More on LFP Charging

[BFL13]

Some "sales" statements here, but also some possibly good info of interest.

One thing is they found longest life (most cycles) was to charge at 14.4v but at lower amps at 0.3C.

Some LFP owners on here ISTR have taken to charging at lower voltages hoping for longer battery life. Perhaps it needs to be established which is correct--lower amps or lower voltage?

They say 14.4 vs 14.6 to reduce stress, and recommend their own charger (of course!) which is single stage 14.4--BUT they say shut charging down-disconnect- once the charger says the batt is full. (light comes on---what makes that light come on? oh well)

They are strongly against floating! see why.

Anyway, it covers some of what has come up on here lately.

https://dakotalithium.com/2021/09/22/how-to-charge-dakota-lithium-and-lifepo4-batteries/

[StirCrazy]

jaycocreek wrote:

wow, I can't imagin using that much power haha, for me I use 90ah max in the big 5th wheel in the winter running the furnace, I don't use AC when not plugged in so that might be the majority of the difference. in the camper I don't think I have used over 36AH in a night at 30degrees F.

That does seem like a lot huh...I am using between 50-75ah a day right now but I'm in a 9.6 ft truck camper...Not much room for batteries or panels compared to my old 35ft Jayco 5th wheel..As was said earlier,each person has different needs for his use and rv type...Once I finish my other controller and run my 5k window ac off of solar,my use will go way up...

With 3 inverter Generators,I have to stop buying batteries and solar somehow..:B

ya Im kind of lucky with the camper in the way that I have no AC, no microwave and no inverter. a normal day if I don't need the furnace like my trip to the island last week, I use 5 to 8 AH, and I think mu solar panels had the batteries back to 100% before I got out of bed in the morning :B

[jaycocreek]

wow, I can't imagin using that much power haha, for me I use 90ah max in the big 5th wheel in the winter running the furnace, I don't use AC when not plugged in so that might be the majority of the difference. in the camper I don't think I have used over 36AH in a night at 30degrees F.

That does seem like a lot huh...I am using between 50-75ah a day right now but I'm in a 9.6 ft truck camper...Not much room for batteries or panels compared to my old 35ft Jayco 5th wheel..As was said earlier,each person has different needs for his use and rv type...Once I finish my other controller and run my 5k window ac off of solar,my use will go way up...

With 3 inverter Generators,I have to stop buying batteries and solar somehow..:B

[3_tons]

Heck, with all that power you better be careful, they might try regulating your rig as a mobile utility supplier - lol 🙂 !!

3 tons

[StirCrazy]

Itinerant1 wrote:

I don't know now what you mean by how do I manage on less than 2304wh, 175ah +/- daily? Batteries

Yes, solar is always running loads during the day and the balance of power charging the batteries if needed.

wow, I can't imagin using that much power haha, for me I use 90ah max in the big 5th wheel in the winter running the furnace, I don't use AC when not plugged in so that might be the majority of the difference. in the camper I don't think I have used over 36AH in a night at 30degrees F.

but this highlights two different setups, you setup for high daily use , I set up for capacity for periods of low or no solar charging I have only converted my caper so far and I have it set up to 9Xs my use for a 24hour period. this 5th wheel I will be putting in 900ah of LFP , so it will be closer to 10x. my solar set up for both is set up to be fully charged by or before 2pm. my camper is actualy fully charge by 10 or 11 am now since I chaged to LFP.

[Microlite_Mike]

Itinerant1 wrote:
Actually 7.9 kwh is one of the better days. Longer daylight hours and sun shining the more power I can purposely use (waste) in the way of the air conditioner. As you know being a veteran to solar... late spring, summer, early fall really isn’t a challenge for off grid living with solar/ batteries. Winter with shorter days, low sun arc and flat mounted panels can be a little more challenging but nothing that a generator can't handle with a 1 or 2 hours run for a hold over charge (20-40% SOC boost) using the lfp batteries in a partial SOC for long periods. 175-225ah is a normal daily use anything over that is air conditioner running, fridge turned over to electric instead of propane, just using any excess power that solar is producing because it's there. 🙂

And on days you don't need the A/C you can always dump the extra power into your water heater and save propane. Then again with almost 8 Kw of power potential you may not even need propane for heating water;)

[3_tons]

Itenerate1: “I believe because the industry is still stuck in dead lead thinking and why not the vast majority of rvs still believe in killing the lead batteries and go buy cheap replacements. Nothing wrong with that because it fits their needs and wallet.”

Well said, and similar to trying to talk someone ‘off the edge’, prior FWC based mindset (a gas gauge like approach) can often be difficult to overcome if not even a mental hindrance when comparing to LFP’s ‘bladder-like’ *characteristics - a rigid mindset that may not serve some FWC users well (reams of past post will easily attest to this….).

***********

* meaning, a relatively flat, stable voltage plateau, uber deep DOD, a FULL daily charge is not a routine objective (unlike FWC, something best avoided except for occasional re-balancing), single stage charging is ideal (tolerant to a relatively wide breadth of charge voltages (upper 13’s not to exceed 14.6v), tolerant towards infrequent charging cycles (a near grid-like experience…), efficient harvest receptivity to better exploit peak harvest hours…

3 tons

[Itinerant1]

Actually 7.9 kwh is one of the better days. Longer daylight hours and sun shining the more power I can purposely use (waste) in the way of the air conditioner. As you know being a veteran to solar... late spring, summer, early fall really isn’t a challenge for off grid living with solar/ batteries. Winter with shorter days, low sun arc and flat mounted panels can be a little more challenging but nothing that a generator can't handle with a 1 or 2 hours run for a hold over charge (20-40% SOC boost) using the lfp batteries in a partial SOC for long periods. 175-225ah is a normal daily use anything over that is air conditioner running, fridge turned over to electric instead of propane, just using any excess power that solar is producing because it's there. 🙂

[pianotuna]

Itinerant1,

Your watts harvested, I think, answered my question. Thanks for taking the time to post the chart.

What I was asking was your daily total consumption. It appears that on the "worst" day 7.9 kwh were harvested and "consumed"?

[Cptnvideo]

I'm set up the same way while plugged in. On my Go-Power inverter, I can adjust load share but it only monitors and limits line 1.

[Itinerant1]

I believe because the industry is still stuck in dead lead thinking and why not the vast majority of rvs still believe in killing the lead batteries and go buy cheap replacements. Nothing wrong with that because it fits their needs and wallet.

I think once you enter into larger battery bank and want to power high draw items you can't beat a programmable inverter/ charger. Yes it cost a little more but the user has entered into a higher cost battery that could be a truely set it and forget system if that fits their wants. Some folks like to tinker with the system.

With my system which has been powered on for 2,279 days (inverter/ charger never been turned off), 2,095 days have been boondocking. The 184 days that were hooked up to a power pole I would turn off the 120v charger but leaver the loadshare set to 15a, 30a or 50a depending on incoming ac power and let the 12v loads be powered from the batteries, solar would top off batteries and float at 13.6v while the 120v is passing through to power the rig. Doing it this way if the rv park did lose power I still have full batteries and I go on enjoying the convenience of everything in the trailer uninterrupted. Which has happened a couple times, once the rv park owners came around and apologized for the power lose but we didn't even know it till I looked at the displays.

Nice having choices.

[time2roll]

Meanwell NPB series charger works well for me.

[Cptnvideo]

Nice chart, Itinerant1.
My daily use is around 220-250ah. But we have a 20cf res fridge.
When boondocking, we all have to conserve water including taking navy showers. But DW and I don't have to conserve electric other than how long the A/C runs.

[jaycocreek]

The weird thing is the vast majority of stand alone lfp chargers are set at 14.6 volts for those that do not use solar or want to just top it off after cloudy days..Expert powers charger is 14.4 but none are adjustable or lower voltage that I know of...

Not much choice for those that don't do solar and rely on a charger for accurate charging..

[Itinerant1]

pianotuna wrote:
Itinerant1,

How do you manage on less than 2304 watt-hours per day? Are the panels actively running the RV during daylight hours? Do you know the total electrical use per day?

I don't know now what you mean by how do I manage on less than 2304wh, 175ah +/- daily? Batteries

Yes, solar is always running loads during the day and the balance of power charging the batteries if needed.

Do you mean electrical use per daylike this?