Solar Charger/controller

[FlyFishinRVr]

Originally Posted by wachuko

That is strange... solar cables can only go in one way. And yes... I remember running into the same thing... Airstream had them labeled incorrectly but connected correctly... made for a few minutes of me being puzzled by it...

Well....yes and no. If we're talking about more than one panel, then they can be wired more than one way, because you can wire them in series or in parallel. If they're in series, you'll have the positive wire of one panel connected to the negative wire of the next one, and so on. If they are wired in parallel, you'll have all the negatives connected together, and all of the positives connected together. Which way it's done can make a BIG difference in many things, like wire size needed and MPPT controller efficiency. Personally, for our small coaches, I recommend a series connection due to how MPPT charge controllers work, plus that connection method doesn't require re-wiring from the panels to the charge controller to handle the larger current produced by a parallel connection (remember, current in parallel adds, voltage in series adds).

So, back to Dena's quandary regarding "improperly connected solar panels". Ummm.....honestly, your installer sounds like a nitwit. Sorry, I'm just calling it like I see it. If they don't know the difference between series and parallel solar panel installation and how it impacts performance, you need to find someone else to finish this job because if they don't know THAT, heaven only knows what else they've messed up. Better safe than sorry......

[Land Sailer]

Ha! Yes, I'm sure there is a nitwit in there somewhere! Airstream installed all the panels; another tech installed the new controller/charger and BMI. Not sure who deserves the nitwit award.
Leaving the frig on overnight and will check battery levels tomorrow morning. I'm getting hopeful that everything will actually work as it is supposed to. Sure hope I'm not disappointed. If things don't go well you might read about me in the newspapers.
Wondering. If a panel or panels were wired in reverse, positive/ negative reversed, could that account for panels pulling battery power rather than supplying power to the batteries?

[FlyFishinRVr]

Originally Posted by Dena m

Wondering. If a panel or panels were wired in reverse, positive/ negative reversed, could that account for panels pulling battery power rather than supplying power to the batteries?

I don't believe the Victron charge controller will allow back-charging into the panels, but it's certainly possible with lesser controllers (*cough* Atkinson *cough*).

Keep in mind that if you were using your coach at all (fridge, radio, lights, propane switch on, water pump switch on, etc.) your house batteries will be drawn down. If your solar wasn't working for some reason and you had no other charging source, then certainly you would see the voltage on the house batteries slowly but surely go down.

[Land Sailer]

The behavior of the batteries has been odd. Batteries were surprisingly low when I took it out of indoor storage. I left it overnight with the frig on. (Testing, testing) seemed like the more sunlight it received, the lower the batteries would go. A reverse charge! That's when voltage readings were low 8s.
Tech says the only wire he changed was on one of the panels. He said after that the solar system charged the batteries resulting in amazingly high readings. (Best ever! That makes me think I've never had solar charging.)

Let you know tomorrow.

[FlyFishinRVr]

Originally Posted by Dena m

Batteries were surprisingly low when I took it out of indoor storage. I left it overnight with the frig on.

If your batteries were reading 11.4v and you still left your fridge on, you were taking basically dead batteries and continuing to flog them (referencing the "beating a dead horse" analogy).

If you look at the chart that I posted previously, you NEVER want your batteries in the red. If you look at the chart Uncle Bob posted, 12v is a very good reading to use as THE LOWEST YOU SHOULD RUN YOUR BATTERIES.

AGM batteries are funny beasts. If you take them below 50% of their rated charge (i.e. below about 12v), you will damage them, reducing their useful life. The more you take them below that number, the more damage is done. You could end up reducing the useful life of your batteries from 5+ years to less than 1 year. At over $300 each for equivalent replacements (x2), that gets expensive quick.

So....going forward, if your batteries read 12v or less, turn everything off (i.e. Main Disconnect off = red LED in the switch is off).

[Paprika]

Something to keep in mind: if your batteries were really brought down to 8.11 volts, as you posted earlier, they may be permanently damaged. If so, and if the problem was with the recent installation (as seems probable), then your installer should be required to pay for replacement batteries.

[Land Sailer]

I was quite worried at all the battery readings. I started the engine and brought voltage levels up before testing my new wonderful solar charger system only to have a catastrophic failure that took my house batteries down to 8 plus Didn't cry but felt like it That's when the RV went back to the tech who I installed the controller He told me that his installation was checked and was good but that one of the panels that were installed by Airstream was hooked up wrong thus drawing power from the batteries instead of charging them. I honestly don't know enough to know what is and is not possible and who is responsible for being party to battery damage. I do know that I've never seen batteries drain as fast after being in complete sun. Solar charge in reverse.
That's why I'm wondering what the probable cause could be of this kind of drain. Obviously a wiring mess up. But wiring if what?

[uncle_bob]

Hi

Don't go to crazy on yourself about batteries. This is all based on averages. AGM's are quite rugged. They can take a lot of abuse and still keep going. Will *one* discharge ruin them? Roll a handful of dice and every so often they all will come up sixes ....

The thing you *don't* want to do is run below 12V on a regular basis. That's like rolling the dice again and again and again. Watch what's going on and get on some sort of charger if you are approaching 12V.

The significant units for battery life are not years. The more important units are charge / discharge cycles. Depth of discharge matters a lot in terms of how many cycles you get. It could be 150 at one level and 900 at another level. If you full time and do a deep cycle every couple days, you will replace well made batteries once a year. If you pretty much never cycle the batteries, they might last a long time ( yes, years do eventually matter ).

If constantly watching stuff is taking the fun out of all this, there are ways to automate the process. A variety of outfits will sell you gear to do it. A Victron Battery Protect is one of many that will cut off the battery when it gets low. You ... errr ... don't put one on the starting battery ...

Bob

[Boxster1971]

Good advice from uncle_bob. The Lifeline AGM batteries in Interstates are rugged an can be run down, but have to be FULLY recharged within a day or so. That men’s over 24 hours plugged into external power to get recharged properly by the Magnum unit. Solar or driving alone will not do it.

[uncle_bob]

Hi

Worth repeating in terms of *all* battery charging. You can't use voltage as the way to tell if the batteries are fully charged. It just does not work. It takes a lot of time to shove power back into a lead acid battery. If the voltage suggests it's "full" run it for another 8 to 10 hours to be sure, even on a normal charge. (or accept that they aren't fully charged).

This problem gets a lot of people. "My batteries die to fast". They watched a voltage while charging and shut things down when it hit that voltage. Rather than being 100% charged they are at 80%. Since you only go down to 50%, that's close to a 2:1 difference in how long they will run.

One thing you very much do *not* want to do is perpetually under-charge your batteries. If you fall into a pattern ( say with a generator ) that does this, a variety of bad things can happen. Even if they don't get flattened, a full charge is needed on a regular basis.

If you go over to lithium's they have their own wants and needs. The "long charge" is one thing you don't need with them. In return you get to worry about cold temperatures ....

Bob

[Paprika]

"You can't use voltage as the way to tell if the batteries are fully charged."

Very true. That's why a battery monitor is essential for anybody who's not planning to be plugged in most of the time. For flooded lead-acid or AGM batteries, you can't beat Balmar's Smartgauge. Less expensive alternatives are Victron's BMV-712 (with Bluetooth) or BMV-702 (without) - and the latter two are appropriate for lithium batteries. But to repeat Bob's point, any of the above is way better than trying to guess battery state based on voltage.

[Boxster1971]

+1 on NOT using voltage as measure of battery charge. Sometimes I wonder if most RV manufacuters are getting kick-back from battery companies by installing voltage devices to measure battery charge. They are a sure way to quickly destroy your batteries.

The only accurate way to measure battery charge state is meter system with a shunt that records current going in and out of battery. There are many good options available. John mentioned a few. I installed a BlueSky Pro Solar control panel when I did my solar upgrade, that includes a shunt meter to measure current in and out of batteries.

I also added a Magnum BMK battery monitor when installing a MS2000 Inverter/Charger.

A good medium priced charge meter is the one made by Bogart Engineering. The Trimetric are highly rated by many sources.

http://www.bogartengineering.com/pro...rimetrics.html

https://www.solar-electric.com/bogar...y-monitor.html

[AirstreamInc]

Hi Dena_m,

Please send us a direct message with your contact information and the last 6 digits of your VIN so we can share it with our Customer Service and Technical Support team.

Thank you.

[Land Sailer]

I waited for the busy summer season to be over before I left on a road trip. Just got back from a week in the mountains, 4 days without electrical hookups. The mppt controller with 300 watts of panels and 4 house batteries seemed to do the trick even with filtered light until 1:00. All I ran was the frig.

I do have a "how to use" question, however. I noticed that both main and auxiliary batteries were reading very close to the same the entire time. Is this normal? When does the isolator kick I. To prevent the chassis battery from being depleted? Hoping my system is installed correctly.
Also, how much should I expect the batteries to loose overnight with frig only being used.... other small system draws, of course, too.

[uncle_bob]

Originally Posted by Dena m

I waited for the busy summer season to be over before I left on a road trip. Just got back from a week in the mountains, 4 days without electrical hookups. The mppt controller with 300 watts of panels and 4 house batteries seemed to do the trick even with filtered light until 1:00. All I ran was the frig.

I do have a "how to use" question, however. I noticed that both main and auxiliary batteries were reading very close to the same the entire time. Is this normal? When does the isolator kick I. To prevent the chassis battery from being depleted? Hoping my system is installed correctly.
Also, how much should I expect the batteries to loose overnight with frig only being used.... other small system draws, of course, too.

Hi

A lot depends on what the voltages were when the same. While charging, indeed, the voltages on both sets will be the same. They should "depart" when the solar is not charging things and after the various loads have pulled down the house battery set. With really big house batteries, they may not pull down very fast ...

Bob

[Land Sailer]

I had the BMV 712 installed as well. Think I'll have to monitor it more often to have a better sense of what is going on.
Any thought on the drain of the Magnum? ... installing an on/off switch?

Any idea as how low the chassis battery should be allowed to go? I'm still a bit insecure as to whether or not the intire installation was done properly so that everything will work to capacity.

[uncle_bob]

Originally Posted by Dena m

I had the BMV 712 installed as well. Think I'll have to monitor it more often to have a better sense of what is going on.
Any thought on the drain of the Magnum? ... installing an on/off switch?

Any idea as how low the chassis battery should be allowed to go? I'm still a bit insecure as to whether or not the intire installation was done properly so that everything will work to capacity.

Hi

It is not uncommon for an inverter to pull a half amp just sitting there turned off. If it's turned on and running nothing, a couple amps is still in the "that happens" sort of range.

On any lead acid battery, getting below 12.0V at 70F is not a really good idea. If that's happening, it is reason for concern. They should typically idle at about 12.7V when you are no longer charging them. It will take "a while" (like an hour or more) for them to drop from the typical 13.6V charge level to 12.7V. That process is normal and it's just the way the batteries work.

The only "real" voltage is what you read on the battery posts with a multimeter. If the BMV 712 is hooked up right, that's what it will show. Most voltage readout panels in RV's are hooked in away from the battery posts. That makes them report the wrong numbers under various conditions.

No matter where you are reading the voltages, they do "settle" after the battery has been charged or discharged. Trying to get voltage numbers under load or quickly after charging is not going to be very accurate.

By far the best way to go is to make sure the BMV712 is properly installed and set up. Use it to tell you where you are on the house battery. For the chassis battery, it's not going to be reading voltage the chassis battery posts ... take it as a guess in that case ....

Bob

[Boxster1971]

Originally Posted by Dena m

....



I do have a "how to use" question, however. I noticed that both main and auxiliary batteries were reading very close to the same the entire time. Is this normal? When does the isolator kick I. To prevent the chassis battery from being depleted? Hoping my system is installed correctly.

Also, how much should I expect the batteries to loose overnight with frig only being used.... other small system draws, of course, too.

When you have a charging source on the coach/house batteries, such as solar it’s normal for the two battery systems to be connected so the chassis battery stays topped up.