Home Forums Hunting & Shooting Hunter's Campfire Solar Panel RV Question?

Had a newly installed and expensive lithium battery go tits up in our travel trailer. Manufacturer shipped us a new one (12V - 200 amp hr) at no cost).

In an effort to detect potential cause/effect for battery failure on our end, I did voltage checks at my battery terminals with every conceivable combination of electrical input with and without the battery installed.

Step one was linking my three 100-watt solar panels and checking their pooled voltage at the common plug. Reads a constant 19.4 volts.

Next, that plug is connected to the trailer with no battery installed. Voltage measured at the battery cables pulsed between 13 and 16 volts at about 1/2 second intervals with the power passing through the trailer's onboard solar controller. Similarly, an LED dome light inside the trailer also cycled on/off at the same frequency.

Pulsing vanished with the panels plugged in and the battery connected with 13.32 Volts at terminals.

Shore power with battery installed and no panels also reads 13.32 Volts at battery terminals.

Shore power plus solar panels with battery installed reads 13.48 Volts at terminals.

My question: Is this pulsing from my solar panels typical, or do I have a solar panel controller issue?

Living in a 1-horse town here with no local expertise for a face-to-face discussion. Informed input is greatly appreciated.

Read the manual on your controller. The default is usually for a lead acid or AGM battery which needs to charge at that 13.5v. There should be a way to set it for lithiums with a 14.4 to 14.6 v setting. We installed a lithium battery and I had to reset my controller for it. Recharging at 13.5 will reduce the life of your battery as it'll never get a full charge.

Charge controllers pulse on and off to control the total amount of average current delivered. Half second cycles seem very long to me.

As mentioned, lead acid, Li-ion, and LiFePO4 batteries all have different preferred charging schemes. Make sure your charge controller is set up for the one you have.

If you give me some specific info on what system you have and what RV manufacturer it is, I can give you a better answer. The short of it is, it most likely is normal as was stated above. We do get pulse readings when dealing with solar controllers. Also, as was stated, make sure your controller is set up for lithium. If its not, it wont cause the battery failure. It just wont charge at the higher rate that lithium needs to fully and properly charge. Shoot me a pm if you want. I've been in the RV industry for 25 years

One of my customers installed a high dollar lithium battery in his toy hauler last week and he told me that he had to put a disconnect switch on his solar panels so he wouldn’t damage his new battery…. It’s my understanding that certain types of lithium batteries are meant for a fast charge and the trickle charge of solar will fugg em up…
It’s what I heard, not what I know.

If I disconnect my battery's from my controller it reverts back to factory settings every time.

I have to completely reprogram the controller.

My controller warns of that in the setup instructions, of course I had to try it and sure enough...

The Lithium Battery's that I purchased have a Mother Board in them that monitors the battery's Charge , Discharge and Temperatures to protect them from over Draining , Over Charging and Charging at the proper temps.

I have a mid level Charge Controller that freaked out when i hooked up the Lithium's to it.
The Charge Controller did not know what was hooked up to it.

I hooked up the Cheap harbor Freight special Charge Controller to a single Lithium battery and it took several weeks for the lithium to figure out what was charging it and it still has hiccups 2 years later at times.

Lithium Battery's are great battery's but it takes a bit of experimenting to get everything working right.
And the new high end Charge Controllers are so dam complicated it took altE 2 hours to help me program my Magnum Charge Controller and the guy helping me had me set the Battery type to Other because there was no setting for Lithium.

You can purchase Lithium battery's with out the Mother Board in them but then you need to purchase one for your system (I forgot the name of the Board)

Troops:

Appreciate the comments. Took a look at my controller and there's no make/model or any information as to its source. Googled the 18-19 character codes on its labels and nothing was found.

I did locate a small 1 1/2" by 3" paper manual among the rig's paperwork and am confident it was authored by an illiterate Asian. No indications there either as to make/model etc. As an example of the text therein: "(Note: when choosing LED shows decimal mode, the decimal point will be will be always bright, it doesn't affect the controller functions, only for differentiation.) That's quite helpful (Not).

Saw nothing about Lithium in the manual either, so to be on the safe side I'll order up something that at least suggests it's Lithium compatible and arrives with an English installation/programming guide.

I for sure do not want to fry another battery. Given their cost, I don't think the company will be as friendly on a second go around.

Just a warning: If one is starting out with a lead/acid system, switching to Lithium is not simply a plug and play deal.

Thanks for trying,

Zamp solar is in Bend, they make a really simple charge controller that works great. Maybe give them a shout, I have been very pleased with their products.

Backroads:

Might just give them a call. Thanks.

1 minute,

I chased electrical problems in mine for a while too. It was a combo controller for the solar panels, generator, and shore power feeding into two AGM batteries for the coach, and also into two AGM starting batteries for the engine. I finally found a bad grounding strap, and no more problems.

Good Luck.

You bet, good luck getting your rig sorted.

Take a look at Xantrex.

Did you switch out the AGM for lithium???

1 minute, try calling the supplier of your battery and see what they have to say…

MM,

I stayed with the AGM. I sold it several years later, and it was still working great with the new ground strap.

Very true. Li's need a higher charging rate than what many RV's provide with the built-in charger. Ours charged at 13.8 when 14.5 is needed. I bought a simple charger made for Li's and simply wired it in next to the old one that I disconnected. All the juice still goes through the fuses and circuits, just at a little higher voltage. It all works fine. Some year if I decide to return to wet or AGM's, it'll be easy to swap it back to the old charger. I assume the higher end RV's have some kind of switch to throw to use Li's.

Li's can't be charged below freezing. It will permanently damage the battery. The better one's with the BMS won't let it charge that cold. If you have lots of cash, you can get Li's with heaters to warm up the battery so you can charge it in the cold. The one's I looked at add about 50% to the price.

Troops:

After half a day of research I am going to purchase a:

Renogy
Rover Li 30 Amp MPPT Solar Charge Controller
RNG-CTRL-RVR30-BT-US

With the blue tooth link. That way Cookie will be responsible, as I only use my phone to call people.

Thanks again for the suggestions.

Renogy makes a good controller. You don't need to charge the battery to 14.6. That will actually probably reduce the life of a LiFePO4 battery. Max charge per cell is 3.65. 4 cells at 3.65 is 14.6 but the discharge curve of LiFePO4 cells is such that you'll get the same capacity out of a battery charged to between 13.8 and 14.2. (3.45 to 3.55 per cell). I'd set the controller to charge to about 14.0 boost and 13.2 float and you should be good for a long life and still full capacity of the battery.

The BMS (Battery Management System) (which is internal to the battery) will control the charge/discharge limits. A decent BMS will also handle the high and low temp rates as well.

For diagnostics and maxing the use of your battery bank, get one of these
https://www.amazon.com/Victron-Smar...&hvtargid=pla-905632901260&psc=1

or the next level up that actually has an LED display panel. You can learn alot about charging and discharging your batteries, maximize the use of them, determine big drawdown items, know when the batteries are fully charged, etc.

On my new Montana I put in 400A of Lithiums, trailer already had this device which is nice if you like bluetooth, lol. Cookie can monitor them for you.

One major issue I learned was the LI ready 55A charge system of the main panel was only getting the batteries about 40 A, and the Victron helped a lot during my trying to see how my 2200I generator recharges them for dry camping. Turns out I had to swap the #4 wire to a 1/0 wire from the charger to the batteries to get the full ( 53a) recharging ability of the charger, vs buying a stand alone unit placed closer to the battery bank to get maximum recharge rate , although my bank could be recharged at 200A (50%) which isn't realistic for my generator to support.

My rig has a 300W single panel using a 30A MPPT Victron charger, but I haven't been out to see how well that helps keep the batteries charged

Good luck, the Lithiums should be nicer than AGM or wet cells for deeper discharge and faster recharging ability.