Bonehead move with batteries has me questioning capacity or battery monitor…

Having gone through a bunch of the research papers in the journals, I suspect the reason there is so much variation in recommendations is that storage SoC makes little to no difference to LiFePO4 lifespan.


Note that I'm specifically talking about storage based degradation, not degradation during cycling - those are two completely different things
 
Not that I expect it will settle the debate, but here's a figure from one of the papers showing the effects of temperature and SoC on LiFePo4 aging. There's not a huge difference, but storage at 50% SoC results in the shortest lifetime for the batteries.
 

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Having gone through a bunch of the research papers in the journals, I suspect the reason there is so much variation in recommendations is that storage SoC makes little to no difference to LiFePO4 lifespan.


Note that I'm specifically talking about storage based degradation, not degradation during cycling - those are two completely different things


Thanks for looking into this!
 
Since these batteries are recommended to be long-term stored at between 40% and 60% capacity, I turned on the inverter and plugged in a 1000 watt space heater and let it run for about 4 hours until the Victron BMV-712 battery monitor said I was at 51% capacity, so I shut down the heater and inverter, pulled the batteries out and stored the batteries in our basement.

Today I hauled the trailer to our storage facility where I soon re-learned that the electric jack will not work without the batteries installed! I mistakenly thought it would work off the tow vehicle power.

Apologies taking this thread off on another tangent, but I think this is important to mention:

Electric jack issues aside, there is another much more significant issue with towing your trailer without any batteries installed. It would have rendered the break-away brake actuation system inoperable....if the trailer had become detached from the TV!
 
So my experience with the jack... On the morning when our trailer was put into storage I pulled the batteries from the trailer for storage. The TV power was hooked up and the power jack worked fine without batteries in the trailer. After an hour's drive to the storage facility it would not. What am I missing?

We also have a Victron issue in that the monitor reads and tells us the battery voltage , but always 0% used and infinite life. So gremlins are present ... Escape have sent us a new Smart Shunt with no change.
 
Doesnt the 7 pin charge the system as you drive?
In the past, in most cases, yes. With flooded lead acid batteries or AGM definitely yes. Some folks install a DC-DC charger for lithium, which still charges from the tow vehicle but some disconnect the charging wire from the 7 pin plug.

I can see a tongue jack working while the tow vehicle engine is running. But maybe only one way, down. Depends on the output from the tow vehicle if there's too much of a heavy draw while lifting the tongue.

Ron
 
Not that I expect it will settle the debate, but here's a figure from one of the papers showing the effects of temperature and SoC on LiFePo4 aging. There's not a huge difference, but storage at 50% SoC results in the shortest lifetime for the batteries.

that article appears to be talking about Lithium ION batteries, which have a lot of differences with LFP. LFP batteries are pretty much happy no matter how you abuse them as long as you never charge them when the battery itself is below 32F, and most have a BMS that will block charging when they are cold like that.. LFP (Lithium Iron Phosphate, aka LiFePO4) are good for many 1000s of full discharge/charge cycles and at least 10 or maybe even 20 years. you can discharge them to almost but not quite 0% and they bounce right back with a full charge.
 
LFP batteries are pretty much happy no matter how you abuse them as long as you never charge them when the battery itself is below 32F, and most have a BMS that will block charging when they are cold like that..
On the subject of bonehead abuse.

I dropped 2 Renogy 100 AH LiFePO4 batteries into the trailer 2+ years ago. They were rather oddball in the sense that they have an Ethernet-type connection so both batteries could "talk" to each other. They also have a port for a switch to put the BMS into a dormant mode - presumable to lower the internal power drain to a trivial level.

But bonehead move number 1 was to leave the power switch inserted into the battery so its LED indicator was running all fall-winter-spring. When I discovered this in May - the batteries were down to 10.5 Volts. But they charged right up without complaints.

Bonehead move number 2: Although I can't confirm the temperature in the trailer, I do know that Denver, CO recorded a winter low of -19F. Renogy specified a minimum storage temperature of -20F. (Lower than any I have seen.)

And bonehead move number 3: I never upgraded any of the 3 charging systems (solar, 110, or tow vehicle) to supply more than 13.8 V (lead-acid level). Which I believe means the battery balancing system (BMS) was never triggered.

But after heaps of abuse the batteries seem good as new. :crazy:

In the meantime my Dometic fridge was mercifully replaced with a compressor fridge, and the new power requirements suggested a battery upgrade before our 15 day adventure in Big Bend in March. So in a few days I will be replacing my 200 AH with 600 AH of storage capacity. Still just a pair of batteries and still lighter than the original 200 AH of lead-acid. And the new batteries have a low temperature charge cutoff, which the Renogy's did not have. Plus this time around they will get an occasional feeding of 14.4 V from solar. They should be happy batteries.
 
They were rather oddball in the sense that they have an Ethernet-type connection so both batteries could "talk" to each other. They also have a port for a switch to put the BMS into a dormant mode - presumable to lower the internal power drain to a trivial level.

But after heaps of abuse the batteries seem good as new. :crazy:
I have one of that type. My newer Renogy battery doesn't have those ports. After a few incidents with the battery I stopped using the ports to put it in limbo. Seems fine to just use it like any other lithium battery.

Ron
 

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