Hello Everyone,
I originally made this post on the diyelectriccar forum, but the guys there suggested me that this forum has more knowledgeble users for what relates to my question, so im pasting the same here.
I'd like to start by thanking anyone with enough patience to read it all, i have a degree in electronics but my daily job is in a completely different field so,
with my knowledge aging and rotting away, i want to double check with you experts to make sure i don't do any dumb mistake.
I recently had the luck to acquire a batch of still sealed laptop batteries from a closing office.
These were in a spare-parts stock and have 0 cycles on them as they were never used.
I opened all the batteries and harvested the cells, then used my D2 Digicharger to charge them all, plus estimate the capacity by measuring how much time they took to charge (the D2 uses constant 500mA for charging).
I have in total 232 Cells, but they are of different capacities.
I split them in 2 batches:
130 Cells (labeled Old Batch) are those i harvested almost exactly a year ago and after fully charging them i put them aside waiting to get more (measured most of them today, after a year of storage they dropped to 4.10-4.16V so they look healthy).
102 Cells (labeled New Batch) i harvested and charged in the last 2 weeks.
My objective is to convert my bike to kinda-hybrid, it has quick-release front tire, so i wish to buy a front wheel hub motor that i can connect and disconnect quickly in order to "choose in the morning" if for the day i need it electric or pedal-only.
The motor controller will be connected via Ubolts and the battery will be on the package carrier secured with bolts and straps.
I was thinking of using one of these motors.
Currently i usually cycle 50-70 km on pedals, i wish to achieve a similar (or more if possible) range with electric (so with minimum pedaling), but my main doubt is whether or not 36V is enough to overcome steep-ish hills or if i should get a 48V motor instead.
I attached a PDF/Excel of all the cells i have, if they were all the same i wouldn't have any problem, but they are different capacity/C-Rate, so i'm not sure how to proceed.
If i am to combine only the NCR18650 i have (they are the cells i have most of with 99 identical ones), i can do a 13S7P using 91 Cells, that would give me a 48V 19.60Ah (917Wh cca.) pack and im not sure these numbers are sufficient for the range i wish to achieve.
If instead i am to combine different cells, what would be the best way to do it?
First thought goes torward combining them in the parallels, so to have multiple parallels of same capacity that will self balance and then series them (so for example 7P of NCR and an additional 2 UR18650FM that are similar specs so to have a 13S9P or more), or more advancedly as rePackr - 18650 pack builder shows.
Could you please advise if it is a sound thought?
Considering i would like to have as many stats as possible, could you advise on a good BMS with sensors?
I also plan to have multiple temperature sensors inside the battery in various spots and have an ESP8266 send them to my main screen so i can keep an eye on the temperatures at all times.
Please feel free to tell me i'm an idiot or such, i wish as much input as possible to understand what can be done better, starting with motor, controller, battery plans etc.
Thanks to everyone in advance.
I originally made this post on the diyelectriccar forum, but the guys there suggested me that this forum has more knowledgeble users for what relates to my question, so im pasting the same here.
I'd like to start by thanking anyone with enough patience to read it all, i have a degree in electronics but my daily job is in a completely different field so,
with my knowledge aging and rotting away, i want to double check with you experts to make sure i don't do any dumb mistake.
I recently had the luck to acquire a batch of still sealed laptop batteries from a closing office.
These were in a spare-parts stock and have 0 cycles on them as they were never used.
I opened all the batteries and harvested the cells, then used my D2 Digicharger to charge them all, plus estimate the capacity by measuring how much time they took to charge (the D2 uses constant 500mA for charging).
I have in total 232 Cells, but they are of different capacities.
I split them in 2 batches:
130 Cells (labeled Old Batch) are those i harvested almost exactly a year ago and after fully charging them i put them aside waiting to get more (measured most of them today, after a year of storage they dropped to 4.10-4.16V so they look healthy).
102 Cells (labeled New Batch) i harvested and charged in the last 2 weeks.
My objective is to convert my bike to kinda-hybrid, it has quick-release front tire, so i wish to buy a front wheel hub motor that i can connect and disconnect quickly in order to "choose in the morning" if for the day i need it electric or pedal-only.
The motor controller will be connected via Ubolts and the battery will be on the package carrier secured with bolts and straps.
I was thinking of using one of these motors.
Currently i usually cycle 50-70 km on pedals, i wish to achieve a similar (or more if possible) range with electric (so with minimum pedaling), but my main doubt is whether or not 36V is enough to overcome steep-ish hills or if i should get a 48V motor instead.
I attached a PDF/Excel of all the cells i have, if they were all the same i wouldn't have any problem, but they are different capacity/C-Rate, so i'm not sure how to proceed.
If i am to combine only the NCR18650 i have (they are the cells i have most of with 99 identical ones), i can do a 13S7P using 91 Cells, that would give me a 48V 19.60Ah (917Wh cca.) pack and im not sure these numbers are sufficient for the range i wish to achieve.
If instead i am to combine different cells, what would be the best way to do it?
First thought goes torward combining them in the parallels, so to have multiple parallels of same capacity that will self balance and then series them (so for example 7P of NCR and an additional 2 UR18650FM that are similar specs so to have a 13S9P or more), or more advancedly as rePackr - 18650 pack builder shows.
Could you please advise if it is a sound thought?
Considering i would like to have as many stats as possible, could you advise on a good BMS with sensors?
I also plan to have multiple temperature sensors inside the battery in various spots and have an ESP8266 send them to my main screen so i can keep an eye on the temperatures at all times.
Please feel free to tell me i'm an idiot or such, i wish as much input as possible to understand what can be done better, starting with motor, controller, battery plans etc.
Thanks to everyone in advance.