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Old 05-15-2020, 01:42 PM   #1
3 Rivet Member
2016 30' Classic
Sammamish , Washington
Join Date: Feb 2010
Posts: 113
Factory Installed Solar Upgrade

I am currently in the process of upgrading the Atkinson solar controller in my 2016 Classic. The reason for this upgrade is the mismatch in the Atkinson charging parameters and the parameters required by my LifeLine batteries. Most flooded cell, AGM and GEL batteries require a three stage charging profile, the Atkinson controller only has one stage, sort of bulk charging. Furthermore, the Atkinson controller uses the controller location for temperature compensation, not the battery temperature. In my coach, this has resulted in my batteries never being charged more than 95% (with and without the Atkinson jumper being clipped).

The equipment I have chosen for this upgrade are the Victron MPPT 100/30 SmartSolar Charge Controller and the Victron 500A SmartShunt. I have chosen this equipment for the following reasons. First, the SmartSolar charge controller provides three stage charging that can be matched to the LifeLine batteries. Second, the SmartShunt allows me to monitor the battery, the charge controllers only allow me to monitor the photovoltaic system. Finally, both the charge controller and the shunt can be programed and monitored by Bluetooth. The advantage here is that I do not have to fish a signal cable to a location where the “monitor” is visible. For those of you that are unfamiliar with the Classic, the Converter/Electronic Kill Breaker Panel is located between the sofa and the front wall of the trailer while the “monitor” is located above the range.

The installation of the SmartSolar charge controller is straightforward, remove the Atkinson controller and add the SmartSolar charge controller. In this case, because of its size, I will mount the charge controller next to the Kill Breaker Panel. I will also add a battery switch on the positive lead coming from the solar panels and a 30A breaker on the positive lead going to the positive bus on the Kill Breaker panel. The switch and the breaker allow for future maintenance and upgrades and they will be mounted on the Kill Breaker panel.

The installation of the SmartShunt is a bit more complicated. Victron requires the shunt be located in a dry location because of the electronic circuit board on the shunt. Since the battery box is located on the A-frame on the front of the trailer it is not a “dry” location. In addition, there have been some reports of intermittent Bluetooth communication through the steel battery box and the trailer shell. For this reason, I have chosen to mount the shunt on the Kill Breaker panel. In order to do this, I will have to do a bit of rewiring. First, I need to pull the 6 AWG negative battery cable going from the battery to the ground bar on the Kill breaker Panel. This cable will be “replaced” with a 1 AWG cable. This new cable will go from the battery to the battery side of the shunt. The 6 AWG cable will be shortened and go from the load side of the shunt to the ground bar on the Kill Breaker panel I will also need to fish the temperature sensor wires from the shunt to the battery box. The reason for the increase in cable size is that my trailer also has a 1000W invertor with 4 AWG cables that go directly to the battery box. Therefore, I will need to reroute the negative cable from the inverter to the load side of the shunt (all loads must go through the shunt to properly monitor the battery).

This upgrade will allow me to add two panels to the roof in a series/ parallel configuration and not overload the existing 10 AWG wires going to the solar controller. I could also add portable panels but that is another story.

Any thoughts or suggestions would be appreciated.
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Old 05-18-2020, 09:40 PM   #2
3 Rivet Member
2016 30' Classic
Sammamish , Washington
Join Date: Feb 2010
Posts: 113
I have decided to make a two changes. First, I am going to going to increase the breaker size on the output of the 30A controller to 40A. The reason for this is that a number of schematics on the Victron web site show a 40A with their 30A charge controllers.

The second change is a bit more academic. Probably the best way to determine the gauge of the cable from the negative terminal of the battery to the load side if the shunt is to use the Voltage Drop Index (VDI) formula:

VDI = ( current * length ) / ( % voltage drop * voltage)

In my system:
maximum current - 150A
cable length - 6’
voltage drop - 2%
voltage - 12V

VDI = ( 150 * 6 ) / ( 2 * 12 )
VDI = 37.5

This suggests that the voltage drop on my system would be slightly more that the 2% that I have chosen. Therefore, I have chosen to use one size, larger, 1/0 AWG.

If you cannot find a table with VDI, you can convert VDI to mm2 by multiplying it by 1.1
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Old 05-19-2020, 12:21 PM   #3
3 Rivet Member
2016 30' Classic
Sammamish , Washington
Join Date: Feb 2010
Posts: 113
Originally Posted by PJohnson View Post
… from the negative terminal of the battery to the load side if the shunt ...
Should read … form the negative side of the battery to the battery side of the shunt ...
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Old 05-19-2020, 12:27 PM   #4
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2018 27' Globetrotter
Apollo Beach , Florida
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You want to have a breaker that is one size larger than the solar controller output, and wiring that will handle the increased breaker size. I put a 40A on my Victron 100/30 with 6 gauge wiring and a 60A on my Victron 100/50 with 6 gauge wiring.
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Old 05-19-2020, 03:43 PM   #5
3 Rivet Member
2016 30' Classic
Sammamish , Washington
Join Date: Feb 2010
Posts: 113
I mentioned the increase in breaker size in the second post. I was not able to find any documented reference to charge controller breaker size on the Victron website.

I would have edited the first post but I was unable to find a way to edit it. Then, in my second post, i needed to edit it and again could not, hence my third post. :-)
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