dead battery

Lungcookie · Apr 15, 2014

So I have been running a magic pie 3 and a Lifpo4 48v 10ah battery. (CODD Power)
6 months and 700 miles later the battery is dead.
Charge to 59v, over night 56v, 2 days 54v.
Any ideas or thoughts are welcome.
I have had the controller set to 30a/70a.
Did I over amp this battery?
Ideas for a good battery are welcome. At 30a.
Only fault is mine, just assuming I had a good high amp battery with the 6amp charger supplied with the battery...maybe not.

Batteries y26650-aa
-edit- short story I was running 30a into a 20a BMS. my fault I got amp happy.
And 1 dead cell. +4 more dead cells.

cannonball2 · Apr 15, 2014

Is the tab popped on the second cell top left front?

Kioshk · Apr 15, 2014

I'm not an eBiker, but it sure does look like what CannonBall2 says.

BTW: it's nearly the 30th Anniversary of the horrible "Cannon Ball Run 2" movie. Your screen name reminded me of it!

Lungcookie · Apr 16, 2014

yes it is. I think that happened when I pulled the tape off.
Battery was hot-glued to a paper board like stuff and duct taped up.
Guess I will re-solder and charge it up.
I have been riding off-road in the dirt and it is pretty rough riding.
I am thinking that for $300, this battery was not the best quality to begin with.
Kinda leaning towards a lipo.

snellemin · Apr 16, 2014

Lipo is your best bargain for high power setups. Just be kind to them and not deplete them below 20% capacity. They'll last you a while longer that way.

cannonball2 · Apr 16, 2014

Im not that familiar with this battery chemistry. From what I have just read it seems that nothing in either charging or discharging was improper. Seems these batteries are rated to 10C so your 70a max was reasonable. Seems max discharge V is 2.8. that would set an LVC of 44.8, not 52v as you indicate. 3.6 seems to be max charge/cell(some specs indicate 3.8) so @59v its not overly charged. If you are mistaken about the LVC then maybe the pack is good. Its actually a 51.2v battery @3.2v/cell which is exactly what you are indicating it settles to. My guess its a good pack!

Lungcookie · Apr 17, 2014

This LifPo4 battery has 48 cell, so 1.2v per cell, looks to be built in 6 banks at 7.2v.-edit- wrong
I should have giving a bit more info I guess, I could get 12+ miles out of this battery when it was new,(at 30a/70a) now it is about 7-8 miles then the BMS cuts out at 52v. (maybe a dud BMS?)

Also I soldered the loose tab, charged the battery (took about 15seconds) put the volt meter to it, started to drop immediately to 56v in about 5 min.
Now its settled to 55v. slowly dropping.(volt meter pulls a bit).
Seems like when the battery was new it did not drop voltage so fast.

I have had a CA hooked up, off and on.
The max watts put out was just over 1300w.
48v @30a=1440w
48v @70a=3360w
My thinking is setting to 30a/30a would result in the same output.
As the Magic Pie 3 will not do more than 1500w.

Has anyone cut the BMS out and just used a volt meter on these LifePo4 batteries?

I am thinking I like the sounds of a LiPo, less weight, lower price.

kevyleven007 · Apr 17, 2014

Sounds like you wore it out all right. You need a better battery. Try BMS Battery http://www.bmsbattery.com/

cannonball2 · Apr 17, 2014

I am running my Li-Ion packs with out a BMS. Probably the biggest issues is cell balancing. Charging is easy enough. The LVC in my controller cuts out with good margin and the controller limits amperage to a reasonable level, so really it simplifies battery construction. Am building a 52v pack now with 13.2ah consisting of 84 18650 cells sans a BMS. Its modular in construction so I can disconnect each 7.4v cell to charge individually for a form of balance charging.

If you are going to use R/C packs assemble them in a similar modular way so the charger will balance the cells. Even the cheap chargers will balance a 6s.

paul · Apr 17, 2014

my 48v 15ah lifepo4 does the same thing, it charges to 58.4v and drops to 56v. I contacted the company and they said that it was normal that they charge over and then they will drop a little. your bms should be cutting out around 42v. something is not right their especially since it is a 48v battery

Lungcookie said:
This LifPo4 battery has 48 cell, so 1.2v per cell, looks to be built in 6 banks at 7.2v.
I should have giving a bit more info I guess, I could get 12+ miles out of this battery when it was new,(at 30a/70a) now it is about 7-8 miles then the BMS cuts out at 52v. (maybe a dud BMS?)

That would be supper cool if it was 3.2 (like a LiPo) I would be running 153.6v!
I am sure I could hurt myself with that!

Also I soldered the loose tab, charged the battery (took about 15seconds) put the volt meter to it, started to drop immediately to 56v in about 5 min.
Now its settled to 55v. slowly dropping.(volt meter pulls a bit).
Seems like when the battery was new it did not drop voltage so fast.

I have had a CA hooked up, off and on.
The max watts put out was just over 1300w.
48v @30a=1440w
48v @70a=3360w
My thinking is setting to 30a/30a would result in the same output.
As the Magic Pie 3 will not do more than 1500w.

Has anyone cut the BMS out and just used a volt meter on these LifePo4 batteries?

I am thinking I like the sounds of a LiPo, less weight, lower price.
3x6c =57v. No BMS.

cannonball2 · Apr 17, 2014

BTW the cells have to be 3.2. The way they are series/paralleled 3p2s for a 6cell bank of 6.2v. If they were 1.2 the 6 cell bank would only be 2.4v. There appear to be 8) 6.4v cells for a total of 51.2v nominal, 57.6v fully charged. Cells like the Headway are 1.2v.

Lungcookie · Apr 17, 2014

Seems like as I read any kind of battery info it turns into the sounds that the 'Peanuts' cartoons hear when the adults talk...Whaa Whaa Whaa Wha Wha Wha Whaa.(...You know Snoopy)
No disrespect intended to any helpful peeps.
I really think I smoked the battery, due to not fully understanding all the different battery chemistry/lingo.
Amps and amp hours seem to get mixed up, 2 different things.
Was thinking others may learn from my mistake.
Make sure you know what you are buying.
This is my first ebike so it is a learning curve.
Even with all the great info on this site its hard to teach an old dog new tricks.
I will delete the BMS and see how that goes.

cannonball2 · Apr 18, 2014

That was my next suggestion to ditch the BMS. If it is cutting at 52v its gotta be faulty. Just trying to be sure you don't s**t can a good battery!

kevyleven007 · Apr 20, 2014

gotta have a bms. been there done that bad idea

Lungcookie · Apr 20, 2014

Today this battery will not even turn on the voltmeter.
Have not pulled the BMS.
Was like complete battery failure.
The thing worked great, then 1 ride the whole bike seemed like it was vibrating more than normal,(grumbly motor like). 6-7 miles later the throttle was cutting off and all the lights on the throttle would go out. Then I was pedaling 2 miles back to the house. Not that fun with out the motor I have to say.
I guess I could pull it apart and test each cell, but I don't even know what cells they are or where to get replacements.

I really just want to get some 30+amp discharge rated batts, and see if I can cook the MP3 next. I already want more power 2000w might be enough...

Lungcookie · Apr 22, 2014

More ramblings of a madman...
Spent hours over at http://batteryuniversity.com/
Thanks Paul, that sticky at the start (eBike batts & acc.) should be mandatory reading.

Started to wrap my shriveled brain around this.
Looking at BU, I would be wanting a high C rate not amp discharge.
http://batteryuniversity.com/learn/article/what_is_the_c_rate

Lifepo4 looks like its 35c so I should have been good with 30a/70a.
http://batteryuniversity.com/learn/article/lithium_based_batteries

Looks like Lifepo4 is 3.3v per cell. The way this battery is setup it is a 52v.
3cells parallel in 16 banks. (-edit-Ya your right kevyleven not 18.)

http://batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations

Pulled the BMS off and the battery is reading 50v!
So I pulled the BMS apart and it smells smoked. You know that burnt electric smell. I cant see anything burnt however.
Guess I will try a new BMS before I go and buy another battery.

kevyleven007 · Apr 22, 2014

not even close. Its 56v. 16 series 3 parallel. 35c???? nope. 2 or 3c. you cant believe everything you read buddy

cannonball2 · Apr 23, 2014

cannonball2 said:
BTW the cells have to be 3.2. The way they are series/paralleled 3p2s for a 6cell bank of 6.2v. If they were 1.2 the 6 cell bank would only be 2.4v. There appear to be 8) 6.4v cells for a total of 51.2v nominal, 57.6v fully charged. Cells like the Headway are 1.2v.

Quoting myself here rather than retype. Also correcting that Headway cells are 3.2v was thinking of super caps.

It is a 52v battery, also from what I have read the 18650(I believe that's what you have?) cells are capable of 2.8C continuous 5.6C burst. You probably exceeded the BMS capacity by having you controller set so high(70amps) and running for extended periods forcing the BMS to limit the amperage. Pretty hard on it I imagine. I would reset the controller to lower values. My Li-Ion packs are rated at 2C/cell yet the pack can provide 30amps continuous 50amp amp bursts from all the cells adding together amp wise.

You can certainly run with out a BMS with care. From what I have read recently the lifepo4 cells are the best about staying in balance. Just monitor the charge as this chemistry is critical on over voltage. If you replace the BMS DONT over amp it!
Also remember speed, if that is what you are after comes from voltage, amperage adds torque.

Lungcookie · Apr 23, 2014

cannonball2 said:
Quoting myself here rather than retype. Also correcting that Headway cells are 3.2v was thinking of super caps.

It is a 52v battery, also from what I have read the 18650(I believe that's what you have?) cells are capable of 2.8C continuous 5.6C burst. You probably exceeded the BMS capacity by having you controller set so high(70amps) and running for extended periods forcing the BMS to limit the amperage. Pretty hard on it I imagine. I would reset the controller to lower values. My Li-Ion packs are rated at 2C/cell yet the pack can provide 30amps continuous 50amp amp bursts from all the cells adding together amp wise.

You can certainly run with out a BMS with care. From what I have read recently the lifepo4 cells are the best about staying in balance. Just monitor the charge as this chemistry is critical on over voltage. If you replace the BMS DONT over amp it!
Also remember speed, if that is what you are after comes from voltage, amperage adds torque.

That was my initial impression.
Normally when riding on road as you take off it uses peak amps/watts then drops lower when you get to speed. Using a Cycle Analyst I get a bit over 1300watts at get go, then as I am cruising down the road I only run around 500w or less.

The last 200 miles I have been riding off-road mostly in soft dirt/ high desert sand.
As such I am on the gas a lot more/ longer. Didn't have the CA hooked up in the dirt so I don't know what kinda juice I was pulling.

In my defense I stated 35c because that's what it says at 'Battery University'.
In that chart I linked above.

I am just glad the battery is still alive...now on to the BMS!

kevyleven007 · Apr 23, 2014

Batteries y26650-aa cells( standard LiFiPO4) not 18650(NCM Li-ion) Not the same size… the 26 refers to the diameter in mm. (Same length, though.) . Should fully charge to 58 to 56 volts if charging at 60v. Some say charge at 3.55v per cell. Nominal voltage should be 52.8volts. some say a little higher some a little lower depends on the cells and bms. You were suckin waaay to much amps for that little battery you need at LEAST 20 ah 30 would be better for those cells to last. and also what is the bms set for? That should be the final deciding factor. LiFePO4 packs are really only good for about 1 to 3c most of the time. I know codd power says they are 10c cells but so far all I hear is bad things about them. And you are not proving them wrong. That little pack is probably only good for about 15 amps cont. discharge. Don't try charging it without a bms unless you lower the voltage of the charger. look it up on utube. Good luck man!

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