kit of 16 batteries 40152 LiFePO4 Battery Cell 3.2V 15AH

[Abe]

Hello Alen,

Recently I bought a kit of 16 batteries 40152 LiFePO4 Battery Cell 3.2V 15AH.
I assembled the kit as directed and carefully, of course, I conducted a series of integrity checks and everything seems reasonable (including the BMS, of course).
When I connected the battery with BMS to the motor,the motor did not work, but when I connected the battery without BMS directly to the motor everything worked.
There is a way I can check the health of the controller BMS?

* Indicator of battery charge, all three lights were lit., green, yellow together, why?

What do you think?

Thank you,
Abe

[Bikemad]

Hi Abe,

It would appear that the BMS is not allowing the power to reach the motor.
Are you sure the BMS is programmed correctly for 3.2V LiFePO₄ cells not 3.7V LiMn, LiPo etc.?

Also make sure that none of the balance wires have been accidentally mixed up. Use a voltmeter on the balance lead connector plug to check for correctly incrementing voltage on each of the pins from the Negative to Positive end.

Double check all the cell voltages to ensure they are within the expected range (2.8V - 3.65V) and are all connected correctly (check that none of the cells have been accidentally fitted or wired in reverse )

Make sure that the leads for the Battery, Charger and Power Output connections are correct.

If everything is connected properly and the cell voltages are all OK, then it is likely to be either a faulty or incorrect BMS unit.

Alan
 

[Abe]

Hi Alan,
I checked mentioned in on your recommendation, everything looks fine.
If so, can you recommend a BMS controller I need:
I have 16S cells Lifepo4 in each of 3.2V 15AH, ie total 48V.
New motor 1000W Magic Pie 4
Thanks,
Abe
** I'm posting two links, which of the two is recommended?
http://www.aliexpress.com/store/product/48V-1400W-LiFePO4-Battery-BMS-PCB-16S-58-4V-Electric-Bicycle-Battery-BMS-30A-continuous-60A/1807188_32376590032.html
http://www.aliexpress.com/store/product/48V-2500W-LiFePO4-Battery-BMS-PCB-16S-58-4V-Electric-Bicycle-Battery-BMS-60A-continuous-120A/1807188_32381228548.html

[Bikemad]

I found this one on bmsbattery.com and it is $20.60 for the 16S version.
30 Amps continuous should be more than enough for the MP4, but I don't know whether it comes with the two 8 pin balance connectors and leads:


This BMS should be ideal for your battery.
Click the image for more details.


Alan
 

[Abe]

Hi Alan,
First of all thank you, I apologize in advance, but, I ask for your help to test the parameters of the two links below and tell me if they are also suitable for:

** I'm posting two links, which of the two is recommended?
http://www.aliexpress.com/store/product/48V-1400W-LiFePO4-Battery-BMS-PCB-16S-58-4V-Electric-Bicycle-Battery-BMS-30A-continuous-60A/1807188_32376590032.html
http://www.aliexpress.com/store/product/48V-2500W-LiFePO4-Battery-BMS-PCB-16S-58-4V-Electric-Bicycle-Battery-BMS-60A-continuous-120A/1807188_32381228548.html
Thanks,
Abe

[Bikemad]

Hi Abe,

Either of those should be OK for your battery and as I said before, the 30 Amps continuous will be more than enough for the MP4.

However, if you are likely to upgrade to a dual Pie or use the battery pack to power a more powerful motor in the future, it might be better to go for the 60 Amps continuous version. (Just make sure that you use suitable gauge wiring between the cells and the BMS etc.)

If you are using 15Ah Headway cells (or similar clones) they should be good for 5C continuous (75 Amps) and  10C max (150 Amps) so they should not be overloaded at the peak 120 Amps that the BMS allows.

Alan
   

[Abe]

Hello Alan,
Thank you very much, with your help, I found the problem, now everything works great.

**Why all the lights are lit along the top of the Throttle (thumb throttle), which should indicate the status of the battery?
Thanks,
Ave

[Bikemad]

* Indicator of battery charge, all three lights were lit., green, yellow together, why?

All three lights should be on when the battery is full, and they gradually go out (one at a time) as the voltage drops.
When the last Red LED is the only one lit, it means the battery is almost completely empty.

Unfortunately, the simple LED battery gauge was originally designed for use with lead acid batteries, so it was never very good with the newer lithium batteries. Check out this post for more details.

Alan
 
P.S. What was causing the problem?

[Abe]

Hello Alan,
Unfortunately it's a long story, I'll be brief (I'm not sure if the following explanation makes sense).
The operating is done through "key" + relays of 80 amps each.
When the system was not working I hooked up the circuit the positive side of the battery, after extensive testing have not found any connection error so I got in touch with you.
After thinking (with no explanation reasonable utilization) composed the "key" + relays negative side of the controller BMS time (-P Load) and everything started working.
** You have an explanation?

Abe

[Aliasssss]

Hello guys.

Abe I also use 16 pieces of Headway 40152S LiFePO4 cells in series for my 48v(54.6v) pack.

I don't use a BMS (and I don't encourage anyone to use one) because I strongly believe, based on mine and others experiences, that the BMS will do more WRONG than GOOD.

In time and as they cycles go by, that BMS will eat up one of your cells, the one with the smallest capacity. Instead bottom balance all cells to 2.75v before making the pack and I can assure you that in normal use after about 300 cycles the cells are still balanced to about 0.03v when discharging them full ( a full cycle) to 2.9v each, that's 46.4v per pack. I have to mention that I dropped a cell onto a cement floor and it had a small indentation and sure enough after about 40 more cycles it died, so be careful not to drop the cells. Each year, right before the start of the spring I do a full charge and discharge ( a full cycle) to bottom balance of the cells, hence the few full cycles. 

Anyway I'm completely proud of choosing the Headway 40152S 3.2v 15Ah LiFePO4 cells as while doing a controlled full discharge I can still draw 14960mAh of capacity after 300 cycles ( of about 35% Depth of Discharge each, with only 4 or 5 full 15000mAh discharges) and 3 full years of daily usage(well for at least 8 months a year).

The degeneration of cells is about 2.8% in 3 years and 300 cycles and that is according to the manufacturer specs. If the degeneration is linear after about 1200 cycles more it would be around 15%, that is way under the 20% specified, which is very good, but I guess we'll see as the years go by to which extent the degeneration is affected by the aging of the cells.

Cheers.

PS - Take good care of your cells and they will serve you good for many years and hundreds hopefully thousands of cycles.