Hello everyone, i will try to make a thread about how to choose batteries for your project
So guys on the forum will be able to understand better how to get the best value for money.
Here are some parameters need to consider when you choose you battery.
- discharge rate ©
- working voltage
- number of cycles
- using BMS / yes or no
- budget - price you have for your project
- voltage sag - how low the voltage drop when you drain power from the battery pack - or in simple words to what voltage the voltage drop when you’re skate is with load.
It is important to understand you need to find the best solution for you’re project with out exaggerate with over kill battery parameters but not also choose batteries with lower performances for your project.
Example: you would like to build electric skate board with those parameters:
- working current 30A
- peak current 50A
- nominal voltage 36V
- capacity 10AH
- motor working power 1100W
- peak 1800W
I choose 18650 cells for this project - but how to choose the right cell?!
If we know we need cells which can handle 30A working current at 10AH capacity its 3C -
It is better to choose cell which can do a 15-20% more to enjoy healthy battery pack for long time.
So we need cells which can do 36A working current at 10AH capacity which is 3.5C at least.
We can choose Samsung 30Q for example which is rated 6C
It is important to understand there is no point to choose above 6C rated cells and pay more for more expensive cells
For example Sony VTC6 is over kill for this project and you spend more money for no good reason.
But from the other side not be cheap for yourself and choose cells rate lower than 3.5C.
Conclusion: choose the closest cells rated close to your project power, do not go over with high rate cells which won’t give you anything different, but do not go lower than needed.
*if you choose to get cells with less weight, more cycles, or smaller size, more safer - its ok to pay more for those.
if you wish to have many cycles and have battery pack can work 2-3 years but you do not care about size, weight, high prices- you should go for lifepo4 cells OR Lithium prismatic cells.
if you wish to have the max power for the size and weight , an pretty standard price, less safety you should go for Lipo
if you wish to go for the balanced option - small size , light weight, medium cycle life and good price point you should go for li-ion NCM 18650/ li-ion NCM pouch cells / Li-ion to match the power on your project.
Typical sources to get 18650 ‘bare’ cells:
https://eu.nkon.nl2 Pros: Good variety & Prices, Offers to add nickel tabs for extra fee, Volume discounts
Good luck for all the new and old builders. Have fun skating