Can I connect my charge controller to my panel?

[JoshInReno]

Dear lord I have searched and googled, but I cannot find an answer.

I am adding a small solar system to my trailer (I have done previous systems in previous trailers) and rather than connecting my controller to the batteries (difficult wire run) I'm wondering if there is a spot on my breaker panel that I can wire to?

I'll run the wires to the batteries I necessary but I'm thinking their might be a shortcut here.

Thanks in advance.

[time2roll]

What does the manual say? PWM or MPPT? How many watts?

[pianotuna]

The reason for a fuse between the battery bank and the controller (which should be close to the battery) is to prevent a catastrophic failure. I.E. a short in the wire. Don't forget batteries were at one time used for welding.

In other words the fuse has nothing to do with protecting the controller.

Optimistic Paranoid wrote:


If you run the controller directly to the battery, through it's own fuse, pretty much the only way that fuse can blow is if something has gone wrong with the controller. In other words, most likely the controller is ALREADY toast by the time the fuse blows, and you're just keeping the wire from overheating and starting a fire.

[Optimistic_Para]

mike-s wrote:
Check the controller manual. Some of the "advice" here is dangerous BS. For instance, Morningstar, Renogy, Midnite Solar (and I'm sure most manufacturers) all advise that a fuse or breaker be installed in every circuit (battery, solar, load). If a properly sized protective device opens, it could have saved you from more serious issues than a damaged controller.

I'm sorry. Apparently I wasn't making my thinking on this subject clear.

If you run the controller directly to the battery, through it's own fuse, pretty much the only way that fuse can blow is if something has gone wrong with the controller. In other words, most likely the controller is ALREADY toast by the time the fuse blows, and you're just keeping the wire from overheating and starting a fire.

If you run the controller to your fuse panel, and thus through the main fuse between that battery and the panel, then any problem ANYWHERE in the electrical system that causes the main fuse to blow will throw you into a situation where the controller suddenly finds itself with no batteries, which will almost certainly damage a good controller that wasn't having any problems of it's own.

[red31]

A Morningstar manual might suggest 10' MAX from controller to batt.
Lower and lower sunlight tapers current, but a pwm controller does not, it sends FULL blast of current in pulses, their width or time averaged over time may be considered as tapering current but when power is sent to the batt it is all that is available, all or none. If you turn your 100w light on and off for equal time it is on for 100w when it is ON. the average over time may be 50w.

[Almot]

MrWizard wrote:

Never disconnect the battery

What Mr Wiz was really telling (I think) was - not to disconnect the battery while controller is still connected to the panel. Disconnect the panel input from controller first (or, indeed, cover the panel).

Strictly by the book, controller should have a fuse after the controller, then - Pos buss, and from there - Pos lead to the battery, with another fuse close to the battery.

With a small panel you don't need any fuses before controller, only "some" disconnect - to disconnect the panel if you plan to remove the battery.

[mike-s]

Check the controller manual. Some of the "advice" here is dangerous BS. For instance, Morningstar, Renogy, Midnite Solar (and I'm sure most manufacturers) all advise that a fuse or breaker be installed in every circuit (battery, solar, load). If a properly sized protective device opens, it could have saved you from more serious issues than a damaged controller.

The wiring length/voltage drop won't keep your battery from getting a good charge. You will lose a bit of efficiency, but the battery will charge fully (the current and therefore the voltage drop will taper off as the battery gets full). If it's a PWM controller, it really doesn't make any difference whether the controller is near the panel, the battery, or somewhere in between. Using a controller lacking remote battery temperature sensing is a bigger concern than voltage drop as far as proper battery charging goes.

Wiring to the battery connection at your converter is fine. You can check to see what gauge wire goes from there to the battery, and you want to use the same or thicker from the controller to there, along with an appropriate fuse/breaker near the controller.

Also, it's going to be just the charging current going to the battery - any going to devices gets distributed straight from the panel, so that eliminates some of the inefficiency due to voltage drop you would have if it were wired direct to the battery.

[JoshInReno]

You guys make some excellent points that I hadn't considered. I'm glad I asked before going through with it.

Thanks for saving me a headache!

[Optimistic_Para]

Is there not a fuse between the battery and the fuse block? If so, and that fuse blows, that could blow your controller.

[Almot]

How "small" panel? Converter wires are probably #12, so... you can wire controller to converter output, if panel is 50-60W. 100W panel (which is still "small", in my books) will work fine most of the time, but sometimes will cause too much voltage drop (6-8ft to converter + another 15-20ft to battery), and then your battery won't get a good charge.

This all should concern you less than the fact that controller-converter path usually doesn't have easy and/or obvious means to disconnect the controller before disconnecting the battery. If you forget, controller might get a heart attack - or it might survive. Better not to take chances.

You might want to run the numbers here: Voltage drop

[MrWizard]

Can you do it?
Yes with a few gotchas
Never disconnect the battery
You will have to disconnect or cover the solar panel up
Before even cleaning the battery posts, same rules with direct run to battery
But easier to forget when the wires are some place else
It may not charge as well, as with a direct connection to batteries
Depending on the wire gauge involved

[JoshInReno]

Flyfasteddie wrote:
If you can get to your converter you can tie in to the battery connection there.

My solar panel is right above my converter which is about 15' horizontal from the battery. Instead of running additional cable to the battery I just ran the solar controller output to the lugs that connect the converter to the battery.Instead of running additional cable to the battery I just ran the solar controller output to the lugs that connect the converter to the battery.

You'll lose a few tenths of a volt (depending on how many watts you're pushing and how large the existing wire is) but in my case it wasn't worth running the extra wire.

Thank you - I think you stated a better way of stating the question that I am asking.

The wires from my batteries connect to my electrical panel. Can I connect the output from my controller to where the wires from my battery connect to the circuit breaker panel or do I need to run them directly to the batteries?

[time2roll]

If you have an empty branch circuit in the 12 volt distribution panel with proper amp rating then it will work.

Many controllers require a battery connection at all times if the panels are connected or the controller can be damaged.

Depending on power and connections you will get better performance with the controller close to the battery.

[2oldman]

JoshInReno wrote:
I'm wondering if there is a spot on my breaker panel that I can wire to?

I don't think your 12v panel has breakers, but if you want to connect somewhere that connects directly the batteries (like the converter connection) that would be ok.

[Flyfasteddie]

If you can get to your converter you can tie in to the battery connection there.

My solar panel is right above my converter which is about 15' horizontal from the battery. Instead of running additional cable to the battery I just ran the solar controller output to the lugs that connect the converter to the battery.

You'll lose a few tenths of a volt (depending on how many watts you're pushing and how large the existing wire is) but in my case it wasn't worth running the extra wire.

[pianotuna]

Bad idea as most controllers want the battery to be connected. If you go to the dc power distribution panel and then use the battery disconnect the controller won't be connected either.