More solar questions

ChrisK

I got a break in the temps here in AZ (only in the low 90s) so I just installed my solar system (mostly). I installed two flexible 100w panels on the roof (one in front of the vent and one behind) and a Victron mppt 75/15 bluetooth solar controller in the tub. First of all, what wattage should it normally be showing? I know it depends on sun coverage, etc but what should I be seeing on average. I'm seeing about 103 right now with the Arizona sun mostly on the rear panel. 
Second, I know its bad to leave a battery plugged in to shore power for too long, same thing for solar? I have it set up so I can turn the battery off with the main switch to the camper and I can turn off the solar panels to the controller. Battery is a 12v AGM (Optima brand). Yes, I know I should have more battery but for now, its all I have. 
BTW - Love the Victron bluetooth controller so far. No need to install a panel in the camper. Just connect via smartphone. I can check status from inside or outside the camper. That is very important for someone lazy like me that doesn't want to get up out of my camp chair. 
Next short term plan is for a small inverter so I can charge my computer or my RC equipment and a couple more 12v outlets for charging smart devices. 

Edit: Ignore the first question. I figured out that the app is not showing total generated watts, but rather watts being used at that time. Their manual is not very good.

ColoradoJon

Well, it's technically not 'bad' to leave your battery plugged into shore power, unless the converter/charger is not capable of maintenance charge.  If you have the factory installed WFCO 8735 or a external smart charger you can leave the battery to charge indefinitely.

Same goes for your solar charge controller.  The Victron that you have chosen is a multi-stage adaptive charger, so you can leave it connected to your batteries for as long as you want.

Ratkity

ColoradoJon said:

Well, it's technically not 'bad' to leave your battery plugged into shore power, unless the converter/charger is not capable of maintenance charge.  If you have the factory installed WFCO 8735 or a external smart charger you can leave the battery to charge indefinitely.

Same goes for your solar charge controller.  The Victron that you have chosen is a multi-stage adaptive charger, so you can leave it connected to your batteries for as long as you want.

Adding one caveat to folks reading this and they have an acid-flooded battery (and not the new AGMs). Flip the battery main and disconnect the solar at the beginning of the season, carefully wiggle the two caps off the battery (or each battery)  and check the water level. I only have to add 1-2 tablespoons of distilled water per cell (don't use regular tap water or spring water). It's not much, but will increase the life of your battery!

A squirt bottle helps to add the water and I use a tablespoon with distilled water poured in a cup. If you accidentally overflow a cell, don't touch it. It has sulfuric acid in it. Finish up with the other cells first and close the lids tightly. Then clean it up with a piece of shop towel or paper towel with gloves on and put it in baking soda and water mix. It neutralizes the acid into water and salt. Dab a bit of the baking soda mixture on the top of the battery to neutralize any acid that may have spilled from an overflow. You'll see a white residue. That's ok. You can wipe it off with damp paper towel. 

After adding water, you can let the battery sit with no loads overnight to let the chemicals mix or go ahead and plug in shore or solar power. 

Sawtooth

@ChrisK ,

What is your peak power with your setup?  And which 100W panels did you go with?  I have a similar setup with the same controller.  On the controller, did you use the "Load" output terminals or connect directly to the battery?  I've noticed that when the controller is hot that the Load output sometimes won't enable.  If I remove the fridge fuse I can get it to enable.  I'm curious if you've seen something similar.  The controller manual mentions that if the in rush current is too high on the load output that it may not enable, so I'm not too surprised, but if your not seeing something similar than maybe I'll look into it more.

pthomas745

An FAQ about solar controllers and comments about what the load function is.

https://www.solar-electric.com/learning-center/batteries-and-charging/solar-charge-controller-basics.html

ChrisK

Sawtooth said:

@ChrisK ,

What is your peak power with your setup?  And which 100W panels did you go with?  I have a similar setup with the same controller.  On the controller, did you use the "Load" output terminals or connect directly to the battery?  I've noticed that when the controller is hot that the Load output sometimes won't enable.  If I remove the fridge fuse I can get it to enable.  I'm curious if you've seen something similar.  The controller manual mentions that if the in rush current is too high on the load output that it may not enable, so I'm not too surprised, but if your not seeing something similar than maybe I'll look into it more.

I connected the battery to the "Batt" terminals. I'll connect the inverter to the load terminals when I get one. This is per the manual. Since I'm not using the Load terminals at this point, I turned it off in the software.

ChrisK

I stand corrected. Per the article linked above,  won't be running my inverter off the Load connection.

"What is a Load, or "Low Voltage Disconnect" output?

Some controllers also have a "LOAD", or LVD output, which can be used for smaller loads, such as small appliances and lights. The advantage is that the load terminals have a low voltage disconnect, so it will turn off whatever is connected to the load terminals and keep from running the battery down too far. The LOAD output is often used for small non-critical loads, such as lights. A few, such as the Schneider Electric C12, can also be used as a lighting controller, to turn lights on at dark, but the Morningstar SLC lighting controller is usually a better choice for that. Do not use the LOAD output to run any but very small inverters. Inverters can have very high surge currents and may blow the controller.

Most systems do not need the LVD function - it can drive only smaller loads. Depending on the rating of the controller, this may be from 6 to 60 amps. You cannot run any but the smallest inverter from the LOAD output. On some controllers, such as the Morningstar SS series, the load output can be used to drive a heavy duty relay for load control, gen start etc. The LOAD or LVD output is most often used in RV & remote systems, such as camera, monitor, and cell phone sites where the load is small and the site is unattended."

ChrisK

pthomas745 said:

An FAQ about solar controllers and comments about what the load function is.

https://www.solar-electric.com/learning-center/batteries-and-charging/solar-charge-controller-basics.html

Thanks for posting that link. Very informative.

ScottG

Good info @pthomas745. I always thought the load terminals were for running something from the panels with connecting to a battery. Just a silly guess on my part however, as I've never used them so never gave them more than a passing thought.

Now I'm curious if anybody (@Sawtooth, maybe?) actually uses the load terminals on their controller, and if so, for what?

pthomas745

The advantage of the load output is they can be set on a "timer" for your remote power needs.  At least, that is what I gather from the comments on them.  Haven't dug deep enough to find a good example (with pictures!).  Sounds like a test project for a rainy day.

Sawtooth

@ScottG I do use the load terminals per the user guide for the charging features it brings.  It is also nice to see separate readings in the phone app for the load current and the battery current.

@pthomas745 Thanks for the FAQ, it was an interesting read.  Keep in mind that it is a general FAQ that is not specific to this particular controller.

From the Victron user manual for the MPPT 75/15

"1.4 Load output Deep discharge of the battery can be prevented by connecting all loads to the load output. The load output will disconnect the load when the battery has been discharged to a pre-set voltage. Alternatively, an intelligent battery management algorithm can be chosen: see Battery Life. The load output is short circuit proof. Some loads with high inrush current can best be connected directly to the battery. If equipped with a remote on-off input, these loads can be controlled by connecting the load output of the controller this remote on-off input. A special interface cable may be needed, please see section 3.7. Alternatively, a BatteryProtect may be used to control the load. Please see our website for specifications."

Sawtooth

FYI, I gave up on using the load output and have switched to drawing directly from the battery.  The load output was very finicky even when I pulled the fridge fuse.  Often it simply wouldn't enable into the load.  Sometimes I could get it to stay enabled if I started with the T@B connected to AC then disconnected the AC, but if I switch the battery into the load with nothing powered up, it frequently wouldn't enable.  

It's too bad, the load port monitoring and charge protection would have been nice features.

@ChrisK any updates on the average peak wattage you're getting from your solar panels?  It seems like I get into the upper 60s in wattage best case for each panel, but I haven't had many opportunities to test them.

ChrisK

I barely see 5w but the camper is just sitting in the side yard for now. The first trip that will test the solar is this weekend. No hookups at all. We'll see how it does. This campground has more trees than most AZ campgrounds though so we are taking the generator too as a backup.