Odd Ping Battery Pack behaviour

[adamsavage79]

If we are getting numbers over 4 volts per cell then the black probe is not where it is supposed to be.

I have a full battery, and I repeated the same process and I got simlair results.The voltage is only a little different this time by a coule 1/10th of a volt, but it still "adds" as you move to the next pin. I attached a picture to show where I was putting the black probe. It also didn't seem to matter if it was directly on the circle, or simply anywhere on the flat surface.

 

[e-beach]

Sounds like it is trying to balance. Also, ping might like 56.6v. Take a look at this video at the 10:50 minute mark. Notice how he shows how to meter the balance wires at the bms. He talks about moving across the balance wire pins but he does not do it. However what you need to do (after you battery is on the charger for at least 24 hours) is do what he does, then move both probes to the right. (I say right because that is how his bms is set up. Yours might go another way.) In his case he would be measuring two white wires that are just to the right of the small black wire. That is how to test the individual cell voltages from the bms. Be sure not to short out any of the pins by touching your probes together.

[youtube]6i8i6h1LkBw[/youtube]

 

[e-beach]

On this video the poster moves the proves in the manor we are speaking about. It is hard to see, but it will give you an idea on what to do.

[youtube]6tmBEMZp6BU[/youtube]

 

[adamsavage79]

I'm going to ride it tomorrow and see if I can get the low voltage cutt off to turn on, and take a reading of the voltage it turns on at. If it's anything above 48v, that isn't normal behaviour. I'm still leaning towards a defective BMS, and the pack for the most part operates normally. From my exp, if I had a dead cell, the charger will simply not charge. It will give me a green light. The same goes with a loose wire, that connects the cells.

That being said, it doens't hurt to do this testing as I'm learning more about my battery, which is always a plus.

I'm also going to buy a new mulitmeter and see if I still get the same results.

 

[999zip999]

We were trying to just give you the stepping-stones to determine the state of charge. You are correct you are getting to the first voltage of cell one and the end voltage except 16 but it's hard for us to decide for the numbers without an abacus. But since it's Chinese we should probably use an abacus. Lol.
Okay The Signalab bms starts to balance above 3.5 volt probably set for 3.65v so 59.0 volts is fine for top voltage for the bms to bleed down the cells to balance. The bms needs a higher voltage so it can bleed down which will lower the voltage. The lifepo4 has different discharge curve then most lithium ion batteries it is very flat or where is useful voltage range exist. Meaning 3.45 or 3.5 is full if all cells are at this voltage but the BMS needs a higher voltage so it has some Headroom you're looking for where the capacity of your battery is 3.4 to 2.8v maybe a little lower but it starts falling flat and going below that will greatly greatly greatly on balance your battery do not go to lvc to trip the BMS and unbalance your battery leave something in the bottom if you drive your car to the bottom of the gas tank your pick up all the dirt in your gas tank and put it into your fuel pump and injectors..
I agree with e Beach no number should be above 4 volts there should be 16 numbers
1. 3.55v
2. 3.45v
3. 2.80v


16. Xxx v
Grasshopper
Stop running your battery to lvcc. This will grossly unbalance your battery

 

[adamsavage79]

I have no idea what "abacus" mean or "lvcc". As for each reading being over 4 volts. I dunno what else to tell you. I'm reading it correctly, and that is voltage is reading out to me. If I put my black probe anywhere else but the "B-" I get no reading at all. I even uploaded a couple pictures to show you where the black probe is going, and where the red is going.

 

[e-beach]

Lvcc was probably a type-o. And I agree that hitting lvc on a constant basis may not be the best for longevity of you pack, although a lot of evidence is now showing that going to lvc isn't what shortens the life of a battery, going to it't top end charge is what shortens the battery life. This is why your cells may be set to balance at 3.5v......Maybe.

Do you know for a fact that your BMS is set to balance at 3.5v per cell? Did you get that info from the manufacture?

Also, this is how we want you to check the cell voltages.





etc until you get all 16 3.xxv readings.

 

[adamsavage79]

I try my best to, NOT trigger the Low Voltage Shut off. I'm simply suggesting to do it this one time, to see voltage at time of the shut off. I typically do more small charges, vs less longer charges. As in, I don't let battery drain all the way, before changing. Sometimes it happens, but it was never intentional, or I needed to go, a long distance.

As for the above pictures, I will measure again doing that method. I don't know of BMS is set to balance at 3.5v.

 

[e-beach]

Ok. Going to LVC once or twice won't do anything bad to your battery unless it drains the cells lower then the manufacture specs. My LiFePO4 pack balances at 3.65 per cell. If ping set your BMS to balance at 3.5 per cell it may be a way to give a longer life to your cells.

However this is what you must do to make sure your cells are not the problem. (This is a process of elimination.)

1. Charge you battery pack for at least 24 hours.

2. Measure the voltages on your cells the way I showed you in the pictures. You should use your method for the first cell to get the first 3.XXv reading and then move sequentially along the balance wires as shown in the pictures. Be sure not to short the wires. (if your first reading is the full pack voltage, put the red prob at the other end of the connector and then start moving sequentially.)

3. Take it on a long ride to LVC. (Make sure you are close to home when this happens.)

4. Measure the cells again as described in step 2. You are now seeing if your cells discharge about the same amount, or if there is a bad cell or cell group that is discharging faster then the others.

5. Charge your pack for at least 24 hours and check the cells again.

I know this sounds like a pain, but this is how you rule out any battery cell problems.

Let us know how it goes.

 

[adamsavage79]

I finally know why the Low Voltage Cutoff is being triggered. I have a weak cell. I measured each cell one by one, and then I checked each cell, by moving the black and red probe over, one by one on the wire pins. When I reached Cell 5, I got 2.95v. When you take 2.95v and multiply it by 16, you get 47.2v. This is why the BMS thinks the battery is low. Does this mean the cell is dying, or it simply needs to be balanced ?

Also, I'm getting conflicting readings from my meter. The old one, reads 52v for the pack right now and the new one says it's 51.1.

EDIT: The Ping battery pack , fully charged and reading taken minutes after charge was complet, and still connected to charger. I got 59.4v with the new Meter, and 58.3v with old. I also tested a brand new (had been sitting for a couple years) 9 Volt Battery. I got 9.08v from new, and 8.92v from the old. I further tested on the 20v Rigid battery pack for my cordless drill. These are also fully charged, and read 20.6 from new meter, and 20.3 from old meter.

 

[e-beach]

Inexpensive meters often have differing readings. However it sounds like the new meter is more accurate.

As for the low cell, we don't know enough yet to say it is going bad or not. It is certainly out of balance. Did you leave the battery on to charge for at least 24 hours?

If not, plug it back in and let the bms do it's job and after 24 hours meter the cells again to see how balanced they are. You could even go on a short trip like 1 to 2 miles to get the other cells to discharge a little and then put it on the charger for 24 hours and see if it balances better.

If it was on the charger for 24 hours, you may have a bad cell.

Edit: Oh and btw. 16 x 3.65v = 58.4 so if your new meter is accurate, your charger is running at a higher voltage then it should.

 

[adamsavage79]

Inexpensive meters often have differing readings. However it sounds like the new meter is more accurate.

As for the low cell, we don't know enough yet to say it is going bad or not. It is certainly out of balance. Did you leave the battery on to charge for at least 24 hours?

If not, plug it back in and let the bms do it's job and after 24 hours meter the cells again to see how balanced they are. You could even go on a short trip like 1 to 2 miles to get the other cells to discharge a little and then put it on the charger for 24 hours and see if it balances better.

If it was on the charger for 24 hours, you may have a bad cell.

It's still on charger now, but I've noticed that when the battery is fully charged. All the cells, seem to the same voltage.

 

[e-beach]

Ok, so leave it on the charger over night and meter the cells in the morning and post the readings. Also plan your long run to lvc so we can meter them again to see if one battery is giving-up before the rest of them.

 

[adamsavage79]

Ok, so leave it on the charger over night and meter the cells in the morning and post the readings. Also plan your long run to lvc so we can meter them again to see if one battery is giving-up before the rest of them.

It's staying the charger. Just so we are on the same page, you want me to leave on the charger. Re check the voltage, then run to lvc again and see if the same or any cell, is giving a lower reading than the rest ?

 

[e-beach]

Leave it on the charger over night. Just because the charger looks and sounds like it is finished doesn't automatically mean that all the cells are in balance. A bms can be very slow depending on how out of balance a battery has become.

Before your ride, meter the cells like we discussed and write down the results.

Go for a long ride tomorrow. Go to lvc. Be close to home when that happens.

Once at lvc, meter the cells again to see if one or more is substantially lower then the rest. This would indicate a suspect cell (or group of cells) depending on how the battery is built. Write down the results.

Then put the battery on the charger and leave it for at least 24 hours so it can fully charge and balance.

Meter the cells again and write down the results.

That is your weekend plan.

 

[adamsavage79]

Ok I will unplug it when I get up, and then if it's not raining later Saturday, will try to get it to LVC, etc etc.

 

[e-beach]

Oh and one more thing. Make sure the bms in properly plugged in to the pack before charging.

Good Luck!

 

[fechter]

If all the cells are reaching the same voltage at the end of charge, then the balance is OK. If one is dropping faster than the others during use, then you have a bad cell.

 

[adamsavage79]

If all the cells are reaching the same voltage at the end of charge, then the balance is OK. If one is dropping faster than the others during use, then you have a bad cell.

Cell 1 is 3.60v, and the rest are 3.61v. Including the one cell that orginally showed a lower voltage than the rest. I have route planned out to ride it to LVC, that will keep me close to home as I get close to LVC. The battery was left on charger for about 15 hours. The BMS is still blinking back and forth, but I'm getting normal readings from the discharge and charge plugs. So I will let it do it's thing, and try to ride the bike later today if I can. Will depend if it rains or not.

I'm not a fan of riding in the rain, even when I'm full protected from getting wet.

 

[999zip999]

Ping will set his charger to as high as 60volt on the 2amp charger. Lifepo4 can take being charged to 3.80v . I only bulk charge to 3.50v as my target as I find this is value capacity level for daily use without bms as 20ah pack. Do you have a cycle analyst or wh/meter.
Multimeters with a weak battery can really blow your mind.

 

[adamsavage79]

Ping will set his charger to as high as 60volt on the 2amp charger. Lifepo4 can take being charged to 3.80v . I only bulk charge to 3.50v as my target as I find this is value capacity level for daily use without bms as 20ah pack. Do you have a cycle analyst or wh/meter.
Multimeters with a weak battery can really blow your mind.

Yes, the battery was very close to 60v right after the charger had finished it's charge. However, it the battery sat for 15 hours, and so the voltage slowly stablized. When I took a quick reading of the cells, before returning it to the charger overnight. I was getting 3.71v.

The Mulitmeter was bought brand new yesterday, and is using a 9v battery that is fresh. If you have a weak battery, I find that the voltage will keep climbing. That is what it did on my old Multimeter. I can't say how a newer or better one would behave with it's battery dying/weak.

 

[adamsavage79]

I ran the bike today till LVC, and ran it hard to shorten the distance needed. I got about 17 ish KM out of it, due to a headwind and a few going from a dead stop.

I did two different measurments. I did the method you guys asked me and the method Ping asked me to do. I did this with the new multimeter.

The 1st Method:

Pin 1: 3.25v
Pin 2: 3.27v
Pin 3: 3.27v
Pin 4: 3.26v
Pin 5: 2.90v
Pin 6: 3.26v
Pin 7: 3.27
Pin 8: 3.27
Pin 9: 3.27
Pin 10:3.26
Pin 11:3.26
Pin: 12: 3.26-3.27 (fluctuates)
Pin: 13: 3.27v
Pin: 14: 3.27v
Pin: 15: 3.26v
Pin: 16: 3.26v


The Ping Method:

Pin 1: 3.25v
Pin 2: 6.53 - 6.54v (fluctuates)
Pin 3: 9.81v
Pin 4: 13.09v
Pin 5: 16.03v
Pin 6: 19.30v
Pin 7: 22.5v
Pin 8: 25.8v
Pin 9: 29.1v
Pin 10: 32.3v
Pin 11: 35.6v
Pin: 12: 38.9v
Pin: 13: 42.2v
Pin: 14: 45.4v
Pin: 15: 48.7v
Pin: 16: 52.0v


Should I still leave the charger on for 24 hours, or can we conclude that cell 5 is bad ?

 

[e-beach]

Looks like cell 5 is weak. Did you meter the cells before your ride?

 

[adamsavage79]

Looks like cell 5 is weak. Did you meter the cells before your ride?

No, I forgot. But I did last night, and all the cells where equal. Seeing at the pack is 3 years old, I'm not sure if it would be a good thing to add in a new cell pack. It's voltage wont the rest, but then again nither does the weak cell and the charger is still able to charge it..

Based on the data I've collected, it would seem that if all the cells reached 2.90 then I would get LVC. It seems I could of gone 30+ km if the pack was fresh and all the cells strong. Not sure why this cell is weak, but I believe it's been like this for at least a year. Last summer is when I noticed I wasn't getting the range I normally would.

I know much more about batterys now, to know more smaller charge cycle's is better for it than less longer charge cycles. I seem to go through a pack every 3 years, based on my 1st Lithium pack and this one.

 

[e-beach]

Other people around have mentioned Ping batteries going about 3 years. I really depends on cycles compounded by age. Although smart money says to keep your full charge under the maximum manufactures charge limit, like 90% or so of full charge and it will last longer. The question becomes how to balance at that voltage.

As for your battery, since we didn't get any cell readings before you went for your ride we don't know if the 5th cell had a full charge before you rode.

Anyway, put the battery on the charger for 24 hours again and give us the reading of the voltages after a 24 hour or longer charge.

The long charging time is to make sure the bms has time to balance your cells. The bleed resistors in the bms are small and work slowly.