Cells in case or not in RV Compartment?

[Dem66]

I am a newby and apologize if this has been discussed a lot but I have been searching for some time and can't find the answer. I have order 8 Lifepo4 3.2 volt 280AH cells from a link on @Will Prowse resource page:

520.0US $ 35% OFF|NEW 3.2v280ah lifepo4 rechargeable battery lithium iron phosphate solar cell 12v 24v no 280ah eu tax free usa fast ship|Rechargeable Batteries| - AliExpress

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This will be a battery replacement for a 1991 Camper Trailer we have been remodeling. It will be a basic Boondocking system with no solar or inverter but we may want to upgrade in the future. I am sure I will have more questions but the first question I need answered (because it will be the basis for my design) is:

This is going in a compartment in the RV built specifically for the batteries and it will be a tight fit with the cells but not too tight. Do I need a case for the cells?

I understand I need to compress the cells and have an idea for that but this will fit a lot better if I dont need to encase them.

Thanks in advance.

Dan

 

[MisterSandals]

Do I need a case for the cells?

No but if your battery compartment is open to the elements you may need to evaluate your exposure to things like moisture and temperature.

 

[Dem66]

Thanks for the reply. They will be sealed from the environment but your point you bring up about temperature leads me into my next question. What do I need to do if anything with these cells for winter storage? We live in the mountains of Colorado and in a typical winter we will hit -40 degrees Fahrenheit at least once. Do I need to pull them out of the RV for winter storage and store them in a heated space? Again this will affect my design.

What about heat in the summer when in use and when just parked in the yard? We rarely get out of the 70s in the summer.

This compartment is accessed from the outside of the RV by a locked and weather sealed door but not environmentally controlled ie. Heat or air-conditioning.

Thanks,
Dan

 

[Sojourner1]

560ah @ 12v is alot of power for a no inverter system seems almost wasteful to power only 12v items. For a basic boondocking system also seems like a waste not to add solar unless you like the sound of a generator.

Assuming your compartment is inside the trailer and out of the weather you don't need a "case" but need to protect them from movement and something coming in contact with the cell connections.

 

[Dem66]

I get what your saying about the amount of power but won't this allow us to go longer without running the generator? Also I am looking to the future of adding at least an inverter if not solar also. Just my thought process maybe it wasn't a good one. Lol
Dan

 

[Cdkipp]

Yes you dont need a formal case but you need to stop the movement or the terminals will get damaged at the busbar connection. I frame them in with 2x2 around the bottom or aluminum angle. I have them setting on a separate board and that board is screwed down so they cannot bounce.

 

[Sojourner1]

I get what your saying about the amount of power but won't this allow us to go longer without running the generator? Also I am looking to the future of adding at least an inverter if not solar also. Just my thought process maybe it wasn't a good one. Lol
Dan

Sure it will but only having lights and other misc draw items is peanuts. What are you going to use to charge the bank? If your staring from scratch with your rebuild now is the best time to add a couple panels and small inverter and possibly not need the generator except in shoulder seasons.

 

[Dem66]

Yes you dont need a formal case but you need to stop the movement or the terminals will get damaged at the busbar connection. I frame them in with 2x2 around the bottom or aluminum angle. I have them setting on a separate board and that board is screwed down so they cannot bounce.

Dhasper that is similar to what I'm thinking I just need to figure out if I need to be taking them in and out for storage.

 

[David S]

Alternately, if you are just planning to run 12v loads for a weekend and you plan to charge from shore power before you travel, there’s nothing wrong with the approach as a starting point. You could certainly run those 12v appliances for quite a while on 6kWhr of LiFePO4. That said, you will need a different converter to charge from shore power and that will be likely be duplicative of a later inverter charger purchase. You also need to consider that most common wisdom suggest that you must compress these Eve style cells so that the don’t bloat if there’s a charging issue and that you cant charge them below 32F.

 

[Dem66]

Sure it will but only having lights and other misc draw items is peanuts. What are you going to use to charge the bank? If your staring from scratch with your rebuild now is the best time to add a couple panels and small inverter and possibly not need the generator except in shoulder seasons.

We started this project in April of 2020 and were using it as we were remodeling it last summer. So we already have the generator and built a slide for it in one of our storage compartments. They trailer currently has a cheap lead acid battery that died at the end of the season prompting this upgrade. An inverter is definitely in the plan but like you say maybe we should consider that now. I am new to RVs so I would have to figure power requirements and what we can run.

I am at work now but tonight I will post all the equipment I have purchased so far for this battery upgrade and get your guys opinions.

Thanks a lot for the help.

Dan

 

[Dem66]

Here is the equipment list I have already purchased but I have not received everything yet:

The above mentioned 8 each 3.2 volt 280AH Lifepo4 battery cells.

After research here I wanted to buy a Overkill or JBD BMS but they were out of stock so I ordered This BMS from Amazon:

Amazon.com: Smart BMS 4S 12V 120A Lifepo4 Lithium Battery Management PCB Protection Board with Balance Leads and Wireless Bluetooth Module - Supports 4 Cells 12.8 Volts DIY Programmable: Electronics

Buy Smart BMS 4S 12V 120A Lifepo4 Lithium Battery Management PCB Protection Board with Balance Leads and Wireless Bluetooth Module - Supports 4 Cells 12.8 Volts DIY Programmable: 12V - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

I ordered this to replace my 40 amp converter/charger to a lithium compatible model:

https://www.amazon.com/gp/product/B07DP3J3FD/ref=ppx_yo_dt_b_asin_image_o02_s01?ie=UTF8&psc=1

Victron BMV-712 Smart battery monitor with temperature sensor.

I ordered this to balance the cells:

Amazon.com

 

[rickst29]

If your RV compartment has been sealed from the outside (and compartments built for lead-acid batteries ALWAYS have vents); then avoiding a fully-enclosed case might have some advantages:

1. Saves Cost, and Saves weight;
2. Provides better airflow for cooling a BMS (as well as battery cells);
3. Allow for heating-pad trickery WITHOUT the case "slowing up" the heating pads from contacting the actual cells.

Although I have two "plastic box" pre-built batteries in a sealed battery compartment already, my new DIY battery will not be fully enclosed. In my RV, the compartment itself provides substantial insulation (and its inside wall allows for a thermostat-controlled fan to assist in cooling things down, under bad circumstances). Dust entry is nonexistent, except for the fan exhaust slot and corresponding free air intake.

But most importantly - I feel that a fully constructed battery is largely immune to small amounts of dust. The bus bars and BMS connectors are all clamped tight, and nothing much happens with a thin layer of dust over on the battery cells. When it builds up to a point it could maybe create short circuits - I'd have hit it with the "blower" attachment of a vacuum cleaner long before then, just I as I do with my "desktop" computer case sitting on the floor at home.

 

[Dem66]

Thanks everyone for the comments. So based on the comments it sounds like I don't need a case but now I need to determine if I need to remove the batteries for winter storage.

From some farther research I did it sounds like I should not have to remove them but I got conflicting information. A Battleborn video says to charge up the batteries first and then disconnect them for winter storage. Another source said to only charge them up to 60 to 70 percent and then disconnect them. What is the consensus on what to charge them to before disconnecting them?

The other item I purchased that I didn't mention earlier is a negative battery cut off switch. I originally planned to wire the BMS so the power was cut to it when the disconnect switch is off is this a bad idea? Should I wire so the BMS stays on when the switch is off?