Wiring 12v battery bank for best efficiency

Hello all, I'm somewhat of a novice to all this so please forgive me if I'm asking obvious questions.
We have a bank of 4 x 130Ahr leisure batteries aboard our narrowboat, charged by a 495w solar system and the 70A engine alternator.
The batteries are wired in parallel at present (I've attached a very basic wiring diagram of our current setup).
I've been doing some reading on wiring batteries for longer life/best efficiency, which has turned into a bit of a minefield. There seems to be conflicting ideas on how best to do it. I wondered if I could get some advice please.
I've been doing some reading on wiring batteries for longer life/best efficiency, which has turned into a bit of a minefield. There seems to be conflicting ideas on how best to do it. I wondered if I could get some advice please.
The only thing I should mention is our battery bank is spilt, with two on the LHS on the boat and two on the RHS. This makes having all cables the same length pretty difficult
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Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
http://smartgauge.co.uk/batt_con.html
And the use of fuses/breakers to reduce the chances of short circuits/fires. Each + wire (assuming negative grounded DC power system) should have a fuse/breaker rated to protect that wire from over current (short circuits). The fuse/breaker is typically mounted as close to the battery bank as practicable. Lead acid batteries, and particularly a bunch connected in parallel can output 100's to 1,000 Amperes into a dead short. Breakers are nice because you can also use them as an On/Off Switch too (breakers and fuses need to be rated for DC use).
For charging via solar--Two calculations are suggested... One based on the size of the battery bank, the second based on your actual power usage and hours of sun per day (Guessing you are in the UK--Being Narrow Boat is a term for boats that are using the large canal network in the UK, and I checked your IP address/location as a moderator).
Solar Panels... 1-2% rate of charge for purely "floating/storage of a charged battery bank" (off season). 5% minimum suggested rated of charge for a daily cycling battery bank... 10%-13% to as high as 20% for full time off grid system (more panels, less genset usage). The math would be:
- 4 * 130 AH= 520AH @ 12 volts (house bank)
- 520 AH * 14.5 volts charging * 1/0.77 panel+controller derarings * 0.02 rate of charge = 196 Watt float/storage
- 520 AH * 14.5 volts charging * 1/0.77 panel+controller derarings * 0.05 rate of charge = 490 Watt minimum
- 520 AH * 14.5 volts charging * 1/0.77 panel+controller derarings * 0.10 rate of charge = 979 Watt nominal
- 520 AH * 14.5 volts charging * 1/0.77 panel+controller derarings * 0.13 rate of charge = 1,273 Watt typical "cost effective" maximum
Of course, you have limited roof/deck space for panels. And you may want to run at least a float panel for solar charging panel of the starter battery if you do not have shore power for over winter.To estimate sizing your solar array based on energy usage... You can get the hours of sun per day based on your location you cruise mostly, and also look at tilting vs flat mounted panels and how it affects your solar harvest. For example, Leeds UK, facing south, flat vs 36 degrees from vertical (or 54 degrees from horizontal):
http://www.solarelectricityhandbook.com/solar-irradiance.html
Leeds
Measured in kWh/m2/day onto a horizontal surface:Average Solar Insolation figures
Leeds
Measured in kWh/m2/day onto a solar panel set at a 36° angle from vertical:Average Solar Insolation figures
(For best year-round performance)
- 12 volts * 130 AH * 0.85 AC inverter eff = 1,326 Watt*Hours per day
And lets say that your "break even" solar is 3 hours of sun per day (that is 3 hours of "noon time" equivalent sun):- 1,326 WH per day * 1/0.52 off grid AC Solar system eff * 1/3.0 hours of sun (April-September) = 850 Watt Array minimum
I think you may have shore power through the RCD breaker (240 VAC to AC battery charger, and AC inverter auto transfer switch?). Do you have RCD (GFI) on your AC outlets to shut down AC power when the inverter is running (or shore power)?I guess most of your travels are in fresh water (not salt)--But things can be pretty complicated when dealing with electricity and boats. Shore power/grounding/zinc blocks/avoiding currents that can corrode the propeller and bearings...
Not sure exactly how far you want to go down this rabbit hole of safety... Here is a quick summary of some of the issues:
https://www.westmarine.com/WestAdvisor/Ten-Deadly-Conditions
Anyway, welcome to the forum WeeVee, and let us know how you would like the conversation to proceed.
-Bill