storage plus battery charging

[nsdtr3]

Hi all,
Always lots of great ideas and information for those of us with challenges. We have a 2017 Montana 3720RL. We have 2 x 150W solar panels on the roof, an onan propane generator. A magnum charger/inverter, 4 Battleborn 100amp lithium batteries in parallel along with a victron BMS and MPPT solar charge controller.

See pics.

Here's our question. The RV is in a storage structure with a roof and open sides. After the batteries are charged to 14.2 they drop down in a few weeks to where they are unable to start the generator. I plug the RV into my truck and after a few minutes the batteries are charged to 11.6 and I can start the generator and charge the batteries again. I decided to purchase a portable solar panel with enough cable to place in a spot behind the RV the sun hits and use it as a trickle charge to keep the batteries charged.

I think the batteries shut off after the voltage drops below a certain range (in the 12.0)

Thoughts? I spoke to Battleborn and they suggested disconnecting the negative cable from battery to the RV after the batteries were charged above 14.2 I did do that yesterday but it is a pain to get the wrenches on the bolt and unscrew the nut. That's why I purchased the portable solar panel from Renogy.

Thanks for reading and making suggestions,
John

[jimcol]

I'd forget the solar panel just for a trickle charger and install a battery disconnect switch on the negative terminal or where the negative cable is ground to the frame. Something like this would work.
https://www.amazon.com/Battery-Disco...2s9dHJ1ZQ&th=1

[Daryles]

Even though you turn "OFF" the "BATTERY DISCONNECT" switch, there are parasitic drains on the battery. This is why it drains. Lithium batteries have almost zero internal drain. This means once charged they will stay charged for a LONG time. I believe they recommend charging lithium batteries to 80% for storage.
I put a cut off switch on the positive cable coming out of the battery box before it reaches the first red self resetting circuit breaker mounted on the wall.

[Foldbak]

If it were me I'd charge them and shut off the disconnect. I highly doubt there is enough parasitic draw to effect them. If so just remove the negative cable.

[AZ Traveler]

John,

Recommend installing a true battery disconnect switch vice taking a cable off the battery bank.

[BB_TX]

Disconnect switch at the battery is definitely the easier way and provides a full disconnect.

[nsdtr3]

can you send a pic of your setup...thanks...

[Carl n Susan]

Here is my disconnect setup. I choose to put the switch on the Ground Cable. You can see the ground cable from battery to the Shunt (to measure usage) and the buss bar. The actual ground cable, along with cables from other pieces parts, then runs to the frame from the buss bar

[Daryles]

When I installed my solar package I rearranged the wiring, installed a battery shunt, Bus bars, separated the hydraulic system on its own 80A circuit breaker and installed a 4 way switch (off, 1, 2, both). I kept the original FLA battery as a back up.

[bcrvman]

Wow, you must have spoke to either a 3rd party BB helper or it's newest untrained hire maybe a lunch room cleanup person. Those batteries should last a very long time in storage. Do NOT disconnect the cable on the battery post. You should have a disconnect like the one visible in your picture between the battery most negative and your 500A shunt. When you call or better email the BB support people and get an actual educated person, they will tell you
From the FAQ
Please watch the video above for more information on winterizing your Battle Born Batteries.

The storage temperature range is -10°F to 140°F (-23°C to 60°C). We recommend bringing the Battle Born Batteries to a 100% charge and then disconnecting them completely for storage. After six months in storage your batteries will remain 75 – 80% charged.

Storing batteries in subzero weather (-15°F or more) has the potential to crack the ABS plastic and more importantly could cause a faster loss of capacity, in some cases drastically more than the typical 2 – 4% per month loss.
end of FAQ
I see you are in OR, so the latter applies. In that case the easiest solution is to bring them indoors or add some supplemental heat. Adding a charger at those low temperatures will destroy the battery and that includes the solar. The factory installed disconnect is useless, you need to use the main battery disconnect any solar installer would have added and maybe that one visible in your picture.
Here is the FAQ
Battle Born Batteries protect themselves from charging in cold temperatures and won’t accept a charge once the internal cell temperature drops to 24°F. At this point they will continue to discharge even down to -4°F. At this temperature we recommend no longer pulling power to avoid damaging the batteries.

Insulated battery boxes, heating blankets, and placing your battery bank inside your RV will help keep the temperature stable. On the high end of temperature range, the batteries will shut down once 135°F is reached.
end of FAQ
Get some pro help, AM solar is nearby, and there are a few good/smart folks in OR, CA, WA and nearby. I am located north of you by a few hundred miles and am going on 3 years with no problems so I know what is needed.

[nsdtr3]

Thank you for the information. Have a friend coming up from California next weekend who's experienced with RV'S and motorhome battery setups. Our winter Temps typically remain above 25 degrees (usually above 32) as we get rain and not snow. Thanks again.

[bcrvman]

Originally Posted by nsdtr3

Thank you for the information. Have a friend coming up from California next weekend who's experienced with RV'S and motorhome battery setups. Our winter Temps typically remain above 25 degrees (usually above 32) as we get rain and not snow. Thanks again.

As long as he is Lithium knowledgable.
Post #8 shows the correct battery shut off solution when installed in a solar rig.