roswitha mamutschka
New member
- Joined
- May 15, 2018
- Messages
- 6
Hi all!
Im trying to make my first pack from used laptop cells.
Its gonna be 36v for a 350w ebike. Now a dumb question: how do i calculate how much cells i need in paralell for that? I=P/U? Would mean about max 13A draw depending on the current voltage? Am i calculating this right? I cant figure out what im doing wrong.
So i got this charger for testing: "AccuPower IQ328+ "
I started testing with 500mAh charging and 300mAh discharge. First it charges to 4.2V than discharges down to 2.8V and then charges to 4.2V again. Only at the end u can see the discharged and charged capacity. And somehow strangely the discharge capacity is mostly about 50-100mAh higher than the charged capacity. how can this be?
I already tested about 20 cells like this and there were only one or two where the discharge capacity was lower than the charged capacity.
I tested some with 700mAh charge and 500mAh discharge, but same resuts. is this normal? can i just ignore that?
Did i get a bad charger? And also this charger heats the cells up so much, i can only figure out a cell is bad if it is already kinda burning hot.
Anyway to speed up the whole process i started testing 2 cells in paralell in one slot from the charger as they came out from the laptop pack in a pair. But now if i wanna put them together with all the single cells i started testing with 500/300 charge/discharge i now test a pair of cells with 1000/500. which would mean each cell of a pair is tested with 500/250. Is this close enough to put them togeher in a pack with the single cells i tested with 500/300? And i thought i will just let these pairs togeher in paralell in the new pack too. so it shouldnt be a problem right?
i guess i just cant go now and test all my remaining single cells with 700/500.
500/300 is really slow..
so i should really have the same testing conditions for all cells to put them togeher in a pack?
I guess i should have just gotten 2 opus for 20 more with a cooling fan, but i didnt concider that.
I just got this charger fast local.
Oh yea and all the pairs i tested with 1000/500 had a higher charge capacity than discharge capacity. thats how it should be i guess?
And then i have another question about charging.
Lets say i have 10cells in paralell. How can i tell what will be my max charging current? I look at the specs of all cells and go with the lowest *10 ? So for example 1,6A*10 would be 16A.
I guess 1A per cell would be still fast enough and it would extend the cell life.
But now what charger do i get that can balance charge a 10s battery with at least 10A? kinda safely?
I didnt really find a 10s charger so i tought: cant i just get two 5s chargers? And like the middle of the batterypack is the Plus for one charger and the Minus for the other charger? Right? Doas it work like that?
I hope u understand what i mean i dont really know how else so describe it.
Here is what i found maybe u can recommend me something better:
Either two of these: "Turnigy Accucel-6 80W "
Or this one: "Turnigy TQ4 4x6S " alltho this olny can do 6A max.
And i dont really wanna get a BMS cause i wanna have the option to make more different sized packs without having to buy a BMS for every single pack. And also ubalance charge to 4.1V with all these hobbychargers.
Also what is the max temprature a cell should reach? 60 degrees? Wouldnt it be good to have a temprature sensor with alarm at a certain point? I found this: "MagiDeal W1401 24V Digital Thermostat Temperature Controller Switch Sensor Module "
There are just no instructions or a manual but it looks like what i would need and cheap.
Sorry for all this basic questions, i researched alot but i couldnt really find answers for all this stuff.
And i dont really know where to put this thread i got questions about everything kinda. But atm my biggest issue is how to correctly test all cells and having no concerns about putting them together in a pack.
And then how to build the pack? I tought about something like this with magnets: battery pack 18650 cells. No soldering to the cells only magnets
If i have a draw of 10A or less for 90% of the time and 10cells in paralell would mean 1A per cell. Shouldnt be too bad or? Worst case ill just lose some energy at the connection at higher currents i guess.
Well i hope this aint too much questions at once and u can help me maybe and tell me if im doing something wrong.
Thanks!
Im trying to make my first pack from used laptop cells.
Its gonna be 36v for a 350w ebike. Now a dumb question: how do i calculate how much cells i need in paralell for that? I=P/U? Would mean about max 13A draw depending on the current voltage? Am i calculating this right? I cant figure out what im doing wrong.
So i got this charger for testing: "AccuPower IQ328+ "
I started testing with 500mAh charging and 300mAh discharge. First it charges to 4.2V than discharges down to 2.8V and then charges to 4.2V again. Only at the end u can see the discharged and charged capacity. And somehow strangely the discharge capacity is mostly about 50-100mAh higher than the charged capacity. how can this be?
I already tested about 20 cells like this and there were only one or two where the discharge capacity was lower than the charged capacity.
I tested some with 700mAh charge and 500mAh discharge, but same resuts. is this normal? can i just ignore that?
Did i get a bad charger? And also this charger heats the cells up so much, i can only figure out a cell is bad if it is already kinda burning hot.
Anyway to speed up the whole process i started testing 2 cells in paralell in one slot from the charger as they came out from the laptop pack in a pair. But now if i wanna put them together with all the single cells i started testing with 500/300 charge/discharge i now test a pair of cells with 1000/500. which would mean each cell of a pair is tested with 500/250. Is this close enough to put them togeher in a pack with the single cells i tested with 500/300? And i thought i will just let these pairs togeher in paralell in the new pack too. so it shouldnt be a problem right?
i guess i just cant go now and test all my remaining single cells with 700/500.
500/300 is really slow..
so i should really have the same testing conditions for all cells to put them togeher in a pack?
I guess i should have just gotten 2 opus for 20 more with a cooling fan, but i didnt concider that.
I just got this charger fast local.
Oh yea and all the pairs i tested with 1000/500 had a higher charge capacity than discharge capacity. thats how it should be i guess?
And then i have another question about charging.
Lets say i have 10cells in paralell. How can i tell what will be my max charging current? I look at the specs of all cells and go with the lowest *10 ? So for example 1,6A*10 would be 16A.
I guess 1A per cell would be still fast enough and it would extend the cell life.
But now what charger do i get that can balance charge a 10s battery with at least 10A? kinda safely?
I didnt really find a 10s charger so i tought: cant i just get two 5s chargers? And like the middle of the batterypack is the Plus for one charger and the Minus for the other charger? Right? Doas it work like that?
I hope u understand what i mean i dont really know how else so describe it.
Here is what i found maybe u can recommend me something better:
Either two of these: "Turnigy Accucel-6 80W "
Or this one: "Turnigy TQ4 4x6S " alltho this olny can do 6A max.
And i dont really wanna get a BMS cause i wanna have the option to make more different sized packs without having to buy a BMS for every single pack. And also ubalance charge to 4.1V with all these hobbychargers.
Also what is the max temprature a cell should reach? 60 degrees? Wouldnt it be good to have a temprature sensor with alarm at a certain point? I found this: "MagiDeal W1401 24V Digital Thermostat Temperature Controller Switch Sensor Module "
There are just no instructions or a manual but it looks like what i would need and cheap.
Sorry for all this basic questions, i researched alot but i couldnt really find answers for all this stuff.
And i dont really know where to put this thread i got questions about everything kinda. But atm my biggest issue is how to correctly test all cells and having no concerns about putting them together in a pack.
And then how to build the pack? I tought about something like this with magnets: battery pack 18650 cells. No soldering to the cells only magnets
If i have a draw of 10A or less for 90% of the time and 10cells in paralell would mean 1A per cell. Shouldnt be too bad or? Worst case ill just lose some energy at the connection at higher currents i guess.
Well i hope this aint too much questions at once and u can help me maybe and tell me if im doing something wrong.
Thanks!