turbopilot
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My 2016 Unity MB electrical system is currently equipped with two LifeLine AGM house batteries (220ah), 5 GoPower 100 watt flex panels (up to 500 watts output), 100 ah AGM cab battery and Intellitec Isolator Relay.
The Intellitec Isolator Relay (IIR) is a "low cost" approach to managing multiple batteries. So while the device is cheap "i.e. low cost" it seriously restricts your ability to intelligently manage the batteries and electrical system in the Unity.
The IIR connects the house electric system to the cab electrical system. The device lives under the passenger seat. It's operation is very simple, it looks for the voltage on the cab side to rise above 13.1 volts for 12 seconds, then it closes the connection between the house and cab electrical system. The device does not care what the voltage is on the house side and it provides no options to connect the two sides unless the voltage on the ignition circuit is higher than 13.3v for 12 seconds.
Given the capability of my Unity electric system (particularly the addition of up to 30 amps of solar power) I made the decision to upgrade the IIR and replace it with a Blue Sea ML-ACR Automatic Charging Relay. The ML-ACR is available on Amazon for $202.94.
The Blue Sea ML-ACR offers many advantages over the simple IIR. The ML-ACR has three modes: OFF, Automatic Combine and Manual Combine. In the OFF mode the relay disconnects the cab and camper electrical system. In the Manual Combine mode the ML-ACR connects the two electrical system with a manual switch controlled by the operator.
The magic in this device is the Automatic Combine mode. In this mode the device will automatically connect the two electrical systems any time it senses voltage on either side (cab or camper) to be above 13.5V for 30 seconds or 13.0V for 90 seconds. Likewise the ML-ACR in the Automatic Combine mode will disconnect the cab and camper electrical systems anytime the voltage on either side is below 9.6V(under voltage lockout), below 12.35V for 10 seconds, below 12.75V for 30 seconds or above 16. 2V(over voltage lockout).
In the Automatic Combine mode the ML-ACR is basically looking at voltages on both the camper and cab side of the electrical system and combines the electrical systems any time the voltages are compatible with one or the other electrical systems being charged (i.e. charger, solar or cab alternator).
Here are some images of the exchange of the IIR for the ML-ACR.
This is the passenger seat pedestal. Note the installation of the awing LED and awing in/out switch was not very "fancy".
Here is a closer look at how the switches were installed:
Here is a look at the IIR as installed by LTV in the passenger seat pedestal. The solenoid and IIR controller are mounted on the board. Note cables are just held down with aluminum tape
:
Here is how it looks after the Blue Sea ML-ACR is installed and the installation cleaned up:
And finally I took the opportunity to "upgrade" the switch panel on the side of the seat pedestal to include the ML-ACR control switch and provisions to monitor cab voltage when the ignition is on:
I had a Blue Sea ML-ACR in my last RV so I thought I would share some circumstances where this device provides all sorts of extra options for battery management in normal and abnormal camper operation.
- The ability to disconnect the cab from the camper for long drives during daylight. The will allow the intelligent GoPower Solar Controller to charge the house batteries avoiding overcharging the house batteries using the "dumb" cab alternator.
- The ability to use all batteries for occupied camper operation (house+cab=320ah of capacity). Can be risky but with the Magnum and Jennsen battery alarms you should never totally discharge all the batteries. In the worst case given the design of the system all you need is enough juice to start the generator to bring everything back to life including the cab to start the engine.
- The ability to drive the camper in the event of an alternator failure. Between the cab/house house batteries and the solar system there should be no problem driving the camper indefinitely during the day time with the alternator inop.
The ability to start the MB cab engine in the event of a cab battery failure or inadvertent discharge. Simply manually combine the cab and house systems and let the camper batteries start the truck.
- During daylight hours when operating on solar alone you will hear the ML-ACR cycle on and off as either camper demand for juice and/or falling solar output conspire to bring the house batteries below 12.75v for 30 seconds. When this happens the ML-ACR automatically disconnects the cab from the camper electrical system to preserve the charge on the cab battery. When conditions change (i.e. lower camper demand and/or higher solar output) the relay will reconnect the two sides automatically.
- For long term outside storage this arrange allows both the camper and cab batteries to be intelligently charged via the solar panel controller.
So as you can see this simple device makes the entire cab/camper electrical system much more robust to deal with all sorts of planned and unplanned events that can happen on the road.
The Intellitec Isolator Relay (IIR) is a "low cost" approach to managing multiple batteries. So while the device is cheap "i.e. low cost" it seriously restricts your ability to intelligently manage the batteries and electrical system in the Unity.
The IIR connects the house electric system to the cab electrical system. The device lives under the passenger seat. It's operation is very simple, it looks for the voltage on the cab side to rise above 13.1 volts for 12 seconds, then it closes the connection between the house and cab electrical system. The device does not care what the voltage is on the house side and it provides no options to connect the two sides unless the voltage on the ignition circuit is higher than 13.3v for 12 seconds.
Given the capability of my Unity electric system (particularly the addition of up to 30 amps of solar power) I made the decision to upgrade the IIR and replace it with a Blue Sea ML-ACR Automatic Charging Relay. The ML-ACR is available on Amazon for $202.94.
The Blue Sea ML-ACR offers many advantages over the simple IIR. The ML-ACR has three modes: OFF, Automatic Combine and Manual Combine. In the OFF mode the relay disconnects the cab and camper electrical system. In the Manual Combine mode the ML-ACR connects the two electrical system with a manual switch controlled by the operator.
The magic in this device is the Automatic Combine mode. In this mode the device will automatically connect the two electrical systems any time it senses voltage on either side (cab or camper) to be above 13.5V for 30 seconds or 13.0V for 90 seconds. Likewise the ML-ACR in the Automatic Combine mode will disconnect the cab and camper electrical systems anytime the voltage on either side is below 9.6V(under voltage lockout), below 12.35V for 10 seconds, below 12.75V for 30 seconds or above 16. 2V(over voltage lockout).
In the Automatic Combine mode the ML-ACR is basically looking at voltages on both the camper and cab side of the electrical system and combines the electrical systems any time the voltages are compatible with one or the other electrical systems being charged (i.e. charger, solar or cab alternator).
Here are some images of the exchange of the IIR for the ML-ACR.
This is the passenger seat pedestal. Note the installation of the awing LED and awing in/out switch was not very "fancy".

Here is a closer look at how the switches were installed:

Here is a look at the IIR as installed by LTV in the passenger seat pedestal. The solenoid and IIR controller are mounted on the board. Note cables are just held down with aluminum tape


Here is how it looks after the Blue Sea ML-ACR is installed and the installation cleaned up:

And finally I took the opportunity to "upgrade" the switch panel on the side of the seat pedestal to include the ML-ACR control switch and provisions to monitor cab voltage when the ignition is on:

I had a Blue Sea ML-ACR in my last RV so I thought I would share some circumstances where this device provides all sorts of extra options for battery management in normal and abnormal camper operation.
- The ability to disconnect the cab from the camper for long drives during daylight. The will allow the intelligent GoPower Solar Controller to charge the house batteries avoiding overcharging the house batteries using the "dumb" cab alternator.
- The ability to use all batteries for occupied camper operation (house+cab=320ah of capacity). Can be risky but with the Magnum and Jennsen battery alarms you should never totally discharge all the batteries. In the worst case given the design of the system all you need is enough juice to start the generator to bring everything back to life including the cab to start the engine.
- The ability to drive the camper in the event of an alternator failure. Between the cab/house house batteries and the solar system there should be no problem driving the camper indefinitely during the day time with the alternator inop.
The ability to start the MB cab engine in the event of a cab battery failure or inadvertent discharge. Simply manually combine the cab and house systems and let the camper batteries start the truck.
- During daylight hours when operating on solar alone you will hear the ML-ACR cycle on and off as either camper demand for juice and/or falling solar output conspire to bring the house batteries below 12.75v for 30 seconds. When this happens the ML-ACR automatically disconnects the cab from the camper electrical system to preserve the charge on the cab battery. When conditions change (i.e. lower camper demand and/or higher solar output) the relay will reconnect the two sides automatically.
- For long term outside storage this arrange allows both the camper and cab batteries to be intelligently charged via the solar panel controller.
So as you can see this simple device makes the entire cab/camper electrical system much more robust to deal with all sorts of planned and unplanned events that can happen on the road.
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