just wet back to my boat that is on shore charge. Sure enough the ACRs are closed. I think someone mentioned that the factory now puts in single bank chargers due to the fact that ACRs are in. In this case, due the specs of the ACRs we really have just one bank of 4 batteries in parallel as the ACRs combine if they see on any input 13.6v for more than 30 secs, 13.0v for more than 90 seconds. And they open at 12.35V when below for more than 10 secs, or 12.75V for more than 30 secs. If you have solar panels, you most likely have have more than 12.75 on house, which keeps the connection to the engine and thruster batteries connected all times. During night, on the hook and no generator or engine running, the batteries are most likely separated which serves the purpose of not discharging the starter battery with house loads. During the day, if your consumption is high enough even with solar on, eventually battery voltage may go below the ACR open voltage protecting your engine and thruster batteries as intended.
With all the batteries in parallel for most of the time there is a problem if the battery types are not the same. In my case I have 2 house batts and one thruster battery DC27MF 890MCA deep cycle battery and one 27SM-8MF 1000CCA starter battery.
Haven't evaluated what this does when they are parallel most of the times.
Ideally, you want a smart charger for each bank that is fed either by shore power/generator or engine alternator. So technically we just need a 110/12v powersupply feeding into the 3 bank charger where the powersupply output is replaced with the alternator output when the engine is running. Would need some lockout mode to in case shore power and engine are running.
Alternatively, pro mariner make a "ProIsoCharger" that takes alternator input and feeds between 1-3 banks of batteries with a smart charger therefore eliminating the ACRs. Those IsoChargers come in different capacities and need to match the alternator output. This charger seems to charge batteries in sequence not in parallel, starting with bank 1 first, then bank 2 and so forth before it puts a maintenance charge on all banks. It also seems to perform a function where it provides power to other banks if there is a high demand thusly eliminating the need of a parallel switch that we have in our boats. Haven't seen a spec how much current they can bridge. They do caution that the unit must not be allowed to have starter current go thru it which means it is useless for that function or providing power to the thrusters.
They also have a single bank version which will use the alternator output and apply multistage charging which could be used with ACRs. However, due to the different SOC of banks of batteries, different charge regimens should be applied to extend the life of batteries.
The best way to inhibit the operation of the ACRs is to apply +12v to the SI+ input which can be derived from the LED that indicates that the charger is on.
The desired logic is to have batteries properly charging when power is available, isolated when not charging and paralleled only when needed at certain demands which I assume to be manually induced only. Solution is a three bank charger from shore power, 3 bank charger from alternator, ACRs replaced with parallel switch (perhaps remotely controlled) for short term emergency connection (or ACRs inhibited to be used if you have solar).
I think this summarizes this subject and I will shut up unless someone has some compelling arguments that justify an answer 🙂
