Charging LiFePO4 Batteries
Every day we get questions about charging LiFePO4 batteries. We decided to review some products that work great with our Battle Born LiFePO4 batteries. To begin the series we will cover some of the basics of charging batteries and then cover the products in other segments.
Charging a battery basically means applying an external voltage to drive current from the anode to the cathode of the battery. The charger acts like a pump – pumping current upstream, opposite the normal direction of current flow when the battery discharges. When the charger’s applied voltage is higher than the open circuit battery voltage, then the charging current flows. During this process, the battery open circuit voltage increases, approaching the applied voltage of the charger.
The charger can behave in several different ways during the charging process. First the charger can steadily increase its voltage in order to keep the current flow constant. This is the first stage of the charging process – typically called the “bulk” charging stage. During this stage, the charger adjusts its applied voltage to deliver the maximum current to the battery. For example, a 10 Amp charger will deliver its maximum of 10 Amps during this bulk charging stage, and the applied voltage will increase up to a maximum voltage, or “bulk voltage”.
Once the bulk voltage is reached, the charger enters a second stage, called the “absorption” charging stage. During absorption, the charger applies a constant voltage, called the “absorption voltage”. As the battery open circuit voltage approaches the absorption voltage, the current flow steadily decreases down to zero.
At this point the battery is fully charged. However, a lead acid battery will rapidly lose charge when the charger is disconnected. So, instead of turning off, the charger enters a third stage called the “float” stage, in which the charger drops to a lower voltage and holds at that voltage. The point of this stage is to keep the battery topped off, and account for the fact that lead acid batteries tend to drain, even when there is no load connected.
These stages combined sequentially form what is commonly called the “charging algorithm”. A battery charger may generally be classified by a charging current (i.e. the max charging current) and a target battery voltage (12V, 24V, 36V, 48V, etc.). But chargers may also include multiple charging algorithms (typically classified as “AGM”, “SLA”, “Gel”, “Wet”, etc.). A closer look reveals that each algorithm has its own unique parameters, including:
• Bulk voltage
• Absorption voltage
• Absorption time
• Float Voltage
Among charging algorithms for lead acid batteries, there is a wide variation for these values. The bulk and absorption voltages typically vary between 14.0 and 14.8 V and the float can vary between 13.2 and 13.8 V. The 12V Battle Born batteries sit comfortably right in the middle of these ranges. We recommend a bulk and absorption voltage of 14.4V. A float is unnecessary, since Li-ion batteries do not leak charge, but a floating voltage under 13.6V is fine.
Here are a few of our FAQ videos that talk about charging LiFePO4 batteries.
In this blog series, we will post the results of our tests for a variety of LiFePO4 chargers – including converters, inverter/chargers, and solar charge controllers. In each case, we will report on the uniqueness of the charging algorithms for each brand, explore the efficacy of using the factory default settings for charging Battle Born Batteries, and determine what can be done to achieve the optimal settings.
Since this is a work in progress, please contact us at any time at 855-292-2831, and we would be happy to address your concerns about charging LiFePO4 batteries.
Ming Dinh | Aug 13, 2017 at 1:45 pm
Hello,
Do you sell smaller batteries? I am looking for something in the range of a 50ah, 12V battery.
Do you ship to Vancouver, Canada, and can you supply an estimated shipping cost?
Thank you,
Ming
Will Olney | Aug 16, 2017 at 10:18 am
We will be releasing a 12v 50ah in the next week keep an eye out on our Facebook page and website.
Crosby Grindle | Dec 27, 2017 at 8:57 pm
What is the reserve capacity of your batteries? I may not be using the correct term but battery manufacturers often specify the amount of total capacity available before there is significant voltage drop. I know this capacity is typically much better with LiFe batteries – sometimes 90%. Can you provide similar information about your batteries?
Will Olney | Dec 28, 2017 at 8:09 am
Hello Crosby,
Our batteries don’t necessarily have a reserve capacity that is more of a term used with lead acid batteries, but you are able to use a full 100% of the batteries capacity. please give us a call if you have any other questions.
775 221 8897
John Custin | Aug 8, 2019 at 1:18 am
Can I charge a lithium Iron phosphate battery from a portable generator? My generator manual says I can use the 12v 8.5 amp output on the generator to charge a battery but this seems too low amperage to charge a lithium battery. Dunno why my generator has such a low amperage for charging 12vdc battery
Dianne F | Aug 22, 2019 at 8:11 am
Hi John,
Your generator will provide 120 volts into your electrical system, the converter/charger is responsible for converting it into the proper 12 volt profile to charge the batteries. As long as your charging method is compatible with lithium then you should be able to quickly and completely charge our batteries. The converters amperage rating will determine how fast the battery will charge, the higher the amperage the faster the charge. Remember that our recommended charge rate is .5 c, that’s 50 amps per 100 ah battery.
Thank you
CLIFFORD G MILLER | Jul 9, 2018 at 9:30 pm
When charging a smaller ah lithium battery such as a 7 to 9 ah do you use the same settings on a programmable ac/dc power converter as you would on a larger ah lithium battery?
Sean Nichols | Aug 3, 2018 at 8:22 am
Depends on the chemistry. Best thing to do is contact the mfg of the battery and ask them for the charging parameters.
Bradley Pfanner | Aug 12, 2018 at 4:20 pm
Could I charge this battery with jumper cables connected to a running car battery?
Dianne F | Aug 13, 2018 at 10:36 am
Bradley,
This is a possiblity as long as you don’t exceed 100ah. If you have anymore questions please feel free to call us 855-292-2831 or email us at [email protected]
HT | Nov 4, 2018 at 7:00 am
Please tell me the optimum AMPERAGE level for charging Battle Born 12v 100ah batteries. Thanks.
Dianne F | Nov 8, 2018 at 8:54 am
Hi there, I will include the criteria of amperage level for our batteries:
100 Amp Continuous Current
200 Amp Surge Current (30 Seconds)
If you have any questions, please let me know. You are welcome to reach us at [email protected] or give us a call at 855.292.2831. Thanks!
zoltan szabatin | Nov 14, 2018 at 6:33 am
Hi
I could be wrong, this is what I learned : problem with a”normal” RV battery charger is,:having a float mode?
Dianne F | Nov 16, 2018 at 2:53 pm
Zoltan,
That’s a good questions. Our batteries do not require a float charge. But they can be in float mode as long as the float is around 13.6, it is OK for the batteries to float around that voltage.
Jim Rout | Dec 23, 2018 at 8:05 am
We currently use 2 external Alphacell 220 GXL 109AH batteries in serial, connected to an APC Smart-UPS 700. We are looking to replace the 220GXL batteries but keep the APC-UPS. We remove the internal battery from the APC-UPS. Will a LiFePO4 battery work in this instance as a replacement for the Alphacell 220 GXL lead acid batteries? We have to replace about 20 of these batteries.
In some instances we use a single 220 GXL connected to an inverter and a standard marine battery charger. This is then connected to a transfer switch which switches from wall outlet power to inverter power in the event of a power failure. Can the LiFePO4 batteries be charged with a standard marine battery charger ?
Dianne F | Jan 3, 2019 at 8:39 am
Hello Jim,
lithium batteries power 12 volt devices with the proper voltage just as a regular lead acid battery so running devices will not be a problem. Charging Lithium batteries requires a voltage in between 14.2-14.6 volts for bulk/absorption, 13.6 or lower for float and should not have an equalization stage. Typical lead acid chargers can work in some instances but we would have to get the model # for your marine battery charger and check the settings for compatibility. Please give us a call at your earliest convenience so we can go over the details. 855-292-2831
Thank you,
Wayne Robey | Jan 5, 2019 at 7:02 pm
The Pb battery chargers I know of have a fixed absorption time (which may be programmable) BUT it seems that the best way to charge a Li battery is to switch from absorption to float when the charging current reaches a prescribed value, so I have 2 questions: Do you know of any PV powered chargers that can switch from absorption to float using a external signal (logic level input) and if using a constant but programmable absorption time, what is a good time (for a specific voltage)?
Dianne F | Jan 7, 2019 at 5:42 pm
Hi Wayne,
The Victron MPPT charge controllers allow you to set the absorption time(and voltage 14.4v) to the desired level. In the case with our lithium batteries its about 20 minutes per battery. You can also set the float voltage to the recommended 13.6v after the absorption time is achieved.
Thank you,
John Bell | Jan 7, 2019 at 9:20 pm
I frequently use my RV in below freezing conditions in the winter. I plan on an inside, normally heated battery location, however, their are times when the battery temp might drop below freezing. I understand that your internal BMS has a low temp disconnect to prevent damaging the cells when charging when the batteries are too cold. Could you elaborate on the process of the disconnect/reconnect if this occurs.. In my application would you advise that I add external charger disconnects to prevent accidental charging, such as from solar panels, until I’m sure the battery warms above freezing? Or will the BMS provide this function?
William S. | Jan 10, 2019 at 11:18 am
I have 6 12V 200AH lithium ion batteries, and I was wondering what would be the best way to charge them all at once, and how many Amps and volts my charger would have to put out to charge them in at least 10 hours from being completely depleted.
Dianne F | Jan 10, 2019 at 1:10 pm
Hello William,
We don’t make 200AH batteries, so I’m assuming these are another manufacturers batteries. I would check with your battery manufacturer to answer this question for you. I can only speak for our 100AH batteries.
John Bell | Jan 15, 2019 at 7:04 am
Recently installed my 2 100AH Battleborn Batteries in my RV and programmed my solar and inverter/charger to your recommended specs. In case you missed my earlier post, regarding the low temp disconnect of the internal BMS. My question is weather you recommend I install additional charger disconnects to protect the battery from charging in freezing conditions or is the BMS designed to disconnect and reconnect when temp rises to a safe level. Thanks.
Dianne F | Jan 15, 2019 at 8:39 am
Hello John,
The BMS is programed to handle temperature compensation. No need to add a battery disconnect for charging. When the BMS senses the temperature is below 25 degrees F, it will not let the battery accept a charge. Once the temperature is back up above 25 degrees F, the battery will be able to accept a charge again.
James Griffith | Jan 17, 2019 at 11:54 am
What percent increase in battery life would you expect if your battery were only charged in the range 25-35F vs only charged in the range 35-45F?
Dianne F | Jan 17, 2019 at 3:14 pm
James,
The colder the temperatures you are charge in, the less life expectancy you will incur. We don’t have a specific % increase or decrease calculation for these temperatures but around 70F is optimal for maximum life expectancy.
Thank you,
Jeff B Bohrer | Jan 23, 2019 at 10:03 pm
Sorry I forgot to include my name and email on the first comment I sent.
I just received 3 of your 100 ah 12v batteries, do I need to charge them before installing or using them?
If I decide to add another in a few months, are there any special procedures that I need to follow?
Dianne F | Jan 24, 2019 at 11:17 am
Hi Jeff,
We always recommend charging the batteries completely before the initial use. This becomes even more important when connecting batteries in series.
Adding another battery in the future will not be an issue, again just bring all the batteries to a full state of charge before using.
Thank you,
tim conley | Mar 17, 2019 at 4:18 am
Hello
can I leave my rv plugged into shore power for an extended period of time with out harming the batteries.
Dianne F | Mar 20, 2019 at 8:27 pm
Hi Tim,
If you are storing your rv and wish to have it plugged in, we would recommend a float voltage of 13.6 volts. If you have a higher voltage applied in float(such as 14.6) then we would recommend that this be no longer than 3 weeks at a time.
Thanks,
Laura Hoey | Apr 24, 2019 at 2:14 pm
What would be considered the resting voltage of a fully charged Lithium battery, with no load connected? I’m trying to ascertain if my (non-Battleborn) battery has a bad cell, or a bad bms. Thanks~
Dianne F | Apr 24, 2019 at 4:46 pm
Hi Laura,
The resting voltage of a fully charged Battle Born Battery is 13.5 to 13.6 volts. You may want to contact the manufacturer of your other lithium battery to see if it is the same per their specs.
Thanks,
Andrew Eisenburg | Jul 8, 2019 at 7:10 pm
I am wondering about the ideal amount of wattage of the charging side of the system? What is the ideal amount of charging wattage per 100ah of battery to get the longest service life? I plan on putting together a 250ah system.
Dianne F | Jul 16, 2019 at 5:04 pm
Hi Andrew,
It really depends on how much power you are using in a day as to how much solar you will need to restore the power that you are using out of your battery. Generally speaking, 350 watts of solar should restore one of our batteries from empty to full in one day of direct unobstructed sunlight.
Thank you,
Mark Kramer | Apr 27, 2019 at 4:22 pm
Hello,
Can the Battle Born 100ah lithium 12V batteries be charged off of the alternator using a battery isolator? I assume as long as the max output of the alternator does not exceed 100amps of continuous current?
Dianne F | Apr 29, 2019 at 10:44 am
Hi Mark, Yes our batteries can be charged off of the alternator using the Battery Isolator within our Accessories. Give us a call for more information on this, 855.292.2831! Thank you and have a great day.
Russell Miller | May 1, 2019 at 6:36 am
Hello,
I have a 2018 Toyota Rav4 hybrid, I am considering replacing the original 12v Aux. battery with your Lith. Battery. Or adding a 2nd battery, (yours), wired in parallel or connected to the load and separately connected to the car through say the 12v cigar lighter. I do know not much about the Rav4 hybrid elect. system except that it does not have an Alt. but charges the Aux. battery from the Traction battery. The charge Amp. is low 15 or less. in normal driving it seems to stay at 14.2v.
Would your batteries work under either or both senarios, or what changes should should I make to accomplish either?
Dianne F | May 2, 2019 at 10:45 am
Hi Russell,
There are many different factors in play with this system and it will require a phone conversation in order to work out the details.
Please give us a call at 775-622-3448
Thanks,
David Frye | Jun 21, 2019 at 7:40 am
Watching videos about litium batteries, some concern is expressed for charging when temperatures are high. An equipment shed can get pretty warm. And in a grid down situation, even a normally cool compartment will get hot in the summer and most of the year here in Florida. What are the ramification of charging when the ambient temps are in the 90s and the sun is beating down on everything?
Dianne F | Jun 24, 2019 at 9:45 pm
Hi David,
Here are some temperature parameters for our batteries that should help with your question:
High temperature: > 135F The BMS will not allow a charging or discharging current.
Low temperature: < 25F The BMS will not allow a charging current. Charging current will be allowed again at 32F. We recommend not to use the batteries in temperatures under -4F Cold weather storage The storage temperature range is -10F to 140F. We recommend bringing the battle born batteries to a 100% charge and then disconnecting them completely for storage. After 6 months in storage you should still have 75-80% charged batteries. Storing batteries in sub zero weather(-15 or more) has the potential to crack the abs and more importantly could causes a faster loss of capacity, in some cases drastically more than the typical 2-4% per month loss. Charging our lithium batteries in cold weather We have an adhesive backed heating wrap that runs off of a 12 v source and works very well. It has a temperature sensor that allows it to turn on at 34F and stays on until the temperature rises above 45F. Heating wrap draws 30 watts/2.5-3 amps and is 3/16 of an inch thick. Hope this helps, thank you.
Steve Guthrie | Jun 23, 2019 at 1:51 pm
My inverter / Charger allows a 2 stage charge, no float. there is also a setting for a recharge voltage so that it will start the charge process once the discharge falls below this level. What do you recommend setting this at?
I also have a solar system installed that has been topping off the batteries when the sun shines, that is why I chose the 2 stage charge function.
Dianne F | Jun 24, 2019 at 9:48 pm
Hi Steve,
We usually recommend a recharge voltage setting of 13.3 volts and this means that at about 70% full the charger will rebulk and bring the batteries back up to a full state of charge.
Thank you,
Joshua | Jun 23, 2019 at 7:34 pm
Im wondering if the BMS in these batteries top balance or bottom balance or some other way of balancing. I do not use the full capacity of my 12v 100ah lifepo4 and although right now my solar mppt charge controller is set to Lithium and charging at 14.4 volts I am wondering if I could lower the setting slightly to 14.2 or 14.3 volts, thus charging to slightly lower than 100% capacity since I heard this increases the overall lifespan and cycle life of the battery. I do this with my 36v ebike 18650 battery pack where I charge to 90%. but since some batteries are top balancing once in a while it is good to charge to 100%. What do you think for battle born being charged to 14.3v….. Thanks
Dianne F | Jun 24, 2019 at 9:53 pm
Hi Joshua,
A voltage of over 14.2 should give you a full state of charge and there is no need to set the charger to less than this. when 14 volts is reached then the passive balancing is activated and will keep the batteries in a balanced state over time.
The largest impact to decreased longevity is not from bringing the batteries to empty or from charging back up to 100%. It is from charging at a rate higher than .5c (50 amps for a 100ah battery), this will have the biggest effect on diminished lifespan.
Thank you,
Dianne F | Jun 24, 2019 at 9:06 pm
Hello Tyler,
Yes the CC/CV settings work great with our batteries and the parameters that Magnum gave you are perfectly acceptable. The recommended charge rate for our batteries is .5c, meaning for every 100 ah battery in parallel you would not want to go much more than 50 amps.
Thank you,
Jeremy | Jun 27, 2019 at 4:12 pm
I’m interested in a large bank of batteries to power the RV air conditioner with battery power. Assuming I have 800ah, how long would it take to charge the bank from either the alternator (with proper charger) or from 3.2 kw Onan diesel generator
Dianne F | Jun 27, 2019 at 4:41 pm
Hello,
The amount of time that its going to take to charge is all going to depend on the amperage of the charging methods.
Patrik Eriksson | Jun 27, 2019 at 4:15 pm
Hi! I have a Xantrex Link 2000 battery monitoring coupled with the Freedom combi charger/inverter.
Is there a suitable setting for charging your LiFEPO4 batteries?
Dianne F | Jun 27, 2019 at 4:36 pm
Hello,
Yes your battery monitor will work. You’ll have to enter the charging parameters below.
12 V
Bulk/absorb 14.2 – 14.6 Volts(we usually recommend 14.4)
float 13.6 Volts or lower
No equalization(or set it to 14.4v), no temperature compensation and absorption time is 20 minutes per battery(if its an option).
Kyli Tanner | Jul 13, 2019 at 11:11 am
I have an old trace c30A+ it seems top only have low and high voltage disconnect adjustments… can I user that whith one of your 100ah lifep04’s?
Dianne F | Jul 16, 2019 at 5:14 pm
Hi Kyli,
It doesn’t look like this is a compatible charger, we would recommend a lithium specific charger for your battle born batteries. We have many on our website but feel free to give us a call if you would like more details.
Thank you,
Dr. William J. Schmidt | Jul 14, 2019 at 5:00 pm
I’m building some remote water pump stations for the Caribbean powered by LiFePo batteries. They are being recharged by a solar panel and solar charger (made for LiFePo batteries). However, there is a scenario that I’m concerned about… that is operation after a day or string of days where the battery charging is less than sufficient to reach full charge. I will probably need to design a voltage cut-in/cut-off module to protect the batteries from permanent damage. What are the usual cut-off and cut-in voltages for LiFePo batteries?
Dianne F | Jul 16, 2019 at 5:19 pm
Hi William,
Our batteries have an internal BMS that protects the batteries from damage by shutting down at 10.5 volts. After this low voltage cutoff is activated then a direct 12 volt source will need to be applied in order for the batteries to re-initialize or wake the battery back up. We also have a high voltage cut off at 14.7 volts.
Hope this helps, thanks.
Richard Sanford | Jul 22, 2019 at 7:46 am
I just purchased 4 12V 100 amp batteries for my 2017 Winnebago Sunstar LX 35F replacing the old lead acid batteries that came with the coach. I know I can drop the new batteries in using a parallel connection setup. I also was told I needed LI-BIM 225 battery isolator that recognizes lithium batteries. The coach has an automatic dual charge controller, auxiliary start circuit, 2K-watt AC/DC inverter and auto start generator. I was told I could just disconnect the cables from the existing BIM and connect them to the new one. Sounds pretty straight forward but I’m not sure where to find the existing battery isolator assuming there is one. Can you give me the info on this setup? I also heard the BIM225 doesn’t come with directions…
Thanks,
Richard Sanford
Dianne F | Jul 22, 2019 at 9:59 am
Hi Richard, we suggest you give us a call at 855.292.2831 so we can give you some better help and ask any other questions we may have. We have some diagrams for the BIM that we’d love to send you to take a look at, just remind us when you give us a call thanks!
Kevin Turvey | Jul 24, 2019 at 9:51 am
Hello,
I’m considering purchasing the Aims PICOGLF20W12V120VR 2000w inverter/charger to use with my future two 100ah batteries. My only concern is the setting for lithium batteries are “boost/vdc 14.4v and float/vdc 14.4v. Will this work with your batteries?
Thank you
Dianne F | Jul 24, 2019 at 10:42 am
Hi Kevin,
The “boost/bulk/absorb” setting is fine at anywhere between 14.2-14.6 volts for any kind of charging method. If you have a float voltage that is above 13.6 on a device, then we recommend it not be connected to our batteries for more than about 3 weeks at a time(if you are not using any power out of the battery during this time).
Thank you,
RUTHIE C ORIEL | Jul 25, 2019 at 7:33 pm
How does being charged by a tow vehicle’s alternator effect the battle born batteries installed a travel trailer?
Dianne F | Jul 26, 2019 at 1:31 pm
Hi Ruthie,
Most customers get a small amount of charge from the vehicles alternator on a travel trailer. We usually see around 5 amps or so through the 7 pin trailer connectors as these wires are very thin and will not transfer power very efficiently or quickly. Alternator voltage is around the 14.4 range which is great for lithium batteries but the length of wire and the gauge is typically the limiting factor.
Thank you,
Rob Duran | Sep 8, 2019 at 8:58 pm
Hi I a confused on the fiction of the BMS pertaining to low voltage disconnect. My 2 12v 55ah LiFePo batteries connected in parallel during a capacity test dropped below 9 volts and they did not disconnect. They continued to power the inverter but then started climbing back up to over 10v then going down again. Is this normal for the BMS to not shut the batteries down? I assumed it would shut down power at 9-10 volts but didn’t. I’m worried it may damage the batteries if it discharged without disconnecting. Thanks for your opinion on this.
Dianne F | Sep 17, 2019 at 12:05 pm
Hello Rob,
At the moment we don’t produce a 55 ah battery, are these Battle Born batteries? If so then they would be the 12 volt 50 ah version, please give us a call so that we can go over your system components and do some further troubleshooting. If these batteries are a different brand then Battle Born then you may want to contact that specific manufacturer for more help.
855-292-2831
Thank you,
Global Imports, Inc. | Sep 15, 2019 at 5:46 am
This was an awesome post! Thank you for sharing your best knowledge about batteries. People will find best guide from this blog.