All good points -- I wish I had disconnected the starter battery from the Amp-L-Start to see if the house lights went out. I cannot see what else could have powered them, since the Unity was parked in my garage (no solar or alternator) and not plugged in. Besides, Joel admitted "both battery banks are connected together". A diode in the path would block reverse current but there'd be some voltage drop too. If that's OK maybe one could be added in series with the Amp-L-Start.You would think there would be a diode in the circuit to prevent any reverse flow... plus if you have lithium batteries, they should be at a higher voltage than the starter battery preventing any reverse flow. In the case where you disconnected your house batteries, I would only expect power going into the house side wiring through the charging device when the vehicle is running (thus allowing you lights to come on), OR if there is still any solar contribution, the house side wiring would get some power unless you removed the solar fuse.
As a test, with your house batteries disconnected, you could lift one of the AMP-L-START leads and see if your RV house lights go out. That would almost certainly provide the confirmation that power can go in reverse through the AMP-L-START device... or not
The dc-dc charger is only producing amps when the engine/alternator is running. In that event the alternator is charging the starter battery and most likely topping it off with plenty of excess to keep the 30 amp dc-dc charger sending to the house battery. Do I have that wrong, or will I be in a loop until the starter battery charges?But keep in mind that the Amp-L-Start is another load on all the charging devices, and could in theory consume a big part of the Victron DC/DC converter's output. If the starter battery voltage is high enough that wouldn't happen. I'm guessing it could be more of a problem with smart alternators where their voltage can be all over the place.
Sounds right. Another way to look at it is the DC to DC charger is drawing off the starter battery as long as the starter battery remains above 13.3 and the vehicle running sense line (blue wire) is hot at your converter. Since the alternator is connected to the starter battery, and the input to the DC to DC converter is connected to the starter battery, the voltages are all the same. The alternator is always reading that voltage at the starter battery positive post to regulate the current. As the DC to DC converter draws the starter battery to lower voltage, the alternator increases its output voltage to push more current into the system. As long as the vehicle is running and the alternator is turning (and the alternator internal regulator is working), the starter battery is healthy (above 13.3 volts), the system should be working properly. Note that the Sterling does its own regulation which is dictated by the battery chemistry profile and house battery state-of-charge, so it will not accept more current than needed.The dc-dc charger is only producing amps when the engine/alternator is running. In that event the alternator is charging the starter battery and most likely topping it off with plenty of excess to keep the 30 amp dc-dc charger sending to the house battery. Do I have that wrong?
Most of the voltage-sensing charging devices (such as the BlueSea ACRs) state (somewhere, perhaps in tiny print) whether they're one-way or bi-directional. (BlueSea sells both flavors).You would think there would be a diode in the circuit to prevent any reverse flow...
That would almost certainly provide the confirmation that power can go in reverse through the AMP-L-START device... or not
Unfortunately, that won't work if you simply use the MB's EK1 "ignition on" (or D+) terminal.I received this reply from Amp-L-Start. It's an interesting solution.
In applications where charging sources other than the alternator are supplying power to the house batteries while the motorhome is under way, the simplest solution is to connect AMP-L-START's GND. [-] terminal to the motorhome's Ignition [+] wire.
Basically, whenever the ignition switch is on, it supplies the GND. [-] terminal with roughly the same voltage as is present on the HOUSE [+] and STARTING [+] terminals, effectively shutting off power to the AMP-L-START.
With no power being supplied to the AMP-L-START, it doesn't pass current in either direction - and is effectively bypassed. Naturally, while in this state, it draws no current.
When the ignition switch is off (i.e., your motorhome is parked), it drops down to zero volts, allowing the AMP-L-START to operate normally.
The black box is really just control electronics for the solenoid coil. It incorporates a wait time (I'm guessing a minute or two) and it requires the charging voltage (measured at the starter battery) to be above a certain voltage for so long (I think 13.5 or 13.8). when the conditions are met, it applies voltage to the solenoid coil so that it closes in and connects the 2 batteries together. If, for some reason, the starter battery drops below a threshold voltage (possibly 13.2), the control box (called IRD) opens the voltage to the solenoid coil, opening the contacts and allowing the starter battery to continue to charge at what ever the (regulated) alternator can deliver. Exact voltages and delay times for those operations can be found in the manual and the manual can easily be found by searching for Itellitec model 000-00629-120.That's not an MB-installed isolation relay, so bets are even further off...
I believe what you have listed as "isolator relay" (with the three thin wires) is really a time-delay relay.
Instead of using the Sprinter's D+ (alternator running) signal, they simply watch the "ignition on", but hold off on actuating the "isolator solenoid" for some number of minutes (5? 15?).
Thank you. That will save me much frustration, as will this entire thread which I just re-read. Note to self, do that more often.When I tried to disable the Amp-L-Start by disconnecting only the starter battery, it would beep sometimes and not stop until I connected the battery again. It seemed random and I couldn't figure out why, but I knew if I disconnected both batteries from the Amp-L-Start that it couldn't beep, so that's how I disable it now.