Parallel Batteries Solar charge

[The Happy Beast]

Ok, here is my dilemma. I have a 30' Jay flight SLX, it came pre wired for solar. It came with one 12V Interstate deep cycle battery. I added an additional identical Interstate battery. The two were attached in parallel. Then I added 2-100 watt Renogy solar panels and the voltage regulator. My issue is that the batteries show they are charging, but after a 24 hour period, the batteries are dead. Looked at You tube videos, the batts are connected correctly. Very frustrating, any solutions??

[Spower]

Something is running and draining them.

[ARoamer]

Any idea of how many amps from solar controller are going to your batteries? How much power is being used by your RV? Low sun angle in winter gives me about half of what I get in summer with my flat roof mounted panels.

[The Happy Beast]

Originally Posted by ARoamer

Any idea of how many amps from solar controller are going to your batteries? How much power is being used by your RV? Low sun angle in winter gives me about half of what I get in summer with my flat roof mounted panels.

6.7 Amps to the batteries

[The Happy Beast]

The only things that are in the background are the CO2 monitor and the clock on the radio, unless I'm unaware of other factors draining the batteries.

[ARoamer]

For 200 watts of solar it actually sounds about right as far as your solar output amps for this time of year. As I stated I am seeing about half of what I usually see in the summer with my flat mounted panels. If you can face them into the sun you will have much higher output. With shorter daylight hours and low sun angle you're probably not getting enough charge to offset your rv's power useage. Before solar my power hungy Pinnacle would drain the original 12v deep cycle in 4 days when sitting unplugged and idle.

[ARoamer]

Originally Posted by The Happy Beast

6.7 Amps to the batteries

6.7 amps x 12= 80.4 watts

I'm currently seeing 22 amps in sunny AZ with 640 watts of solar flat on roof.
22 amps x 12= 264 watts.
Both examples are similar in that we are getting less than half of rated output. Add shorter daylight hours and it may not be enough to get you fully charged depending on your RV's power needs. Look at your RV's amp draw.

[The Happy Beast]

The curious thing is that when I have both batteries hooked up to the solar, the batteries go dead. When I take off one of the batteries, it charges fine, and seems to hold the charge.

[ARoamer]

I'd check your batteries, they should have similar voltages after sitting disconnected. Also, do a load test, some auto parts stores may do this for free, Generally batteries should be matched with the same model and ideally the same age. It is possible one battery could have an internal short.

[bluztoo]

Have you pored over the charge controller instructions. Might be set on the wrong battery type. Or some other setting. Strange that it only acts up when the two are in parallel. Although if one of the batteries is bad that would take it down. But as already said, likely some draw going on somewhere. I’m using a Renogy portable kit - 200w suitcase. Getting as high as 12.9 amps mid-day in southwest Arizona. I had to finally read the instructions myself. My wife says men only read manuals as a last resort!

[ARoamer]

""My wife says men only read manuals as a last resort!""

True, It’s the old, “men never ask for directions” bit!
Usually my manuals never get looked at unless A. It's an expensive thing that I don't want to pay for twice if I screw it up, or B, My eyes glaze over in confusion while trying to figure it out. (Example- I discovered my iRV sound system was wired wrong from the factory, no sound. Did the manual help? Nope!)

Found this online-
"Research shows that men are usually more confident in their ability to fix things, so why bother reading an instruction manual? Women, more likely to look for help, have no problem consulting an instruction manual."

[Vaquero]

The antenna booster might also be on.
Is the refrigerator turned off?

[EJH]

The oddity is the batteries are draining when both are in parallel, and connected to the trailer. That sounds to me like one battery is bad, and draining the other down.

When only one is connected to the trailer, how long does it last (check the voltage every few hours, or couple times a day, etc). Try each battery alone connected to the trailer. Does one die quicker than the other?

Also, try putting a clamp meter (amp meter) around the battery connection. If you do this at night, or without the solar charge controller connected, you will get an idea of the parasitic current draw. This value can be all over the place, but likely with just the CO2, clock, etc should be less than an amp, but YMMV.


As above, any chance you have a 12V fridge that is on?

[Gusto_man]

I'm not an electrical wiz kid or anything close! I had a similar problem with my 100 watt solar panel and single battery. Even with the battery disconnect employed, I was losing charge and sometimes dead. I bought a battery disconnect mechanism for each battery post which allows me to totally disconnect from any electrical draw from the trailer, which allows my battery to stay charged and ready to go... it works for me!

[videoarizona]

Agreed. A battery disconnect switch that totally disconnects batteries from trailer is important. If trailer is in storage, then this is needed.

However that doesn't seem to be your problem.

You do need to buy a clamp on amp meter so you can see current draw.
I found my fridge, gas warning units, and the remote control board for the slide/awning all use power continuously when battery is connected. About 2.6 amps.
That's with all lights off, antenna amp off, etc.. 2.6 X 24 is how many amps/day those things draw. I then added the lights, furnace, radio, etc., And now know how much I use.

So with all that said.... The question remains about your problem.
1. Have both batteries tested.
2. Do an amp draw test on RV. Turn everything off and see what the current draw is on battery. Should be very little..... Anything more than a few amps means you have something on that shouldn't be.
3. Double check your parallel connections to the batteries and to the RV. I've seen connections where the batteries were connected in parallel but the RV
power leads all went to 1 battery. Wrong! Wired this way, all the power is going through one battery.
4. Check the connections from the solar panels to the batteries. Again, the solar cables should have one connected to one battery and the other to the 2nd battery.
IE, solar positive to battery 1 positive. Solar negative to Battery 2 negative. Or vice versa.
If your batteries are wired together properly for parallel operation, then both the solar output cables and the RV power cables should be connected to the same battery posts.
This way both the charge current and the RV draw current is going through both batteries together.

Another way to look at the connections... Is the solar and house cables should look like they are connected to one big battery. The big battery is your two batteries connected together.

Hmmm... I hope this is clear.... If not. I'm sure some one will jump in and help.
Good luck... Let us know what you find.

Forgot something.... Check to make sure your solar controller is operating. Most controllers require you to connect them to batteries first, then to the solar panels. I do believe you have this correct as you charge properly with one battery. But again. Double check!

David

[Markomyt1]

I knew a couple that purchased a tent from Walmart on their way to the campground.
He was an Engineer and was pouring over the manual, and to his dismay, the girlfriend was a marketing type and had it assembled in no time. I pointed out how they were polar opposites, but made it work. They did end up getting married... Hi Stephanie and Kevin!
It was hilarious!

[MtnGoat]

A thought. At night time solar panels will draw current from the batteries. The solar controller has diodes to stop this draw. Not saying this is the problem. Just saying if the controller is malfunctioning, the results can be dead batteries.

[rhermsen]

There are some red flags in your details... Different aged batteries mean your charge will be off...you will only get what the worst battery can do... You also say both batteries are connected to the solar panels... Are you connecting the solar to the batteries as a single unit like the rig is connected to them?

Lead acid batteries are crap unfortunately. Their weight to power to cost ratios are poop.

Are you using an mppt or pwm controller?

My lead acid battery only lasted a few days with the radio clock and Co detector. It is also possible your solar is a bad setup and if there is no shiny that it is draining the batteries in the darkness.

[TomC_AZ]

As others have mentioned if the batteries are not of the same age that could cause an issue.

But I am wondering about the connection to the batteries. How are they connected?

They should be connected such that one battery has the positive to the trailer to it and the other has the negative. This helps to ensure that both batteries are "participating" equally with the electrical system. If those connections are only going to one of the batteries then that could cause this issue.

Also check simple things first, do both have water or are they dry?

[The Happy Beast]

Thank you so much for the shared expertise on this issue. I had the battery tested, the shop said it was ok. The problem persisted. I had to take the trailer in for warranty work. They tested the battery, and lo and behold it was bad! So I quit pulling out what little hair I have left. The battery was replaced with new, and the solar charging is doing what it is supposed to do.

Thanks to everyone on the forum for sharing.