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Please critique my proposed Van solar setup

8milimeter

8milimeter

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Joined
May 25, 2020
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54
SolarWiring.jpg


I would like to monitor the system, any suggestions on shunts and displays would be appreciated.
 
Might just be a diagram thing but the solar charge controller should be connected to the same negative terminal as the inverter.
 
negative and positive busbars would make things easier to see.
 
Depending on distance between the dc2dc charger and your alternator 6 awg might be a bit light.

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.
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Main fuse should be 125 amps minimum to cover the inverter.
245 amps is the max fuse size for the wire.

Good drawing and design.
 
Suggest a shunt based battery monitor.
Its not absolutely necessary but quite useful.
 
should have a fuse between the alternator and the dc2dc charger.
 
AIMS low frequency 1250watt inverter/charger

I would like to monitor the battery charge level and get alerts for potential problems.

I was only going to get the 20amp dc to dc charger. Thought 6 awg was enough

Thanks for all the input, will adjust diagram and resubmit.
 
8milimeter said:
View attachment 15996


I would like to monitor the system, any suggestions on shunts and displays would be appreciated.
Click to expand...

I am wiring in a Victron Battery Monitor to monitor the load via the negative lead on the Lifepo4 battery bank. Given my Victron BMG 702 has bluetooth, I will have the same capability on my smartphone. Also, the AIMS solar charge controller has a digital display to view the system health. The BMS on my battery bank has a bluetooth app that I can use to monitor the health across the 8 3.2v, 100ah cells.

I have purchased a pair of inexpensive monitors (AC monitor and a DC monitor... I may add more of them) that I may install at key points in the system when and if I need to break monitoring of the POWER and LOAD curcuits further; perhaps if I need to pinpoint where I may have too much LOAD.

My inverter will be connected to my solar charge controller via the LOAD connections. Inverter will not be connected to my set of Lifepo4 batteries.

The only circumstance where I may have a set of batteries (not the batteries powering solar) connected to my inverter would be if I installed a 50amp selector cylinder switch between my bus batteries (24v system - IN), the solar charge controller (24v system - IN) and the inverter so that I may have the option of powering my House systems while I am tooling along on the road. However, I would also need to ensure that I have shut my load switch off between the solar charge controller and my inverter to avoid conflicts as I do not currently plan to use automatic transfer switches; just manual switches.
 
That looks a lot like what I'm planning as an upgrade to my class-C, so I'm very interested in additional feedback.
A couple questions I have are 1) the advantage of the DC to DC vs using a simple isolator? 2) Does the shunt on the + vs shunt on the - make a difference? I'm sure that these questions have been answered elsewhere, so I'll go search...
 
cwstnsko said:
A couple questions I have are 1) the advantage of the DC to DC vs using a simple isolator?
Click to expand...

A simple isolator is not appropriate for lifepo4 house batteries.
Lifepo4 batteries have such a low internal resistance that they can draw enough current to hurt themselves.
Luckily usually the alternator burns up first.
A dc2dc charger regulates and normalises both current and voltage to do proper charging of your house batteries without undue strain on your alternator.

cwstnsko said:
2) Does the shunt on the + vs shunt on the - make a difference? I'm sure that these questions have been answered elsewhere, so I'll go search...
Click to expand...

Shunts typically go an the negative leg.
There are "high side" shunts but I understand they cost more money.
Electrodacus uses high side shunts.
I can't give you a specific link because the website colour scheme hurts my eyes like welding flash.
 
smoothJoey said:
A simple isolator is not appropriate for lifepo4 house batteries.
Lifepo4 batteries have such a low internal resistance that they can draw enough current to hurt themselves.
...
Shunts typically go an the negative leg.
...
Click to expand...

That makes sense, Thanks
I just ordered a set of 2 UT 1300s on the Costco deal, so my design just went from AGM to LiFePO4. I'll probably lean towards one of the MPPT solar charge controllers with the DC-DC built in.

The shunt I ordered appears to be designed for the negative side. I was just curious that 8milimeter showed his on the + leg and I hadn't seen that in my search for a low-cost battery monitors
 
cwstnsko said:
I'll probably lean towards one of the MPPT solar charge controllers with the DC-DC built in.
Click to expand...

Thats not a common combination.
Do you perhaps mean an all in one.
inverter/charger/solar charge controller?
 
As mentioned, shunt goes on the negative side for the Victron BMV and a red wire runs from the shunt to the most positive battery post. I would also think about a switch from the panels to the charge controller as a way to disconnect the panels from the SCC.
 
smoothJoey said:
Thats not a common combination.
Do you perhaps mean an all in one.
inverter/charger/solar charge controller?
Click to expand...

I should probably start my own thread so as not to distract from the design/diagram that the OP is fine tuning.

The two controllers I've come across so far that combine MPPT solar with a DC-DC charger in one unit are the Renogy DCC50S and the KISAE DMT1250.

Given that my current converter is an older PD model and the inverter I have is a modified sine wave, rather than pure sine wave, perhaps I should explore whether or not an all-in-one makes sense.

I've been tending towards using the components that I have and keeping investment minimal since the RV I'm fitting this to is likely to be replaced with a newer unit in the next few years. My current converter does have the Charge wizard button to force it to Boost Mode (14.4V), so I've been treating any converter upgrade as optional, and I figure that the 1500W modified sine wave inverter that I bought years ago, but never installed, is already paid for, so I may as well use it. :)
 
cwstnsko said:
I should probably start my own thread so as not to distract from the design/diagram that the OP is fine tuning.

The two controllers I've come across so far that combine MPPT solar with a DC-DC charger in one unit are the Renogy DCC50S and the KISAE DMT1250.

Given that my current converter is an older PD model and the inverter I have is a modified sine wave, rather than pure sine wave, perhaps I should explore whether or not an all-in-one makes sense.

I've been tending towards using the components that I have and keeping investment minimal since the RV I'm fitting this to is likely to be replaced with a newer unit in the next few years. My current converter does have the Charge wizard button to force it to Boost Mode (14.4V), so I've been treating any converter upgrade as optional, and I figure that the 1500W modified sine wave inverter that I bought years ago, but never installed, is already paid for, so I may as well use it. :)
Click to expand...

If you go with the KISAE DMT1250 please give us your review.
 
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