LFP batteries but not dry camping

[chriscowles]

We have 200Ah of LFP batteries with 720W of solar panels, a 40A Epever solar charge controller, and a non-Li compatible WFCO 8955 converter/charger. We find ourselves camping with shore power far more often than without.

Does that pose any risk to the long-term health of the batteries? Since the converter doesn't exceed 13.6V, can I just leave the solar panels off until needed so the LFP batteries don't live at 100%?

I appreciate any wisdom you can share.

[18LT]

Yes, you can use the converter to stay around 13.6 volts. I worked that same problem in reverse though.
I have the converter switched off and use my solar panels (two 190-watt panels) and mppt controller, which is set for 13.6 volts bulk and 13.2 volts float. We have a bit more reserve energy than you, 500 amp-hours at full charge, so the chance of us dipping into the bottom 25-30% is probably less than you might run into. You have almost double the solar capacity though.
I'm only familiar with my controller so I'm not sure if you can set the voltage values on yours.
Another option, which I used last year, is to buy a 0-30 volt, 0-10 amp constant current/constant voltage power supply to charge and maintain the batteries. It cost 44 bucks on Amazon. I set it for 13.2 volts and 10 amps and it worked flawlessly. At that time we had two 100ah batteries.
I'm certainly no expert on lifepo4 batteries so I'm reluctant to give advice on whether or not a constant 80% charge will shorten their lifespan.
My batteries will probably outlive me.

[darrellr]

Originally Posted by chriscowles

We have 200Ah of LFP batteries with 720W of solar panels, a 40A Epever solar charge controller, and a non-Li compatible WFCO 8955 converter/charger. We find ourselves camping with shore power far more often than without.

Does that pose any risk to the long-term health of the batteries? Since the converter doesn't exceed 13.6V, can I just leave the solar panels off until needed so the LFP batteries don't live at 100%?

I appreciate any wisdom you can share.

Having some of the same concerns, I recently purchased the WF-9865-AD to replace the charger that came in my Riverstone. It autodetects LFP cells. Should be a pretty easy replacement. They also make a WF-9855-AD for yours. 2 wires, a ground, and a 110v outlet, direct replacement. I paid $300 for mine, yours might be a little less. Will keep the original just in case of failure on the road.

[chriscowles]

Originally Posted by darrellr

Having some of the same concerns, I recently purchased the WF-9865-AD to replace the charger that came in my Riverstone. It autodetects LFP cells. Should be a pretty easy replacement. They also make a WF-9855-AD for yours. 2 wires, a ground, and a 110v outlet, direct replacement. I paid $300 for mine, yours might be a little less. Will keep the original just in case of failure on the road.

My issue is not that the WFCO can't charge the batteries fully, because the solar panels can top them off when needed. My concern is the effect of the batteries staying at or near 100% SOC because we're often on shore power.

[TacomaJoe]

I do the same as 18LT. I have the 8955 converter, 300W solar on a 280Ah battery. I turn off all charging at times to cycle the battery down.

I have another 75A charger that I throw on a generator when I in the boonies with no sun.

My battery has a bluetooth BMS and I have a shunt meter to keep track of battery level.

[TitanMike]

Originally Posted by chriscowles

My issue is not that the WFCO can't charge the batteries fully, because the solar panels can top them off when needed. My concern is the effect of the batteries staying at or near 100% SOC because we're often on shore power.

If on shore power for extended periods of time why not switch off solar panels and also switch batteries off.

Converters are capable of powering all 12v devices when those items one need an inverter for are now getting 120v power direct. Don't even need a battery while on shore power.

Once charged and disconnected a LiFePo4 battery can sit for months with no need for even a maintenance charge.

[mlmay12]

Originally Posted by chriscowles

My issue is not that the WFCO can't charge the batteries fully, because the solar panels can top them off when needed. My concern is the effect of the batteries staying at or near 100% SOC because we're often on shore power.

Turn off your Converter Circuit Breaker when not needed. I keep mine off until I need to charge the Batteries.

[jimmoore13]

I think this is your answer.
https://www.solacity.com/how-to-keep...tteries-happy/

This professes to be the key to "set it and forget it."

[nvs4602]

13.6v is a good float voltage for lifepo4 batteries. It keeps the cells at around 3.4v which is a good resting voltage.

[chriscowles]

Originally Posted by nvs4602

13.6v is a good float voltage for lifepo4 batteries. It keeps the cells at around 3.4v which is a good resting voltage.

So, draining below that point and leaving the solar panels off should result in recharge to and maintenance at a healthy level when the converter is on?

Perhaps I can claim I didn't replace the converter because I'm smart, rather than because I was cheap.

[chriscowles]

Originally Posted by mlmay12

Turn off your Converter Circuit Breaker when not needed. I keep mine off until I need to charge the Batteries.

I'm most concerned with not maintaining them at a level that's too high for long-term health. Is it important to allow it to actually cycle up and down?

[chriscowles]

Originally Posted by TitanMike

If on shore power for extended periods of time why not switch off solar panels and also switch batteries off.

Converters are capable of powering all 12v devices when those items one need an inverter for are now getting 120v power direct. Don't even need a battery while on shore power.

Once charged and disconnected a LiFePo4 battery can sit for months with no need for even a maintenance charge.

We're both dependent on CPAP. Our sleep has been disturbed by power failures in the campground. By leaving the batteries on and using a 12V power cord for the CPAPs, we avoid that.

With respect to the batteries sitting for months, does it affect the lifespan to be at 100% for prolonged periods?

[01tundra]

Originally Posted by chriscowles

I'm most concerned with not maintaining them at a level that's too high for long-term health. Is it important to allow it to actually cycle up and down?

I used to try to keep my Battle Born batteries resting around 90% SOC, but Battle Born told me to just charge them to 100% and don't worry about it. They said it will not hurt anything keeping them stored at 100%.

My Progressive PD9160ALV bulk charges at 14.6V and floats at 13.6V. I keep the batteries at 100% SOC and leave them turned off while at home on shore power. I turn them on during transit to power the emergency brake controller, then turn them back off once we get to a campsite if we have shore power at our site. The convertor takes care of any 12V needs while we're on shore power.

I'm much happier keeping them at 100% SOC because the few times we have lost shore power at campgrounds in the past we were starting at 80%.

[darrellr]

I leave my batteries on at all times. I trust the solar controller and the charger will properly maintain the batteries for me. I also leave the inverter on when plugged in to help cover any unplanned power outages in the campground. l am sure the residential fridge will be fine until we get back from whatever we are doing, but it is a little more piece of mind to leave it all hooked up as designed.

[01tundra]

Battle Born did also state that they have worked extensively with Progressive and that I could just leave the batteries connected all of the time and allow them to float, but they also said that what I am currently doing is perfectly acceptable as well.

[TitanMike]

Originally Posted by 01tundra

I used to try to keep my Battle Born batteries resting around 90% SOC, but Battle Born told me to just charge them to 100% and don't worry about it. They said it will not hurt anything keeping them stored at 100%.



My Progressive PD9160ALV bulk charges at 14.6V and floats at 13.6V. I keep the batteries at 100% SOC and leave them turned off while at home on shore power. I turn them on during transit to power the emergency brake controller, then turn them back off once we get to a campsite if we have shore power at our site. The convertor takes care of any 12V needs while we're on shore power.



I'm much happier keeping them at 100% SOC because the few times we have lost shore power at campgrounds in the past we were starting at 80%.

I think many are over-thinking the issue and there's a lot of misinformation floating around the 'net (who'd have ever thought?).

The actual max voltage for a LiFePo4 cell is ~4.2volts (16.8 in 4S config). Current battery and BMS design limits max charge to 14.6 which is less than 90% of battery's max voltage. Very little actual power is stored above 3.65v (14.6 in 4S)

At this level degradation of cell chemistry is minimized and unless one camps 24/7/365 on shore power their LiFePo4 batteries might well outlast them.

Again, I think the issue is being way over-thought.

[chriscowles]

Originally Posted by TitanMike

... Again, I think the issue is being way over-thought.

Now that I have everyone's shared wisdom, I'll just leave everything on and I don't have to think about it any more.

Thanks for your assistance.

[kcmusa]

You can check out some of will prowess videos on YouTube. He does a great job of testing Lifepo4 battery’s.
One video says it best to use them in the 80-20% range but also not to worry as the battery’s will probably age out before you hit the max cycle’s life. So do what you are happy with.

[Hclarkx]

Originally Posted by chriscowles

Now that I have everyone's shared wisdom, I'll just leave everything on and I don't have to think about it any more.

Thanks for your assistance.

Chris,

While that is a sound conclusion, here's an observation. Floating the LFP at 13.6 Volts will take it to 100% SOC and hold it three. The charge time from, say, 50% SOC to 100% SOC, will be long, even days, but the battery will indeed get to 100% SOC eventually.

In a recent experiment I charged a 280 Ah LFP from 90% to 99% in seven hours with the charger set at 13.5 Volts.

More than you wanted to know, but if your WFCO 8955 has three trim pots along the top of the vertical circuit board like mine, you can adjust the rightmost one to float the LFP from down around 13 volts up to 14.2 volts (assuming yours behaves like mine). I use my old 8955 as a bench supply for working with LFP batteries, including floating one at 13.15 volts while in storage. I crank it up to 14.2V for charging and balancing and such.

I do something similar with one of my Epever MPPT controllers in the RV. I have it set to bulk to 13.2V and float at 13.2V. The actual voltage is closer to 13.13 according to the overkill BMS on the battery but that's fine as anything between about 13.1 and 13.2 Volts is a good storage voltage for an LFP battery (i.e., down around 50-60% SOC).

BB batteries use cylindrical cells while most newer designs use trapezoidal cells. I don't know if this is behind BB's recommendation to store at 100%, or they just want to make life easier on their customers at the cost of some battery life. However, academic papers have shown conclusively that the trapezoidal cells live longer if stored below 100%. Though as you surmise, we are probably talking just an extra year of life many years down the road.

[ilmor]

It is harmful to LFP batteries to keep them at 100%.