I disagree with Roland. I do not see a requirement for a smart regulator
depending on how the rest of the system is set up and how one actually uses the system.
For a liveaboard
the simplest setup is the standard alternator with stock dumb regulator plus solar
, a multi-step solar
regulator and some sort of energy use tracker. Let's assume there isn't enough solar to come close to keeping up with demand. First thing every morning as early as possible you want to run the engine
for 1-2hr to do all the bulk charging at as high an amperage as the batteries will take or the alternator will put out. FLAs like to charge at about 0.13C but can fast charge at up to 0.20C. For a 200a-hr bank that means 26a at 0.13C and 40a at 0.20C. The range of bulk charging is from 50% to about 75% full, or about 50a-hr for a 200a-hr bank. Actually bulk charging is anything up to 75% full but you don't want to go below 50% because loss of cycle life increases dramatically the further below 50% you regularly go. So with a stock 50a alternator starting at 50% discharge every morning you run the engine for 1h15m to 2h00m watching for the current
to start falling off on the battery monitor
then shutting the engine down and letting the solar bring the batteries up the rest of the way. Absorption charging which is the last 25% of charging takes 5-7hr (depends on condition of batteries) regardless of the charger, alternator or solar panels
and regulators you use. Increasing voltage can marginally speed up the process but damages the batteries. Once the voltage falls off, the cheap
way to proceed is letting the panels
finish the job. For a 200a-hr bank that's 50a-hr of absorption. 50a-hr means 150-200w solar capacity. A deeper implication of all this taken together is that you are using approximately 100a-hr every night. In which case you might want to spend money
to curb demand before upgrading the alternator regulator.
Alternatively you are using less per night or have significantly more solar, lets say 300w. That means you need to run the engine every several days to a week to do bulk charging to catch up from a heavy use day or a low sun day, and the panels
still provide all the absorption charging.
The case where you want the smart regulator is when the engine is the primary source of charging, you don't have significant solar, wind
or hydro or you can't find space to install enough and/or if you have a very large battery bank and a large demand. In this case you want the multi-step regulator. The cost of the solar panels
is not a good reason to upgrade your regulator. To fully charge your batteries everyday you will need to run your engine for 7-9hr. It doesn't matter if you upgrade to a smart regulator, high output alternator and AGM
batteries that can accept the high output, doing so will only shave an hour off of charging time. After bulk charging is done, the battery will only accept a decreasing amount of current
, absorption charging takes 5-7 hours regardless. If you are running the engine as the primary charging means, and you want to charge your batteries right to maximize life, you will be faced will significant fuel
bills over the medium to long term.
For $300 you can get a 4 stage Balmar
For the same $300 you can get a solar starter kit that includes a 100w rigid panel, cabling and a 30a 4 stage regulator that can handle up to 400w of input as you expand your panel inventory.