattage of the lights and fans but if we use the 1000 watts for the inverters we can get an idea. If we have to put 1200 watts into the inverter to get 1000 out (80% effecient) that is 100 amps for each compartment or 900 amps total. This puts the run time at say 2 to 3 hours since you don't want the batteries to go completely dead.

 

[nsaspook]

I want to build a boat with a 12v battery circuit powering lights and inverters in all the compartments. (9 in total). I plan to have a bank of batteries totalling 4000ah, this will be charged via solar panels and a charging panel fed from a generator which I don't want running all the time (ideally for a few hours in the afternoon just to top up the batteries).

Each compartment will have 6 lights and 2x 500w inverters and 2 fans.
Has anyone got any formulas I should use to work out power usage and charge rates etc.

All advice is welcome.

The first thing is to NOT use a 12vdc battery buss for that kind of power level. Redesign the system using a 48VDC battery buss, solar charge controller, generator charger and main central inverter for all high power loads with a smaller inverter for lighting. I would stick with 120AC as the standard instead of using 12vdc and power small DC loads with a DC/DC converter from 48vdc to 12vdc or a separate much smaller 12vdc aux battery system charged from the main buss.

This is a typical application:
https://www.electro-tech-online.com/custompdfs/2012/09/PNADO640.pdf

 

[bryan1]

Hi Boat Builder,
Now you say you will have 4000AH of batteries, what type are ? fully sealed wet cell etc.......

My recommendation would be to go for a 24 volt array and just use one inverter that is capable of sustaining ALL the loads on at once and forget those modified sinewave inverters.

Also how watts of PV will you be installing as a 4000AH array will need around 2Kw of PV to supply the required charge without the need to run a genset for long periods. Now for a charger to run off the genset have a look around for a forklift traction charger as those babies are the best solid state devices on the market and can be easily adapted for off grid use if required.

I have lived off the grid now for over 9 years and have helped friends out on power systems for boats too and I'm happy to give you advise if you want it.

Regards Bryan

 

[RCinFLA]

4000 ah's of 12v lead acid batteries is about 2000 lbs. of batteries. Hope it doesn't sink the boat.