Quote:
Originally Posted by rocks
The battery bank is 540 amps @ 24 volts. We charge to 28.2 volts. On most days the volts drops to about 25.3 volts.
The alternators are 300 amps each. Only charge at total max 250 amps from alternators, they are setup to start charging at about 1100 rpm .The Battery bank always is loaded with air con, navgear ,kitchen, laptops, fridgers and freezers etc. As the battery reaches 28.2 volt the alternators are putting out very little amps.
The starting batteries only are used for starting no other loads.
At max of 28.2 volts I am 2.6 volts under the max volts and the low volts are control by the inverter and solar regulator so no need for BMS. My max load is about 4000 watts, the batteries can handle over 10x that load no need for a BMS.
I do have balances for each string but only need to use them when charging over 28.4 volts that’s why only charging to 28.2 volts
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Thank you for these details.
Your 300A alternators are heavy duty ones, they can run 60-80% of that a long time. With 250A charge one has to do 125A of 300A capacity ,which is 40%...piece of cake for this ones.
An average mono sailing boat alternator is somewhere between 50 and 100A and not heavy duty, if they can do 40% which is 20 - 40A constant on 1500-1800 RPM then you are lucky...
Connecting this one without an regulator will fry it soon. Well the alt should be just backup, much better is main solar and backup use a portable gasoline genny like thw
honda 20i and charge via the
shore power charger. Much more efficient.
Don't forget that a 120A
Balmar heavy duty with external regulator will easyly eat - 7 till 10hp (compared to a 70A standard) from your
engine which is mostly just enough
power and raise diesel
consumption significantly. I keep my standard 60A and use the victron smart charger which limits it between 20 and 30A and switches to the starter lead if LTOs are full to protect it. Just not to waste this energy when i need to motor anyhow. This need 2-3hp and no raise in diesel
consumption. Main source is solar, then wind gen, then portable zipper 2000W genny (semipermanent installed connected to a 25l
outboard fuel tank which gives it around 50-60h running without refueling) and only then alternator via
engine. Well i only need to run the genny an hour when its 3 days totally cloudy and no wind. Never the engine till now.
A tip: when your batteries are 95% full and you have enough solar time left, I run the
water boiler
heater via a timer that switches it automatically off after 90min, then my 40l tank is to max hot from 20 degrees
water. Like this i use this energy, always have full batteries and on most days a full hot water tank in the evening or next morning.