"It would also cause some problems... For example when you go to start your engine, it would automatically be connected to the house bank. If your house bank was already lower in voltage than the engine battery it would draw current from the engine start battery, possibly allot of current. That would make the engine battery allot less effective at its primary job, which is starting the engine."
Sorry wrong,
This is not correct as the solenoid is connected to the ACC terminal of a key switch , so during start the solenoid is not powered , the batts do not see each other..
So there is no draw down of the start system , except the starter itself..
The beauty of the system is the lack of downside , it does the job with no operator knowledge/understanding/input required.
Being reliable and cheap is just a bonus.
The house batts will drag down the start batt voltage when they are combined which is what gets the house charged., but NOT the start batt set.
A very modest sized alt will usually hold the charge to at least 12.6 -8 , the point where the start is fully charged and the house being lower takes most of the voltage as charge.
It takes at least 1 volt of higher than resting voltage to charge the house set in modest time , but the start is not being run down if the supplied voltage is its normal float voltage .
As the house gets charged the puny alt will slowly be able to raise the voltage to hopefully 14 or so where both systems are fully charged.
This is much faster with a 3 stage V reg than with an imbecile auto one wire alt.V regulator.
With a nice big truck 150A alt and a 3 stage regulator the start batt will probably never go as low as float during a huge almost dead house bank charge.
120V Battery chargers can seldom make their rated amperage at a good voltage with less than a 10KW noisemaker , so a 150A alt belted to the noisemaker is a better investment if you anchor out a lot..
OK FF I missed that you have to replace your key switches with automotive types that have an ACC position.
IF you connect the relay up as you described.
IF you replace your key switches then the system will act as if you had a manual on-off switch combining the banks whenever you have your engine running.
The challenge remains that the system you're describing
ONLY works when you are running your engine.
It
DOES NOT work when you are plugged into shore power, or recharging via the generator
UNLESS you have a multi bank battery charger.
So, in the end, by using the relay VS the ACR you have a system that
WILL NOT WORK with any of the very high quality inverter/chargers that are on the market.
You have saved a few bucks by buying the relay over the ACR but you have spent much of that savings on new key switches. You have also had to run new wire all the way to your dash and increased the complexity of your wiring to boot.
and BTW... your comment
120V Battery chargers can seldom make their rated amperage at a good voltage with less than a 10KW noisemaker , so a 150A alt belted to the noisemaker is a better investment if you anchor out a lot..
is pure fiction. 100% fiction
As an example... On my last boat I was able to make full rated capacity of my 50 amp battery charger using my little $750 honda 1,000 watt portable generator. On my current boat I have a 9 kw Northern lights generator and it will produce 75 amps of pure sine wave power.
Heres the facts about generators and the quality of power they produce...
A rotating brushless generator by its very nature produces a pure sinusodial wave form. The only problem we have is in the voltage regulation section.
The concept is that a generator uses DC current to drive its output. If that DC current is "clean" the output will be a pure sine wave.
The voltage regulators job is to convert some of the AC output of the generator to a DC current that is inversly proportional to the output voltage of the generator. Less generator output = more DC current. Thats how it keeps the voltage stady under varying load conditions.
The problem with voltage regulators is that they use varying technologies to produce that DC current. Cheap home generators (not the inverter type) use capacitors to produce the DC current. The DC current is not perfectly clean, thats why you can see your lights flicker when using a capacitor regulated generator.
The other methods of voltage regulation are transformer and solid state. A transformer regulator like I've seen on some generators does a pretty good job. They react very quickly to varying loads but are not as "clean" as the solid state types. A transformer regulator is still a very good regulator and few battery chargers will have any issues with power produced from one.
A solid state regulator on the other hand is almost perfect. The power out is a clean DC current, therefore the power out of the generator is a pure sine wave.
