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.

[mike-s]

red31 wrote:
As stated in MS manual, the voltage drop does not reduce as the batt fills unless there is less power potential from the panel from heating or less sun.

Either you're unclear on the concept, or simply making things up. The manual says no such thing, because it would incorrect.

[Almot]

jplante4 wrote:

red31 wrote:
"Locate the controller within 10 ft (3 M) of the battery bank."

Is that based on the recommended wire gauge between the controller and battery? If so, you can up the gauge and go longer.

The OP never told controller brand, or MPPT/PWM, or panel size. IMO, hard to suggest anything constructive at this point.

[TurnThePage]

My mppt charge controller is in the same cabinet, and is wired directly to the output of the converter, which is a straight run to the batteries. It's been between my two 75 watt panels and the batteries for years, and has taken great care of them. Unless I become a fulltimer and need to eek out every little ounce of power, I will stick with this tried and true method. I do have switches and fuses in between the controller and panels, and batteries.

[time2roll]

Yeah if you mount the controller between the water heater and the electric panel while the battery sits outside... that will cause charging and float voltages to be artificially low.

[red31]

charge controller do temp compensation, keep the controller near the battery for proper temp compensation or find one with remote temp and remote v sensors. Easier and cheaper to stay near the battery.

Charge controllers do not prevent undercharging, poor installs make undercharging worse.

Glad you agree what MS puts in manuals.

BTW, that controller won't accept 8g

As stated in MS manual, the voltage drop does not reduce as the batt fills unless there is less power potential from the panel from heating or less sun.

[2oldman]

It's Sunsaver Morningstar. Subsidiary? Nothing nefarious about the link.

[mike-s]

red31 wrote:
https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/SS3.IOM_.Operators_Manual.01.EN_.pdf

Fail. That's not Morningstar, and I'm not clicking on a link hosted by "2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com".

Oh, and if you look at the _real_, and current, Morningstar manual for the Sunsaver, http://support.morningstarcorp.com/wp-content/uploads/2014/07/SS-3-IOM_v3.3_WEB.pdf , the phrase in context is:

The unit should be located in the same ambient temperature as the battery.
Locate the controller within 10 ft (3 M) of the battery bank.

The SunSaver does not support remote battery temperature sensing, and it's clear that's why they suggest (should, not must) it be mounted close to the battery. As I said, having the controller adjust for the battery temperature is more important than worrying about voltage drop, which becomes minimal as the battery gets full. Typical temperature adjustment is 0.03 V/degree C, so a 10 degree (18F) change in temperature makes more difference than a 2% voltage drop, even at full current. The SS maxes out at 20A, so that's the drop for a 29 foot one-way run of 8 gauge copper.

[red31]

mike-s wrote:

red31 wrote:
A Morningstar manual might suggest 10' MAX from controller to batt.

They might, but they don't.

But they do. Let me spoon fed it to you.

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/SS3.IOM_.Operators_Manual.01.EN_.pdf

[mike-s]

red31 wrote:
"Locate the controller within 10 ft (3 M) of the battery bank."

Are you trying to prove something? If so, you should provide a proper source. That phrase is nowhere to be found in the manuals for the Morningstar Prostar (gen3) or Prostar MPPT controllers.

[red31]

jplante4 wrote:

red31 wrote:
"Locate the controller within 10 ft (3 M) of the battery bank."

Is that based on the recommended wire gauge between the controller and battery? If so, you can up the gauge and go longer.

That may be so for a different controller from MS, Step 1 is locating the controller and the one I quoted states what I quoted, I believe for temperature reasons but they wrote what they wrote. Later, step 3 suggests using their 2% chart for wire sizing, one should also consider the max wire size limit of the controller.

Another controller limits distance to 3M without the voltage sensor! and goes on to state:

'Generally accepted wiring practice is to limit voltage
drops between the charger and the battery to 2%.
Even properly sized wiring with 2% drop can result in
a 0.29 Volt drop for 14.4V charging. voltage drops
will cause some undercharging of the battery. The
controller will begin Absorption or limit equalization
at a lower battery voltage because the controller
measures a higher voltage at the controller’s terminals
than is the actual battery voltage. For exAmple, if
the controller is programmed to start Absorption at
14.4V,when the controller “sees” 14.4V at its battery
terminals, the true battery voltage would only be
14.1V, if there is a 0.3V drop between the controller
and battery"

[jplante4]

red31 wrote:
"Locate the controller within 10 ft (3 M) of the battery bank."

Is that based on the recommended wire gauge between the controller and battery? If so, you can up the gauge and go longer.

[red31]

"Locate the controller within 10 ft (3 M) of the battery bank."

[mike-s]

Almot wrote:
There should be 2 fuses: a controller fuse close to controller, and the battery fuse close to the battery.

Yep, because both the controller and the battery can source current, both need a fuse or breaker nearby.

red31 wrote:
A Morningstar manual might suggest 10' MAX from controller to batt.

They might, but they don't.

[Almot]

OP: Battery fuse protects trailer wiring from battery short. If it blows, it means you already don't have a battery.

There should be 2 fuses: a controller fuse close to controller, and the battery fuse close to the battery. With a Pos buss in between.