how to PRE charge test capacity headway cells and which BMS and Smart CHARGER afterward?

[sharinginfos]

hi Endless sphere

Ineed your help knowledge:

I Have a xiongda 2 speed motor 48volt high torque 350w rear. 15 amps max
the controller is a kt48svprc xd15d ,
rated current 7A;
max current:15A +-1A it looks similar to this one in the very bottom link.

I am exploring the possibility of building a battery with 16s 1p used cells from batteryhookup to go up hill not very long distance

:
They say on their site USED HEADWAY 38120 HP 3.2V 8AH LIFEPO4 BATTERY 5 dollars.
THESE CELLS HAVE ALL BEEN VOLTAGE TESTED AND INSPECTED TO BE IN PERFECT WORKING CONDITION AND HAVE ALL BEEN REMOVED FROM WORKING MODULES. WE HAVE TESTED HUNDREDS OF THOUSANDS OF CELLS OUT OF THESE MODULES AND WE HAVE BEEN AVERAGING AROUND 95% CAPACITY. WE GUARANTEE NO DEAD CELLS

So they say averaging 95 pourcent capacity

PREBUILD
============================
how many of those cells should i buy to be sure I have good capacity cells ? 18 19? and dismissing the lower capacity ones?(only 5 dollars each !)

How exactly can i mesure the capacity in them and is it necessary ? with what tool?
is testing for the internal resistance a necessity ?

++++++++++++++++++++++++
once that is done , i will probably need a good bms and stuff for safety precautions, what BMS do you suggests me ?what are my choices ?
NOTE that the bike could possibly eventually host an additionnal second 15A motor eventually for front wheel or just a pure replacement of xiongda for a stronger motor if xiongda does not do the job in hills. so i dont know if there would be a down side to have a Bms for higher amps than what the xionda and controler would ask at fist(15amp.)

Do i need a LVD?

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CHARGER I do wish to have a smart charger that give current smartly so that it is would still be safe to keep the charger plugged if i forget to unplug it for a day or 2. If possible i would like also to be able to select charge at 80 90 or 100 pourcent capacityand to select the current charging them . i wont buy a satiator. which chargher would fit those wish a fit hte bms that would serve me right?.

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I wonder if there is top balancing or bottom balancing needed.
any other gadjet would be useful ? i m a noob so tell me what i dont see or should be aware , im open.

thanks


https://www.aliexpress.com/item/3282132 ... IQaT6Ecexa

 

[lnanek]

There's lots of chargers out there like the LiitoKala that will discharge a cell, charge the cell, then report the capacity to you. Lots of cell voltage meters will report internal resistance too. I have a Tenergy 5-in-1 Battery Meter that reports it for 6 cells at a time even.

 

[sharinginfos]

Hi
For the capacity test,
i have a bt c3100. can this charge headway lifepo4 cell? with or without aligator wire? cause im not sure if headway cell fit in.
if what is the name of a machine that will do it like model names? (not expensive cause it might be the only battery i build)


about internal resistance is it really necessary to test it since i ll do a 16s 1p ?

thanks

 

[sharinginfos]

no one?

 

[v85]

1-how many of those cells should i buy to be sure I have good capacity cells ? 18 19? and dismissing the lower capacity ones?(only 5 dollars each !)

2-How exactly can i mesure the capacity in them and is it necessary ? with what tool?
3-is testing for the internal resistance a necessity ?

++++++++++++++++++++++++
4-once that is done , i will probably need a good bms and stuff for safety precautions, what BMS do you suggests me ?what are my choices ?

Do i need a LVD?

---------------------
5-CHARGER I do wish to have a smart charger that give current smartly so that it is would still be safe to keep the charger plugged if i forget to unplug it for a day or 2. If possible i would like also to be able to select charge at 80 90 or 100 pourcent capacityand to select the current charging them . i wont buy a satiator. which chargher would fit those wish a fit hte bms that would serve me right?

6-I wonder if there is top balancing or bottom balancing needed.
any other gadjet would be useful ?

1-Probably cells they offer are equally used, but no guarantee. So if you buy 16 cells then you can order more if needed.
2-For capacity measurement there are some discharge meters with display (150W-180W) on aliexpress, but IMO is not needed.
3-With internal resistance measurement you can recognize bad cells with higher resistance than in specification
4-For BMS i choose one with Bluetooth support (LLT, but JKBMS with active balancing probably is better) to monitor cells voltages (and because i`m curious)
You can use lower current limit BMS for charging/balancing only with high current discharge cells, but i choose one that cover my needs and to have ability to monitor discharge too
BMS common port vs seperate port
5-Smart charger IMO are not very popular (Cycle Satiator looks like is very nice device, but price is not for my wallet). I choose adjustable charger
6-With Bluetooth BMS you can monitor cell balancing
There are interesting videos about that topic on Off-Grid Garage channel:
https://youtu.be/qZg4Jxftw-c
https://youtu.be/86J7gJ9-r_8
https://youtu.be/wUvfzDuRVtE
It looks like top balancing is necessary and with big difference in voltage between cells, top balancing to be on stages 3.4V single cells and then 3.5V for all parallel connected
Video on Will Prowse channel: https://youtu.be/x5ABvbbics8
Recommended Charge Profile for DIY LiFePO4 Batteries
(Why you cannot charge LiFePO4 below 0 degrees Celsius)

i have a bt c3100. can this charge headway lifepo4 cell? with or without aligator wire? cause im not sure if headway cell fit in.

Yes, you can use Opus for charging/discharging LiFePO4:
https://secondlifestorage.com/index.php?threads/opus-bt-c3100-v2-2-review-and-discussion.1997/
You need two wires and aa or any other empty cell adapter that fit charger slot. Here photos with 33140:

https://ae01.alicdn.com/kf/A0d0c88968f664d61a49f064d5b0cfbd8J.jpg
https://ae01.alicdn.com/kf/A79fb036d31454345b375a83c88055360y.jpg

 

[sharinginfos]

hi thx for you generous answer, ill have to look at them one point at the time .
for starter are you saying that with opus 3100 and empty cell trick i can calculate the capacity of the headway cells?
and is that necessary since i will do 16s 1p?

for internal resistance i remember having seen a tool not that expenssive but forgot the model no . would you know a good tool for that? since i need 16 cell do you think it is a good strategy to buy 18 test for the IR and select the 16 best out of the 18?

 

[Hummina Shadeeba]

With lifepo4 I feel safe just using the light up “discharge balancers”. Cheap and small

Theres simple cheap capacity testers u can find. Finding the internal resistance isn’t necessary if u know the capacity but there’s the “three wire method” for finding precise resistance of a cell. Even then it’s hard and the connections make a big difference. I’ve had the tool for finding the internal resistance and I returned it as it was too fickle with the connections