Basic Care and Trouble Shooting of a LiFePO4 E-bike Battery

July 19, 2012

A common choice for powering a hub motor kit is a LiFePO4 battery pack (Lithium-Iron-Phosphate).  Brand names include Pingbattery, and V Power HK, and there are no-name versions known as a duct tape LiFePO4 pack. Many people new to E-bikes make easily avoidable and simple mistakes that lead to problems, and sometimes even battery death.

Battery break-in of new packs

The brand new cells may or may not need a break-in. There is no way to really tell if they do or do not, so follow this simple break-in procedure to be sure. When the battery arrives, plug in the charger to the battery, then plug the charger to the wall, and observe how it reacts. It should display a red light, indicating it’s charging. After awhile, it should change to a green light indicating it’s charged. Leave it plugged in for about an hour or more after the green light turns on. The charger may cycle from red to green periodically, as the battery management system balances the battery.

Pingbatterys battery management system (BMS) will have a row of LED’s visible. The battery is fully charged and balanced when all the LED’s are lit. The BMS will have 12 LED’sfor a 36V battery, and 16 for a 48V battery.  For others, just make sure to charge it long enough to stop cycling from on to off and on again. Here is a Pingbattery battery management while charging, and at 54V. I have the voltage displayed on a cheap voltmeter, it’s not part of the BMS.



Here is the same battery at 58V, with nearly all the BMS lights shining.



Now run some shallow discharges.  If you have the bike ready to roll, ride around the block, then put it back on the charger. If the bike is not ready, the battery can be stored safely for a week or two. The idea is to get the cells used to taking a full charge, and balancing. If your BMS is the type with the LED’s, you can actually see the battery perk up and balance faster. Usually about 5-6 cycles like this does the trick. Your LiFePO4 bike battery is now ready for riding, and should be safe to ride for long distances with no problems from one or two undercharged cells causing a reduced pack capacity.

Charging your battery

Charging is simple, plug in the charger provided with the battery. Unplug later, when the green light has turned on.  There is little reason to use timers, or get up in the night to unplug the charger. When the green light is on, the charger uses very little power, and is not overcharging the battery. The BMS will discharge any high voltage cell groups to the proper voltage. Leaving it charging overnight will just give it more time for the battery management system to balance the battery.

Balanced is when all the cells are charged to their full capacity. The battery management system will start discharging the over-full cells when the charger turns off, showing a green light. Then later, the charger will go red and continue to charge the lower voltage cells in the pack. This repeats till the battery is balanced.

Don’t worry about this process wasting cycles. If you discharge the battery 100%, (meaning, you ride until the BMS shuts off the battery) that is one cycle. If you routinely discharge less than that, you simply get more cycles. Limiting the discharge depth to 80% tends to lead to a better balanced battery that takes less time to recharge, and may lead to even more cycles than the seller promised. So charge whenever you can, and don’t worry about trying to discharge deeper to get 100% of the rated cycle life.

Not all battery chargers are built to withstand severe vibration. So if you do carry the charger around, carry it in a way that limits the bumps and bounces on the road, such as in a knapsack. Best of all, stash an extra charger at your work if you can.

Turning your E-bike on and off

If your bikes controller has an on off switch, you do not have to unplug the battery every time you park it. But if there is no switch, you should unplug the battery. If the controller is left turned on, it will drain the battery at a rate of about 3-watts. About 7 days in storage with the controller turned on would completely drain the battery, risking severe damage if your BMS does not shut the pack down.

When you plug in the controller, the capacitors inside pull a rush of current, which causes a large spark. This spark is generally harmless with small controllers for 1000W or less. If the spark damages a particularly cheap connector, then replacing the connectors with 45-amp Anderson Powerpole connectors is one way to simply solve that problem.  Power poles are designed to handle the connection spark with no damage.

 Protective Battery Box

Many of the larger LiFePO4 E-bike batteries do not come in a protective box. You should make something to give the battery some extra protection in case you crash, or just knock over the bike. A tight fitting custom plastic battery cover can also prevent chafing when the battery moves slightly inside it’s box or bag that you are carrying it in.  Coroplast is a very easy material to work with. Cut and tape, to make a tight fitting box around the battery that will not allow the pack to chafe. All wear and tear is then transferred to the battery cover, instead of wearing on the battery itself.  Other materials work well too. I have used an aluminum cookie sheet to make a battery cover.  Others have used peel and stick floor tiles to give a battery a bit more durable outer shell.

Here is how I made a battery cover for my 48V / 15-Ah LiFePO4 ping battery.
The material chosen was a lid to a large plastic storage tote.



The battery is placed on the material, and a line traced around it.  The plastic was cut at the corners and folded up into a box with 5 sides.  Extra material is left at the corners, and folded over to strengthen the corners.  Extra material left on the long sides is folded over to protect most of the top.



Then the battery is placed on the cover and the sides folded in and taped as tight as possible. Use plenty of tape to secure the corners. The last step is to put a nylon strap overlapping the bottom, and taping it in place.  This way I have a convenient way to carry the battery when I need to. Notice that the BMS is still able to get some ventilation, and I can see the 16-LED charge indicators on the BMS.


Battery Calamity

One day while riding fast on a very rough dirt road, the metal toolbox I carry the battery in lost its lid. The battery flew over my shoulder, and landed in the dirt 15 feet ahead of me.  The battery cover protected it perfectly, and there was no harm at all to the battery. A naked battery would have been ruined. So cover em up, because stuff happens.

Battery Size

Don’t buy too small a battery for your electric bike. This type of LiFePO4 battery pack generally has a discharge rate of 2C maximum. What does that mean? If you have a battery of 10 amp hour size, a 10-amp discharge would be a 1C discharge rate. So the most you can ask of it is 2C, or 20-amps. But that does not mean your battery is going to like a 20-amp discharge. It should last longer if you back off some. So 10-15 amps is about the limit for a 10-Ah LiFePO4 of this type. 20-25 amps from a 15-Ah size, and about 30 amps from a 20-Ah size. Other types of LiFePO4, such as Headways or A123 have higher C-rates.


Now it’s time to talk about troubleshooting. Some of the procedures will simply give you peace of mind even if the battery is acting fine. It’s nice to know what voltage your battery is charging to for example.  A simple digital volt meter can be very cheap. Harbor Freight voltmeters go on sale all the time, and can even be free with a small purchase. Just having a voltmeter with you as you ride, or attached to the battery as you charge will let you know the battery actually did get charged. Or let you check the voltage if you suspect a problem. Even better, have watt and volt meter, such as a watts up or a cycle analyst installed on the bike.

But suppose you don’t have a voltmeter, and now your battery ran out earlier than usual. What do you do?  Well, go buy a voltmeter for one. You really must have something, however crude, to get started with a trouble shoot.

One thing you can do without using a voltmeter, is to take a good hard look at your charger, connectors, plugs, and fuses.  If possible, inspect the battery management system for obvious damage like something that looks burned or melted,  With some chargers, the plugs and wires are very low quality, and break easily. This pic shows that inside this charger plug, the wires are still well attached.



It should not look frayed, or have solder that doesn’t look like it melted right. Does the charger light up?  When the AC plug is connected, and it’s DC plug is connected to the battery and charging, you should see a red light.  This pic shows a common 5-amp pingbattery charger while it’s charging. LED #2 has turned amber.



The LED’s on chargers vary, some have one LED that changes color, others have two colored LED’s. But by one variation or another, it’s red light is to indicate charging, the green light means fully charged. But, here’s the catch-22, if the battery is charged, or if the battery is disconnected from the charger, the charger light turns green. So sometimes the green light means the battery is charged, and sometimes the green light means the plug is broken on the wire between the charger and the battery. This shows the pingbattery 5-amp charger unplugged, with green light that also is used to show if the battery is charged.



In this case, LED #1 stays red all the time, indicating the charger is plugged into the wall.  LED #2 changes from green to amber. So if you don’t see the green light turn red when trying to charge, look for connector problems. It could be disconnected wires where the wires are soldered to the plug, or even disconnected wires inside the charger where they solder on to the board. If the charger will not go from green to red when you plug in, look for a broken plug or wire first. Next, get your voltmeter. Here is a typical digital voltmeter set up to check pack voltage or charger voltage.



Switch on, red lead plugged into the voltage socket (in this case, that socket is marked “V” for voltage, Omega for measuring resistance, and “mA” for measuring milli-Amps. One of these three test options is selected by the main rotary switch), and the black lead is plugged into COM (meaning “common”, or ground). The main selector switch is set to DCV (meaning DC-volts), and also set it to 200V (meaning 0-200V range). When checking lower voltages (such as individual cells)set the switch to “DCV, 20V” for a more precise reading. Be very careful with the probes, and don’t short one probe to the other while checking the voltage of batteries. At 48V, it will surprise you with a big spark.

See what the voltage of the battery is. Make contacts on the plug on the battery that connects the battery to the controller. Use the red probe on the red wire, and the black wire on the black. If you can’t tell the colors, just probe with any color on each wire. When you get the red probe on the positive and the black on the negative, you will see a positive number on the voltmeter like the picture above. If it’s a negative number, simply switch the probes on the wires or plug parts (the meter will not have been damaged).

If the charger still won’t start charging the battery, check with the voltmeter to see if the charger has voltage.  Most chargers, once you plug them in, will have detectable voltage at the charger plug.



36V chargers should show 44V –46V.  48V chargers should show 58V-60V. If the charger has no voltage output, you may want to unplug it and take it apart, and just check that the wires leading into the charger are connected (from the AC main supply wires). One common failure for chargers is a resistor right where the AC connects. Look for anything that looks melted or stinks, and that would indicate that the charger failed. Cheap solder will melt at a lower temp compared to a quality solder, and sometimes a bad charger can be easily repaired.

Sometimes a battery will get discharged so low that a perfectly working charger will not start up when you plug in the battery. This might be the case if a battery is showing less than 30V for a 36V battery, or less than 40V for a 48V battery, etc. For this to have happened, it’s likely that the battery management system is malfunctioning. When the battery voltage is really low, like 0 to 10V, it often just indicates the BMS switched off. In this case, a charger will start when you plug it in, because the charger is using a different plug that is not switched off (some chargers have more than one charge-plug, so it can charge multiple packs). It can be helpful to check the battery voltage at the charging plug and the controller plug, and compare the two. A normal looking reading should be seen on the plug that the charger wants to use for charging the pack. If the charging plug also shows a much lower than normal reading, you have real trouble.

If your battery is showing that kind of low voltage, or it is simply running empty far sooner than it should, it’s time to start looking at the packs individual cell voltages. Typically, the easiest way to do this is to unplug the BMS, and use the plug (or plugs) on the battery side to read the voltage of each cell. Here is the BMS plugs on the wiring to my 48V Pingbattery BMS. It has 16 cell groups, and the wires to each cell group are in two sets of plugs.



Now, the picture shows the plugs on the battery side, after they are unplugged. You will probe with the voltmeter on these exposed copper strips, two by two.



Probing the first two contacts on the plug will give me the voltage from one cell.



3.4V–3.5V is pretty normal for a charged LiFePO4 cell. It may be higher when fresh off the charger. Now move both probes down one cell. Move both probes, but only to the next contact, not two contacts down the line. In the previous picture, the black probe will move to the contact where the red one is in the picture, and the red one moves down just one space. Repeat this till you have all your cell voltages recorded.

What you are looking for is a pattern. Is one cell way too low?  Like 0V or 1V?  There’s your problem. That’s a cell that is over-discharged and ruined. Or horrors, are all the cells reading about 1V or less?  If so…the whole battery is no good. If all the cell voltages read good, about 3.5 volts or more when fully charged, chances are the trouble is in the BMS.  Look at the BMS, and see if anything looks burnt. In this picture, the BMS has heat damage to the electronic switch on the upper left corner.

Hopefully, you just have a battery that has become unbalanced. That would be indicated by a battery that when fully charged has one or more undercharged cells. If most of the cells are normal at 3.5V, but one or two cells at are at 3.2V, that would indicate some undercharged out-of-balance cells. The undercharged cells are causing the BMS to shut off the power sooner than usual. Plug the BMS back in, and put the battery on the charger. Leave it charging for a long time, overnight for sure, but possibly for a week or more!  If the battery fails to balance, you may have to resort to charging your battery one cell at a time to restore balance.

If your battery is known to be balanced ok, but still has abnormally short range, then you are likely to have a low capacity cell, or group of cells. Batteries are often made by connecting many cells in parallel groups. Just one bad cell in one parallel group will lower the entire packs capacity. Replacing the bad cells can be a pretty advanced task, but identifying the problem may give you a basis for deciding if the battery could be repaired easily or not.

Charge the battery and balance it. Then ride the bike till the battery is nearly discharged. Checking the individual cell voltage again will show which cell groups are discharging the fastest. The lower capacity cells will have the lower voltages. Knowing how far off the voltages are from each other, and how many low capacity cells you have, can help you decide if you wish to attempt a repair. Or you might discard the whole thing if many of the cell groups show low capacity.  If you have lost 25% of your range or more, it’s just like having a battery that is too small. The remaining cells will work harder, and might be getting discharged at a C-rate that is too much for them to last for long.  So it might be best to replace a battery that has lost a lot of it’s capacity. It could still be used for a very low wattage bike perhaps, or to do something useful such as powering an emergency light source at home.

Written by DOGMAN, July 2012

Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.

  • thermal71

    Great article – Very well written and had a ton of information I can really use! Thanks a lot!

    • ElectricBIke

      Dogman is the most prolific poster on endless sphere…i am proud to have him writing here :) Thanks for the compliment i will pass it on to him.

    • trevor willis

      How did you lift it?

  • dave

    excellent i read it twice thanks…

  • Marc

    I have a protanium 24 volt battery for a Schwinn campus e-bike that needs to be replaced or rebuilt. Any suggestions on companies that might rebuild this battery?

  • Steve

    Thanks for this article. I just bought an electric scooter with a 48v LiFePo4 battery, and this is most definitely the best written article I’ve found on how to care for that battery. Cheers!

  • Ken Bell

    Thanks for a good article Dogman!

  • Frank

    I have a lifepo4 battery charger model kp-669 6 amp … when when arrived I pludded it into the battery and the light turns to yellow and fan kicks in … but after a few charges when I plug it in light stay green and hear no fan … so I got another but seem to do the same after a few charges

    • secoff

      I have the same problem with my V-Power 669 6am Battery, I have connected it and the LED 1 give me a green light and the LED 2 red….What is wrong here….

      • momac

        on some chargers like the vpower ones ,there is a switch on the back of charger that reads 110, and 220. when you plug the charger to the battery ,simply flip the switch and the amber light should come on telling you its charging, soon after when its fully charged it will turn green

  • mike

    I bought 2 Emoto Ridge 4.5 from Menards app 2 1/2 years ago, they came with panasonic lithium ion 24 volt batteriess, It wasn’t to long before one battery wouldn’t take a full charge. You article explained how the cells could become unbalanced. I checked the cells and they were different voltages. I found a 1-amp 4-volt lithium ion charger on ebay, It came from China, I cut off the plug, put alligator clips on the wires, and was able to balance the cells (7 of them 4-volt = 28-volt full chg.) Thanks for your help! Mike

  • Bob

    I have a 48v 10ah ping lifeP04 battery. I’ve had it for about 2 years and my bike quit on me one day while riding. I pedaled it home and went through all systems(checked switch and fuses all check out ok) when I checked the out put voltage it reads 13.0 volts on the main output and the charging port. When I plug in the charger it shows a red and green light indicating a full charge but none of the BMS lights come on. Is there a way to test the BMS or repair it or does it just need a new BMS or something else? Any help would be appreciated.

    • mike

      Hi ,
      Did you get an answer to your question. I had the same thing happen, but I’m getting about 24 volts out of 48.

  • boss

    i just bought a v power hk 36v 15ah ion battery w charger. hooked up the end for the bike to hook into charger… it made a poping sound when i flipped switch on battery and the light on the battery blinked on than off… no power after that. the plug is hooked up correctly, however it seems loose fitting into battery, so i was thinking it was a bad connection. i opened case to check out wires… all looked good. when i plug battery into charger the charger is red and it was amber for about 5 minutes than turned green. i plugged back into battery thinking it was fully charged. flipped switch and the same thing happened. after reading this artical, makes me believe it is the charger and not the battery at all.. i guess i need a volt meter

  • john o neill

    Thanks dogman, this is just what I was looking for. It’s so good because it cover’s so many issues I never thought about before “like the battery cover”. Great tips all round.

  • Cobbler

    Great article. Thank you. After reading this I was able to figure out that the reason why my battery suddenly started cutting out after a few minutes was probably a bad cell. Using the volt meter test on the strip plug that connects to the BSM, I found that one group of cells was at 3v, then 2.5 overnight. (The other sets were right around 4v.) Looking at the cells within that group, I found one that was corroded. After separating that one cell from the rest, I found that it had less than 1v. I plugged the pack, minus the one bad cell back in and it seems to be charging normally.
    About the battery
    24V 20AH
    14 cells in parallel x 8 sets in series.
    Usual charged voltage is close to 30V
    Made in China – Duct Tape Special from Ebay.
    4 trips of 1.25 miles each – every week day – charged at both ends – for about 6 years – about 6000 partial charge cycles – on an electric scooter, Bladez XRT 350 then Ezip 750.
    My first thought was that I should cut one cell from each parallel set to keep balance. This would take me down to something like 18.5AH and the C rating might be of a little more concern. Then I started thinking that there is no reason to cut a cell from the other sets. The one set with a cell missing is the weak link, but why weaken the rest?
    So which solution is better – cut a cell from each set for balance or just cut the one bad cell?
    Also, how do I know what kind of cell I am looking for if I want to replace the bad one? There are no markings on the blue-wrapped cell. Am I correct in calculating that each cell is about 1400 mAh – 20AH/14 cells in parallel. Is there a most common size – a little bigger than a AA? Is there any problem mixing old and new batteries?

  • Micah Wood

    My Kingpan 48V 5A charger just bit the dust. Well sort of… I got it with my 48v 15Ah ping battery. The problem is that the output voltage will not go above 54.2V. The green light is always on. Even when I plug it into my battery that needs a charge. I talked with Mr. Ping over email and he said that the output voltage is supposed to be at 59.5V. We tried raising the voltage with that potentiometer (blue box with the screw in the top) next to the fuse holder. All I am able to do is lower the output voltage with it.
    I did find a resistor that has been discolored due to too much heat but that might be a symptom of another problem. Anyone have any ideas?

    • da Bomber

      I have a ping 48×30 and had the problem of it only charging to 56 V. Ping told me sane thing with turning pathoneter (or whatever) up which did up the charge to 61V.
      After a few days the charge had gradually dropped back down again. PING then sent out a new charger under warranty

  • puckapor

    Good overview. “48v will surprise you with sparks..” yes I can confirm that :)
    Now it doesn’t charge anymore. Do BMS normally got a fuse? Can I replace BMS myself? The battery is 40ah from Hero power system. Thanks! Perra in Stockholm.

  • da Bomber

    Great article. Dogman have you rewired the 16 sense wires from the battery to the BMS yourself?? I have a PING 48vX30A pack and a couple of the fine wires that go into one of the 2 packs is loose. This results in the BMS cutting the power when the wire/s moves via vibration etc. i then plug into charge to switch CA back on and touch the loose wire to make the last couple of lights on the BMS come on. To fix this properly i will have to cut the blue shrink wrap etc and open the pack and that is why i have not fixed it as yet as im not sure what to encounter or even where to buy more shrink wrap large enough to cover pack again when fixed. Got any advice

  • cerabus

    great article. It really helped me to troubleshoot the battery i was building, a 60v 40amp battery for my ebike. its massive, but i need it to run a 1500 amp motor. I kept blowing out BMS’ every time i tried to charge it … This really helped me find out what i was doing wrong. I just plugged it in and it seems to be charging up. Cross my fingers I’m back on the road tomorrow.

  • Dave Ko

    I have a EcoReco scooter , but the LifeP04 battery is in deep discharge ( store it for too long) now is not able to charge it back … any recovery idea?