Ping BMS: One LED never comes on while charging (SOLVED)

[BlackburnPete]

I have a new Ping battery (48V 20Ah) and when I charge the pack (5A charger) , eventually one LED on the BMS will blink a few times and then come on solid. Next, the rest of the LEDs will twinkle and then light up solid within a minute or two. All the LEDS are solid except for one and then the charger light goes green and the charger goes silent. I left the charger on with the green light for another hour but the last LED never lit up. After I disconnected the charger from the pack and unplugged it from the wall, all the lights (except the one that never lit up) continue to stay lit and eventually, one by one, they blink and then go out. The pack is resting at 58.0V.
Do I need to be concerned about that one LED that never lights up?

[The last LED lit up on the third charge after I left the pack on charge overnight even though the green light was already on before I went to bed. Thanks for the help.]

 

[dnmun]

is your ping charger putting out 60V? the cell may be balanced and the led bad. not to worry, it may come on eventually

 

[Russell]

Do I need to be concerned about that one LED that never lights up?

A little bit because it means the voltage for that cell never got high enough to activate the shunt circuit. If you have a DVM you could check the cell voltage manually and compare it to the others. With the pack at 58.0V it's probably close and will likely come up after a few cycles but keep an eye on it.

-R

 

[BlackburnPete]

Thanks for the advice. I will keep an eye on this cell for the next few cycles. I was going to check the output of the charger with my multi-tester when common sense took over and I realized my chances of shorting out the XLR connector was more likely than actually getting a reading. What happens to the charger to make it switch from 2 red lights to one red and one green? I have the 5A Aluminum case charger.

 

[Russell]

I bought one of those same chargers from another vendor and I specified I wanted the LED indicator to go green at 0.2A, which it does. What your charger is set for I couldn't say but no matter though because it doesn't mean much. The voltage on this charger stays high therefore current will continue to flow into the battery until the voltages equalize. That's also why it's a good idea to do as you have done and leave the charger connected for an hour after the LED turns green, especially when the battery is new. I like to see exactly what is going on so I terminate everything with Anderson Powerpoles so that I can insert a Watts-Up meter to monitor the charging process.



Having the LED indicators on the BMS is nice because it does give you a quick visual indicator of what's happening and that's fine too if everything works perfectly however there's nothing like checking voltages manually to get the whole picture.


-R

 

[BLUESTREAK]

I don't think you have anything to worry about, ping say's that this may happen when first useing the battery but after a few cycles it will come on.

 

[dogman dan]

Like my new ping when right out of the box, a few led's may not light up the first few cycles. I did short discharges and put it back on the charger, leaving on an extra hour about 3 times, and then put it to bed on charge overnight. By the time I went to bed, all the lights were lighting, but 3 of them took a lot longer.

Now they all light up close to the same time, and as surface charge bleeds down, go out about the same time.

It's just the" break in", which is the wrong word to use, but one everybody can understand. Actually the cells just need a bit more balancing that they have when factory fresh. Generally 10 cycles or less takes care of it. Always best to leave the battery on the charger at leas a little while after the light turns green.

Some advise charging to a slightly lower voltage for pack lifespan. My way to do this is to use a cheap sla charger often, which only goes to 58v, instead of the ping that goes to 60.5.

 

[BlackburnPete]

Thanks again. Now I am looking forward to getting out on a few more rides and putting some shallow cycles on the battery. My first run was 9 Ah (40 km) and I would like to put about 10 more shallow cycles on the pack. After I am done with this "breaking-in" period, how far down do you guys run your ping batteries. I have heard people say that they take them right down until the LVC shuts them down because the BMS has the proper settings to prevent any damage. Others recommend not going past 80% (16Ah) to make sure the pack lasts for the maximum number of cycles.

By the way, Ping did an awesome job on packaging the parcel for delivery. He used lots of tape and Styrofoam to keep everything safe. The delivery time was less than 2 weeks from the day I placed the order until it showed up at my door. I am very impressed with Ping's commitment to customer service.

 

[dnmun]

do not count on the BMS to protect you at low voltage. i have seen both BMSs allow individual cells to drop below the 2V level without shutting down. so avoid exhausting the battery to that level if possible.

 

[snowranger]

I thought you said that this was a good bms design. What changed your mind?

 

[dnmun]

i had the experience of watching a cell drop below 2V, and no shutoff, still think it is a good design, since it will shut off the charge but don't understand why these did not turn it off at LVC. but i have seen other BMSs also fail to shut off discharge in the same situation.

 

[dogman dan]

He's right, but on the other hand, I've taken my ping v1 bms down to cutoff, waited a few miniutes, and then plugged it back in to ride at very low watts to reduce cogging to get home at least half a dozen times. and dozens of times I've simply rode till it cutoff for one good reason or other. For a good reason, not just to avoid charging sooner.

I can't say you will be fine if you do it, but so far I have. I don't ride my pack any lower than I have a reason to, so if I can charge, I do, even if it's only had 1 ah taken out. But I also don't start pedaling that heavy bike unpowered because a meter says I have 80% discharged. To me that would be silly. I did, however, buy a battery the right size to only need 75% to get home on most days. But with a headwind, I've hit the cutoff in the driveway of my house many many times.

Why does this work for me and maybe not for others? Simple, I think it's from keeping the c rate low if possible. Largish battery and smallish controller.

The way I use my battery tends to keep it well balanced, so all the cells reach lvc at the same time. A runt cell in the pack, is not the bms's fault. But it is a fault in the bms if it can't save a runt cell.

 

[Russell]

Thanks again. Now I am looking forward to getting out on a few more rides and putting some shallow cycles on the battery. My first run was 9 Ah (40 km) and I would like to put about 10 more shallow cycles on the pack. After I am done with this "breaking-in" period, how far down do you guys run your ping batteries. I have heard people say that they take them right down until the LVC shuts them down because the BMS has the proper settings to prevent any damage. Others recommend not going past 80% (16Ah) to make sure the pack lasts for the maximum number of cycles.

I try to keep my use to less than 80% DOD and the most I've used is 93% of the theorectical capacity (I've never taken it to 100% so I can't say where that is). At 80% the voltage sag under load does start to increase significantly and the motor feels noticeably less peppy.

Here are discharge curves for a Fusin battery however they closely depict what you can expect from a Ping.



When my 10Ah battery is at 80% DOD the voltage will hit ~2.85V/cell with a 20A load similar to what the curves above show.

For a long time I had a Watt's up meter in front of me however a few months ago I moved it to the trunk bag with the battery. I still wanted some kind of voltage display and I wanted a light too so I bought one of these combo units off of eBay.



The display has 4 blue LED's which I found illuminate at around 43,45,47 and 49V plus a red LED on the far left. The LED's are actually quite useful and I use the red LED as a last warning like the "low gas" light in a car.

-R

 

[dogman dan]

I've had the same setup on fusin kits. It doesn't work so good as a voltmeter with lifepo4, since as soon as you stop, all the led's light back up. But it works great as a voltage sag indicator while riding. So if you want to baby the pack as it approaches cutout, you can start riding in a way than keeps as many as possible of the led's lit. A simple intuitive guide to riding more efficient, at a lot less cost than a cyclelanalyst. I could very very accurately predict cutoff after a few hundred miles with on of those led meters.

 

[BlackburnPete]

Thanks for all of your help and experience. The last stubborn LED finally lit up when I left the charger on overnight. I got an email from Ping who told me that the green light on the charger basically means that the charger is not doing anything, but that it will come back on later and that the light will go from green back to red and finish charging the last stubborn cell.

I am very pleased with Ping's excellent customer service. Tell your friends!

 

[Russell]

Thanks for all of your help and experience. The last stubborn LED finally lit up when I left the charger on overnight. I got an email from Ping who told me that the green light on the charger basically means that the charger is not doing anything, but that it will come back on later and that the light will go from green back to red and finish charging the last stubborn cell.

I am very pleased with Ping's excellent customer service. Tell your friends!

I beg to differ with Mr Ping but when the green LED is on the charger IS doing something as long as the BMS hasn't cut it off. The green LED comes on for TWO reasons, either the current has reached the internal setpoint or the battery is not connected. When the current reaches the internal setpoint the voltage stays high (true for many chargers including the optional KingPower supplied by Ping) and there is still current flowing as long as the battery voltage is below the charger voltage. The trickle of current can bring up a low cell but it takes time. The best way to know if this is the case is to have a wattmeter or ammeter in-line or you can monitor the battery voltage and see it slooooooooowly inch a few hundreths of a volt higher. The other thing which can cause the LED to go green when it is still connected to the battery is if one cell goes too high and trips the BMS overcharge detect circuit which then opens the charging circuit and without a connection the LED goes green. After the BMS shunt circuit drains the high cell the BMS fault is removed and the BMS allows current flow again. Therefore if your charger LED turns green then cycles once in a while to red it likely means the BMS has interrupted the current flow.

-R

 

[John500]

I was trying to summarize this thread for my notes. I see the various points made of faulty charger, faulty BMS, low cell, lazy cell, bad cell. In the end, the solution appears to be to do nothing. There was no fault. (Note to self, forget this post)
After the first use of my 20 LiFePO's (no BMS), I dutifully got out my VM and found one cell at 0.20V below the average of 3.45V. Panic, bad cell, find a source for a new one! While looking for a source, I stumbled across a fellow, who has been described here as a "loud mouth, arrogant, and even stupid know-nothing" and his advice was to relax and wait for 10+ charge/discharge cycles. I also saw the same advice from Mountain Chen, the original supplier of my scoot. With nothing to loose, I followed the advice. Now, I find the pack is very well balanced as at any state of discharge, all cells are withing 0.02V. After a full charge, and an hours rest, they are all at 3.85V. Would all the LED's on a BMS tell me more?
My one question is, why do so many people concentrate on only the fully charged voltage? Isn't it more important to check the cells after a partial or full discharge than immediately after a full charge? Don't you learn more about your pack's true condition when it is discharged, than fully charged? When you get to 2.5V average and find one at 2.2V, don't you know more than immediately after charging them and finding them all close to 3.95V?
Making a science project out of going for a ride may satisfy the needs of some, but in this thread, I think I sense the same unnecessary worry I experienced after my first ride?

 

[BlackburnPete]

John, I am glad to hear that cycling the pack through a few charge/discharge cycles solved your problems too. I find the discussions and advice on this forum help me a lot. Even though this is not my first battery or even my first LiFePO4 pack, I still found the information in this topic relevant, especially when it comes from people who have experience with Mr. Ping's batteries and BMS/Charger characteristics. I hope it helps calm the nerves of other Ping newbies.
John, How does your scooter work with your LiFePO4 pack? How many amps does your scooter draw? My daughter has a scooter with a 48V SLA battery pack and I was wondering if one of my 48V 20Ah packs would be suitable for the scooter.

 

[dogman dan]

Interesting comments guys. Green light on the charger means two things,

One- battery is fully charged, and a tiny trickle of power is still flowing to the battery. A low cell will balance if left plugged in long enough, a I did when charging with a too low voltage charger for my ping v1.

Two, the battery is disconnected from the charger. It could be unplugged , it could be the bms is working and shut down charging to discharge high cells, it could have a broken connector or wire and never charged any, it could have an intermittent bad connection and charged a little bit.

Great little led's, They tell you for sure that everything is hunky dory, or you are screwed. No telling which. Only a wattmeter or voltmeter will tell you if the dang thing charged at all. Some genius must have thought up this setup.

 

[Russell]

I was trying to summarize this thread for my notes. I see the various points made of faulty charger, faulty BMS, low cell, lazy cell, bad cell. In the end, the solution appears to be to do nothing. There was no fault. (Note to self, forget this post)After the first use of my 20 LiFePO's (no BMS), I dutifully got out my VM and found one cell at 0.20V below the average of 3.45V. Panic, bad cell, find a source for a new one! While looking for a source, I stumbled across a fellow, who has been described here as a "loud mouth, arrogant, and even stupid know-nothing" and his advice was to relax and wait for 10+ charge/discharge cycles. I also saw the same advice from Mountain Chen, the original supplier of my scoot. With nothing to loose, I followed the advice. Now, I find the pack is very well balanced as at any state of discharge, all cells are withing 0.02V. After a full charge, and an hours rest, they are all at 3.85V. Would all the LED's on a BMS tell me more?
My one question is, why do so many people concentrate on only the fully charged voltage? Isn't it more important to check the cells after a partial or full discharge than immediately after a full charge? Don't you learn more about your pack's true condition when it is discharged, than fully charged? When you get to 2.5V average and find one at 2.2V, don't you know more than immediately after charging them and finding them all close to 3.95V?
Making a science project out of going for a ride may satisfy the needs of some, but in this thread, I think I sense the same unnecessary worry I experienced after my first ride?

Not to nit-pick but this is what folks REALLY said;

The first respondent (dnmum) ended by saying “…not to worry, it may come on eventually”

The second respondent (me) ended by saying “…it's probably close and will likely come up after a few cycles...”

The third respondent (Bluestreak) said “…after a few cycles it will come on”

The forth respondent said…well you get the picture, nobody was saying anything was broken or it was a situation to get alarmed about.

I find the more you know about how your components work, and I don't mean hearsay, but how they REALLY work then you'll tend to worry less. A DVM and a wattmeter go a long way to help you understand what your charger, BMS and battery are doing. People relate to your problem based on their own experiences, some are relevant to your situation, some aren't so much but all try to help so to say you're going to "forget this post" is insulting to all of us.

-R

 

[John500]

Sorry for the bad choice of words. The note was to "myself" and I was not suggesting the post was without merit. It is just one I don't need to file for reference. The thought I was trying to convey is to relax and enjoy, not to worry too much on a new battery. I'm happy not to have a BMS to worry me to death. Perhaps time will tell if this is a huge mistake. If needed, I can purchase a few cells with the money saved. I don't run around in my cages with my OBDIII reader plugged in and I won't be riding around with an overload of information presented to me on my bike. Least I get distracted and crash.
Cheers!

 

[John500]

John, I am glad to hear that cycling the pack through a few charge/discharge cycles solved your problems too. I find the discussions and advice on this forum help me a lot. Even though this is not my first battery or even my first LiFePO4 pack, I still found the information in this topic relevant, especially when it comes from people who have experience with Mr. Ping's batteries and BMS/Charger characteristics. I hope it helps calm the nerves of other Ping newbies.
John, How does your scooter work with your LiFePO4 pack? How many amps does your scooter draw? My daughter has a scooter with a 48V SLA battery pack and I was wondering if one of my 48V 20Ah packs would be suitable for the scooter.

Pete;
It would be great if My. Ping included Bob Marley's "Don't worry, be happy" or wait a few cycles before you worry about the leetle lites.
On my 3rd or 4th charge, I found 2 flashing red lights when I went out in the morning. I had already learned to not suspect the worst, so I unplugged the charger from the scoot, then from the supply. When I plugged it back in, I still had 2 flashing red lights. Unplugged again, turned on the key and ran the motor, while on the center stand, for a few minutes. I plugged in the charger and , perfect. I went 30Km, got out the DVM and all was well. Maybe the 2hp vacuum cleaner, on the same circuit, shot a spike, maybe the 250 amp welder on the mains, who knows? I'm not dragging out the Tektronix Dual Channel until the smoke gets out and I really have to figure things out. Save the brain for enjoying the pleasures of life.

I have never calculated or measured the draw. My TS battery is 60V @ 40Ah. As you are in the land of Celsius; I comfortable go 60Km at 60Kmph, with many hills on the trip. I often go 80Kph+ for the last 5Km+. WOT gives me 55-60Kph on the last 2 hills to home, after the 60Km trip. Either my speedo error is growing or Mountain Chen's advice that the pack will get stronger after you exercise it a few times was correct. Top speed has increased 3kmph after a few charge cycles.

The first two scoots I tried were 500W 48V 12 Ah and 500W+ 20Ah SLA. Great fun on the flat, but totally useless on a modest hill. One of the fellows installed a 20Ah LIPO in place of the 20Ah SLA and it is a totally different machine. The range is almost double and the discharge curve is so relatively flat, there is no comparison. It appears a 20Ah LiPO is equal to a 40Ah SLA. When you consider the weight saving, it probably is. At my 100kg's, I envy the 50kg daughters who blast around using minimal power on their scoots. I look forward to soon riding a 30kg machine instead one that is 150kg. Once I get the brakes sorted out, I'll decide how fast to make it go.

 

[dnmun]

the final shunt current on that v2.5 signalab BMS is about 70mA. if there is more current than that going through your ammeter during charging it is being stored in the pack.

 

[John500]

the final shunt current on that v2.5 signalab BMS is about 70mA. if there is more current than that going through your ammeter during charging it is being stored in the pack.

Is this 70mA per cell or total current?

I have found 3 cells .3V low so I am balancing the pack right now.

Thanks;
John

 

[dnmun]

70mA going out of the charger, all leds lit, no current is going into the cells at this point, all the current is shunted around the cell for all cells, but if there is more current flowing out of the charger, then that means there is some current not shunted around the cell so that current is accumulating charge in the cell. ie stored charge.