Installing charge controller in existing system

[jasowiii]

I have a motorhome that has an existing inverter/charger, batteries, etc. I'm adding a $400 Renogy kit (4 panels, charge controller, cables).

My question is if there is an issue with connecting the charge controller (+) to the coach fuse panel input line??
The line is 2ga directly from the batt compartment about 10' away. This would make for a very easy install as the best location to mount the charge controller is next to the fuse panel. Also convenient for running to the PV input down from the roof.

Thoughts?/Concerns?

I realize this would "disconnect" the solar when if I actuate the battery disconnect switches/relays but I don't think I care.

 

[0truck0]

Electrically speaking only - it is the same thing as connecting to the battery positive terminal. I assume your "coach fuse panel input line" is directly connected to the battery positive also.
The concern is the gauge wire between the battery and your "coach fuse panel input line". You are basically just using a 10' long 2ga wire to connect the charger to the battery. Not ideal but 2ga is pretty thick wire so should not be an issue for the wire.

This is not the ideal way to charge a battery. Do NOT use the vehicle frame for the ground "wire" going to the battery. Keep both the positive and negative wires from battery to the fuse panel the same length and gauge. For charging this will matter. Frame ground is fine for running your items, just not for charging.
This also means that if there is, and there is, a frame ground to the battery neg then that will allow voltage from charger to run partly through the frame. Having charger closer to the terminals reduces any issues. IS the battery grounded at the battery and is the fuse panel grounded to the closest available place? (come to think of it my fuse block is not grounded other than that the battery is...)

You will want to put a disconnect between the solar panels and the charger also in order you can disconnect the panels FIRST before disconnecting the battery from the fuse. Ideally you do not want the panels feeding in the system without the battery there to absorb any voltage spikes. Battery also will maintain the voltage in the system more carefully.
You will want to remember to disconnect the solar first, and reconnect the solar last when disconecting and reconnecting the battery.

 

[jasowiii]

This is not the ideal way to charge a battery. Do NOT use the vehicle frame for the ground "wire" going to the battery. Keep both the positive and negative wires from battery to the fuse panel the same length and gauge. For charging this will matter.
<<<>>>>>>>
You will want to remember to disconnect the solar first, and reconnect the solar last when disconecting and reconnecting the battery.

The fuse panel is not "grounded" as far as I know. I was planning to run charge (-) to the frame. If I have to run the charge (-) wire back to the batts then I might as well run both (+/-) wires. I have battery "sense" wires that I plan to connect between the charge controller and the batteries. Would this negate the concern about using the frame? The charge controller is a Renogy Adventurer Li-30A PWM.

I will install a breaker on the PV side of the charge controller but are you saying there is a concern with the battery disconnect switches/relays? It has both a remote 12V disconnect switch (and relay) at the front door and manual disconnects (coach and chassis) in the batt compartment.

 

[HarryN]

I don't really understand why it would be a problem.

Not "ideal" due to the long wire runs in the RV, but not bad.

( 20 amp fuse ) x ( 12 volt ) ~ 200 watts per channel is the main limitation.

If you have not purchased the renogy stuff, maybe buy a bogart solar charge controller instead.

 

[jasowiii]

( 20 amp fuse ) x ( 12 volt ) ~ 200 watts per channel is the main limitation.

If you have not purchased…

Ya lost me. 200?

I did buy it already

 

[HarryN]

Ya lost me. 200?

I did buy it already

No problems, just relax. It is just a matter of planning and implementation details.

Take a look at the diagram. All mobile systems are more or less the same, just minor differences in implementation details.

So I use that diagram a lot in my own work in 24 volt, but 12 volt is more or less similar.

Imagine that you want to feed all of the chargers into the power system through the fuse block "channels". In other words, the output of the solar charger enters by going through an individual fuse in the fuse block.

That fuse size is limited to 20 or 30 amps, depending on the fuse block. All of the ones in your existing setup are 20 amps or under, so doing it that way limits it to ~ 200 watts per each fuse position.

If you use 2 fuse positions, then you can double this to ~ 400 watts by running a 10 awg wire to each fuse position.

Alternatively, pretend that your solar charge controller is one of those fuse blocks in the diagram, and just add a breaker in between your solar charge controller and that 2 awg wire to make it all safe. Wire to the main 2 awg wire at your existing fuse block.

If you purchased a renogy mppt controller, consider to send it back and buy something that actually works. Those things have a very large standby power draw that rivals many inverters.

You can try it if you like and see if it works well enough for you, but in the PNW, there is a reasonable risk that it will consume more power than it generates.

 

[HRTKD]

Before you flip the battery disconnect switch, turn off the PV input to the solar charge controller.

Then when turning the system back on, battery switch first, then PV switch.

A lot of PV systems bypass the main distribution panel as well as the battery disconnect and go straight to the battery. That way you can disconnect all the loads but still charge the battery.

 

[0truck0]

I think he is talking about running power to the main positive on the fuse block, not an individual fuse slot.
( I have a friend who bought a used trailer and someone "fixed" the bad positive cable issue from battery by connecting the electric jack cable to the battery instead of using the main battery feed cable. That did power the jack, and also sent battery power back to the fuse block via an individual fuse slot; the jack's slot, but as mentioned did limit the entire trailer to 20 amps at a time. So far it has been working but he only uses lights and a water pump)

Do disconnect the solar first and connect it last. 99% of the time if you do not then it might not even matter, but this is a safe practice to save your charge controller damage. Some /few can, some can not run safe without a battery, but assume that all can't.

I'm not sure I am right on this, please correct me if wrong.... I do not think you ground the DC fuse block/panel since you are planning to charge battery from there. The battery is grounded and you can ground your end items, but grounding the panel means current will run through the frame also - you want current from the solar charger to run down a pair of wires only. If you run charger straight to battery then you can ground panel all you want.
So, yes, everything will function if you charge through the frame ground but for reasons given all across the forum post this is not the best practice.

 

[mikefitz]

Any battery charger or solar charge controller charge profile relies on accurately monitoring true battery voltage. If the installation introduces volt drops between charger and battery, the charge process is compromised to some degree.
To avoid this issue, in RV installs, I recommend Victron charge controllers together with a Victron Smart Shunt battery monitor or a Victron Smart Battery Sense. The Victron Smart Shunt or Battery Sense , installed close to, and connected to the battery, report battery volts and temperature th the Victron controller, thus allowing the Victron charge controller to be installed in a convenient location, perhaps some distance from the battery.

 

[jasowiii]

Update in case anyone decides to install in my model and year.
I decided that since I was running batt V sense and temp all the way to the batt compartment I might as well run batt charge wires.

I ran into difficulties fishing the wires from the fridge area to the batt compartment. I decided to mount the charge controller in the TV cabinet in the rear bedroom, almost directly above the batt compartment. The charge controller has a blue tooth add on, so I should be able to monitor via the app.

I plan to penetrate the roof a couple inches inboard of the roof cove seam. This model year tiffin DOES NOT have a one piece roof. I'll call it a hybrid one piece with coves. The roof cove contains cables running to the front of the coach. Based on research, I believe the A/C and heater lines run down the center. So hopefully I don't hit anything...

Thanks for the help!