LiFePo4 lithium battery charging questions - Dutchmen Owners
Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×

Go Back   Dutchmen Owners > Dutchmen Technical | Towing, Maintenance and Repairs > Electrical, Batteries, Charging and Electronics
Click Here to Login
Reply
 
Thread Tools Display Modes
 
Old 01-24-2022, 05:16 PM   #1
Senior Member
 
ewarnerusa's Avatar
 
Join Date: Dec 2011
Location: Helena, MT
Posts: 545
Montana
LiFePo4 lithium battery charging questions

TL DR – I have some questions related to charging 12V LiFePo4 lithium batteries:
*How to best use my solar to charge batteries?
*Assuming I usually keep the lithium batteries at a partial SOC, what if I want occasional 100% SOC?
*What about charging from my tow vehicle?
*What about charging with OEM converter?

Full version:
Hello all. My 10-year-old quick and dirty wiring job for inverter install on my TT is due for an overhaul. My exposed-to-the-elements inverter wiring needs replacing along with the 2 x 6V GC batteries.
Here is what I have now:
*2 x 6V GC batteries in series (~200 Ah total)
*2 x 140 12V solar panels mounted fixed and flat
*Morningstar Tristar PWM controller
*1500 watt PSW inverter
*OEM WFCO converter (55 amp)

I’m thinking that since I want to replace the batteries and some wiring, I want to relocate the batteries from on the tongue to the pass through storage alongside the other electrical components. So I am considering a switch to a single lithium (LiFePo4) 12V battery 100Ah. Current top candidates are Renogy, Battleborn, and Dakota. I am contemplating my charging options if I do this swap.

How to best use my solar to charge batteries? The Morningstar controller is fully programmable and I downloaded a suggested lithium battery charging profile from their website. It relies on the concept of never bringing the lithium battery to 100% SOC as this can be stressful to the lithium battery. From what I’ve learned, lithium works great at partial charge levels vs FLA which should be kept at 100% SOC as much as possible for best health. So the Morningstar config actually does away with the voltage regulating features and changes it to an on-off switching controller via high voltage disconnect (HVD) and reconnect (HVDR) in order to avoid any absorption or float charging. The HVD is 13.8V and HVDR is 13.3V. So controller is in bulk charging mode until the HVD setpoint of 13.8V is reached, then charging is stopped (disconnected) until the voltage drops below 13.3V at which time the charging turns on again and this cycle repeats indefinitely. They say this should get a lithium battery to ~90% SOC and no further, allowing for many cycles without stressing the battery by bringing it to 100% SOC.

But what if I want occasional 100% SOC? My thought is if we’re heading out camping for the long weekend, then I do want to recharge to 100% just prior to and if possible during each camp day. It seems like a few of the lithium battery manuals say that FLA charging profiles that can reach 14.4V and an absorption phase will work fine to fully charge. I think I can put together a “while camping” charging profile based around 14.4V absorption setpoint to accomplish this. 13.3V float?

What about charging from my tow vehicle? My tow vehicle delivers 12V via the trailer plug. No upgrades in wiring or anything there, just whatever the OEM setup is for the 7-pin trailer connector. But I confirm that it brings the trailer battery voltage up to the alternator voltage of 14.2-14.4V. Since this is on the upper end of lithium charging voltage, and considering that I probably don’t want the alternator trying to push 14.4V indefinitely while driving, should I be disconnecting this charging source? Or maybe consider it sort of a topping off charge for the typical 1-2 hr drive to the camp spot?

What about charging with OEM converter? My OEM converter is a WFCO 55 amp model. I have one time ever seen it charge at 14.4V, every other time I have ever used it I see 13.6V. I usually have it switched off via the breaker panel and let solar do the work. I expect I would continue this practice. But it seems like I could use it if I wanted and assuming it continues to only charge at 13.6V, it should be fine for partial charging?

Thanks for any feedback!!
Ed
__________________

__________________
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking
ewarnerusa is offline   Reply With Quote
Old 01-25-2022, 03:19 PM   #2
Senior Member
 
Join Date: Jan 2018
Location: Beaver Dam
Posts: 721
Wisconsin
“TL DR – I have some questions related to charging 12V LiFePo4 lithium batteries:
*How to best use my solar to charge batteries?
*Assuming I usually keep the lithium batteries at a partial SOC, what if I want occasional 100% SOC?
*What about charging from my tow vehicle?
*What about charging with OEM converter?”


For one 100 amp hour Li battery, don’t sweat the small stuff. Everything you have will do just fine. For two 100 amp hour LI. The same advice.

For more than two, consider limiting charge from tow vehicle. Over loaded alternators get hot and cook themselves to death. This happens less with travel trailers than with motor homes. The TT wiring harness tends to limit tow vehicle charging.

It depends on alternator specs and how much your tow vehicle needs as well as house battery charging.

For more than two, consider higher capacity house charger. It is not necessary, but most Li can accept high charge current. This is more important for generator charging when you want to minimize charge time.

Of course all of this depends on the Li battery BMS. I have read up on Battle Born and my advice applies to them.

“…
*2 x 140 12V solar panels mounted fixed and flat
*Morningstar Tristar PWM controller
*1500 watt PSW inverter
*OEM WFCO converter (55 amp)

… I want to relocate the batteries from on the tongue to the pass through storage alongside the other electrical components. So I am considering a switch to a single lithium (LiFePo4) 12V battery 100Ah. Current top candidates are Renogy, Battleborn, and Dakota. I am contemplating my charging options if I do this swap.”


100 amp hours may be a little limiting compared to what you now have. Do you dry camp or boondock? If so, consider 200 amp hours. That will provide more than what you have now.

“How to best use my solar to charge batteries? The Morningstar controller is fully programmable and I downloaded a suggested lithium battery charging profile from their website. It relies on the concept of never bringing the lithium battery to 100% SOC as this can be stressful to the lithium battery.”
..."


Plan looks good. Again, don’t over think it. Li batteries work well and for a long time compared to lead acid. Fully charging to 100% and discharging to 20% works for thousands of cycles. Storing at 50% SoC will increase life. How long do you expect to be still using the system? Do you want to live forever?

“…
But what if I want occasional 100% SOC? My thought is if we’re heading out camping for the long weekend, then I do want to recharge to 100% just prior to and if possible during each camp day. It seems like a few of the lithium battery manuals say that FLA charging profiles that can reach 14.4V and an absorption phase will work fine to fully charge. I think I can put together a “while camping” charging profile based around 14.4V absorption setpoint to accomplish this. 13.3V float?


You are thinking too much like lead acid battery management. Of course if you are going to dry camp, you want 100% charge to start. You only want partial charge for storage or long periods on shore power. Even so, you may never see the Li battery fail.

Battle Born batteries have built in battery management systems. A WFCO will work fine. The new WFCO models have a Lithium setting. The main difference is the Li cycle eliminates the 13.2 volt storage phase that the old WFCO have. Sometimes the max charge voltage is a couple of tenths higher. (Not important).

The Battle Born BMS will disconnect when the battery reaches 100% SoC. At this point while on shore power or generator power, the WFCO powers all 12 volt appliances.

When shore power is disconnected, the BMS automatically reconnects and provides 12 volt power. It is fast enough you will never notice. If the solar provides enough power, the BMS will not reconnect until voltage drops below a preset. I presume the reconnect point is at or near 13.2 volts, so that is why the new WFCO eliminate the storage voltage for Li.

“What about charging from my tow vehicle? My tow vehicle delivers 12V via the trailer plug. No upgrades in wiring or anything there, just whatever the OEM setup is for the 7-pin trailer connector. But I confirm that it brings the trailer battery voltage up to the alternator voltage of 14.2-14.4V. Since this is on the upper end of lithium charging voltage, and considering that I probably don’t want the alternator trying to push 14.4V indefinitely while driving, should I be disconnecting this charging source? Or maybe consider it sort of a topping off charge for the typical 1-2 hr drive to the camp spot?"

Again, don’t over think it. Battle Born batteries have a built in BMS and will take care of themselves. If you are building your own BMS system, there are a lot of technical issues to consider. The BB BMS will disconnect when appropriate.

“What about charging with OEM converter? My OEM converter is a WFCO 55 amp model. I have one time ever seen it charge at 14.4V, every other time I have ever used it I see 13.6V. I usually have it switched off via the breaker panel and let solar do the work. I expect I would continue this practice. But it seems like I could use it if I wanted and assuming it continues to only charge at 13.6V, it should be fine for partial charging?”

All covered above. Don’t worry about it.

WFCO only reaches 14.4 volts in the first 4 hours of charging, and then, only if battery absorption is less than 55 amps. After 4 hours, voltage drops to 13.6. After 4 days in storage the WFCO drops to 13.2 volts. The BB BMS will disconnect when it is full and not reconnect before voltage drops below internal preset.

55 amps for 4 hours is 220 amp hours. It is more than enough to charge two 100 amp hour Battle Born batteries. BMS will disconnect. WFCO will drop to 13.6 volts and supply all 12 volt appliances.

LiPO4 are great RV house batteries. The best have built in BMS. The advantages mean you have much less to worry about. Read the instructions for the battery you buy. Enjoy your camping experience.
__________________

__________________
Paul Bristol
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015
persistent is offline   Reply With Quote
Old 01-25-2022, 03:47 PM   #3
Senior Member
 
ewarnerusa's Avatar
 
Join Date: Dec 2011
Location: Helena, MT
Posts: 545
Montana
Thanks Paul! We 100% boondock, I have only ever plugged into services once when I loaned my camper out to my parents during a hospital stay and they had RV full service spots at the hospital for patients. Our current 100 Ah of usable capacity with the 2x6V has never left us short, so for now I feel OK with a 100 Ah drop in replacement.
You're right, I'm over thinking this quite a bit! It's a high dollar purchase though, so I want to make sure I've got the details down. :-)
__________________
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking
ewarnerusa is offline   Reply With Quote
Old 01-25-2022, 05:28 PM   #4
Senior Member
 
ewarnerusa's Avatar
 
Join Date: Dec 2011
Location: Helena, MT
Posts: 545
Montana
Caveat to my claim, I have of course plugged the camper into shore power before when at home in storage or to the generator during the heat of the day for using the air conditioner. But even then, I usually let the solar take care of the battery maintenance and leave the converter off.
__________________
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking
ewarnerusa is offline   Reply With Quote
Old 01-30-2022, 01:34 AM   #5
Senior Member
 
Join Date: Jan 2019
Location: Grand Junction
Posts: 84
Colorado
Battle Born Charging

I personally designed and installed over 100 RV solar systems last year, most of them with Battle Borns. Here are a few tips...

1) Battle Borns need to be taken over 14.2V for 30min every so often to allow the internal BMS balancer to balance the cells. Once a month is fine.
2) The older WFCO will not charge a Battle Born. If the LiFePO4 battery is over 13.2V, which it almost always is, the WFCO thinks it's full and won't even turn on.
3) The fuse will blow in the 7-way plug circuit long before you can overheat your alternator.
4) Keeping your batteries between 20% and 80% will give you a little better life, but the batteries will probably last 15 years anyway.
5) You need a current shunt battery monitor to determine the state-of-charge (SOC) of a LiFePO4 battery, since the voltage profile is quite flat.
6) MPPT solar charge controllers do make a significant difference in the amount of power you can pull out of a solar panel. They are better for flat panels, for cloudy days, for hot days, for cold days, all the time. Well worth the extra money.

Hope this is helpful.

Leisure-Lee
leisuresolar@gmail.com is offline   Reply With Quote
Old 01-30-2022, 02:30 PM   #6
Senior Member
 
Join Date: Jan 2018
Location: Beaver Dam
Posts: 721
Wisconsin
Battle Born says WFCO chargers are compatible.
https://battlebornbatteries.com/char...ibility-table/

WFCO publishes "Theory of Operation". Their design now includes a "Li" button. However, the old "Theory of Operation" was very similar to the new one.
https://wfcoelectronics.com/wp-conte...eration-v2.pdf

13.2 volts is the "strorage" voltage. Many owners have looked for it and not found it. That is because it most often is providing 13.6 volts. It only drops to 13.2 volts under certain limited "storage" conditions.

The WFCO does measure current and voltage. When current drops low enough, for long enough, the voltage will switch to 13.2 volts. If the current changes even a little, like turning on a 12 volt light, the WFCO will switch back to 13.6 volts.

Lithium batteries do not need any current or voltage during storage. Letting the cell voltages drop a little during storage actually improves service life. The Battle Born BMS actually disconnects the terminal voltage from the cell banks as each cell bank reaches full charge. The BMS does not reconnect until terminal voltage drops below a preset voltage. So, your converter can provide all the 12 volt power you need and the batteries can idle until you need them.

The WFCO does not regulate current except when current tries to exceed the maximum it is capable of. So, it does not regulate current at 1.5 amps at any time. As long as the Li battery is drawing significant current, the charge voltage will remain at 13.6 volts.

The WFCO regulates voltage like most other lead acid chargers. It changes voltage between 13.6, 13.2, and 14.4 volts depending on measured current and battery voltage.

The "old" WFCO will charge one or two Battle Born 100 amp hour Li batteries just fine. The key is the battery bank needs to be fully charged within the 4 hour window that the WFCO will provide 14.4 volts charge.

A 30 amp WFCO will charge a 100 amp hour Battle Born with in 4 hours.
A 60 amp WFCO will charge two 100 amp hour Battle Born batteries in 4 hours.
A 90 amp WFCO will charge three 100 amp hour Battle Born Batteries in 4 hours.

The "new" WFCO works just the same, except, it will not drop to 13.2 volts "storage" condition when the Li switch is set to LI.

I have not studied the "new" theory of operation. I may be surprised to see other changes. Feel free to point them out to me.

I wish you good luck and happy trails ahead!
__________________
Paul Bristol
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015
persistent is offline   Reply With Quote
Old 01-30-2022, 02:56 PM   #7
Senior Member
 
Join Date: Jun 2017
Location: Wesley Chapel
Posts: 2,679
Florida
You guys talked about these things so much I decided to see if I could upgrade to them. WOW, THEY ARE REALLY EXPENSIVE! are they really worth it?

Seems like a great topic for the next rv life newsletter!
franktafl is offline   Reply With Quote
Old 01-30-2022, 03:03 PM   #8
Senior Member
 
Join Date: Jan 2018
Location: Beaver Dam
Posts: 721
Wisconsin
Quote:
Originally Posted by franktafl View Post
You guys talked about these things so much I decided to see if I could upgrade to them. WOW, THEY ARE REALLY EXPENSIVE! are they really worth it?

Seems like a great topic for the next rv life newsletter!
I do not have Battle Born lithium batteries in my TT. I do have an "old" style WFCO. I did study the BB performance and decided that for me, I would reconsider upgrading when my current AGM bank no longer meets my needs.

For the most part I expect my AGM's to be adequate for the remainder of my TT's service life.

Different situations have different "optimum" results.
__________________
Paul Bristol
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015
persistent is offline   Reply With Quote
Old 01-31-2022, 05:51 PM   #9
Senior Member
 
ewarnerusa's Avatar
 
Join Date: Dec 2011
Location: Helena, MT
Posts: 545
Montana
I'm at a point where I need to redo some wiring and also replace the current 2x6V GC lead acid batteries. Since I need to do some work and buy some new stuff, I'm leaning towards the upgrade.
@persistent, your link to the Battleborn page about WFCO converters also had a nice link on charge controller settings for my Morningstar Tri-star. I'll keep their suggested parameters in mind.
https://battlebornbatteries.com/set-...-born-battery/
__________________
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking
ewarnerusa is offline   Reply With Quote
Old 01-31-2022, 06:34 PM   #10
Senior Member
 
Join Date: Jan 2018
Location: Beaver Dam
Posts: 721
Wisconsin
Good Advice from Battle Born Batteries

It pays to know how the Li battery BMS works as well as the charger. Battle Born clearly shows an interest in learning how other manufactures chargers work with their BMS.
__________________
Paul Bristol
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015
persistent is offline   Reply With Quote
Old 05-11-2022, 03:55 PM   #11
Senior Member
 
ewarnerusa's Avatar
 
Join Date: Dec 2011
Location: Helena, MT
Posts: 545
Montana
Just to provide a conclusion to this thread, I ultimately did not get the LiPO4 battery. Several "pretend camping" nights in the driveway with the kids happened in early spring and I ran off battery power with heavy furnace use. The current 2x 6V GC batteries performed great, so I felt like replacing them at this point was throwing away money. So I undertook the wiring upgrade that inspired this research in the first place and I'm happy with the way that turned out. Looking forward to "real" camping this season!
Here's a pic of the new outside battery box that holds both 6V in one box instead of 2 separate. New 1/0 gauge positive and negative cables replacing the minor birds nest of connections that used to be there. Loom protection added to the new wiring. There is a cover for the battery case.


Also installed some coulomb counting gauges to monitor current from the solar panels in green on the right and net amps from the batteries on the left.
__________________
2012 Aspen Trail 2710BH | 280 watts of solar on the roof | 2x6V GC batteries | 100% LED lighting | 1500 & 300 watt PSW inverters | so far strictly boondocking
ewarnerusa is offline   Reply With Quote
Old 05-12-2022, 02:17 PM   #12
Senior Member
 
Join Date: Jan 2018
Location: Beaver Dam
Posts: 721
Wisconsin
Thank you so much for posting a closing update!
__________________

__________________
Paul Bristol
Dutchman Kodiak Cub KD176RD 2018
Nissan Pathfinder 2015
persistent is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Dutchmen RV or any of its affiliates. This is an independent, unofficial site.


All times are GMT. The time now is 08:49 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright 2020 Social Knowledge, LLC All Rights Reserved.
×