DCkiwi said:
1/ if you can, use all cells with same make/model. this will spread the load evenly throughout discharge curve. IE panasonics give out more power up high (>3.9V) while LG's give out more down lower (3.7-3.9V) ... or is it the other way around ... anyways, hoping you get my point.
To be explicit, my context is USED LAPTOP cells, rated for LOW DISCHARGE.
Additionally there is another reason I strive for 'homogeneous' cells in my esk8 battery.. With all the cells being stressed so near to their [dis]charge limits it is essential that they all work in harmony. This specifically includes individual cell capacity. Hence a completely different beast of a battery than for instance, an 80P powerwall which might have cells with capacities that vary by 100+ %. It doesn't matter that a 2000mAH cell is charging at twice the current as its 1000mAH capacity tested parallel neighbour, because its in an 80Pa 40A battery charge is only an average cell charge rate of 500mA anyways!
To summarize -- matching thecapacities (reducing deviation) and discharge curves (brand/version) of cells in a battery becomes more important as the currents (charge or discharge) comeclose to cells max spec. Tuning a battery like this can help reduce maintenance and improve lifespan/reliability.
Iker138 said:
Okey!! Thank you a lot of for your recomendations. I agree with you that with a careful management of the trottle we avoid too much sag. Im making this bike for my and maybe to a presentation of a projects competicion. I dont wanna go at full throttle. Only sometimes. My biggest question is if it is safe. I know that the battery will not degrade fast because also i have a 250w mode in the controler so this was very beneficial to the battery. Apart of that, my rides times they are very shorts, so only discharge like %25 of the capacity. And to charge im thinking to adjust the parameter of the bms to cut-off at 4,1v. Have you any video about your skate?. Thank you and sorry for my english xD
Yes
I highly recommend you enter that competition. I recently participated in a Maker Faire (Wellington 2018) and it REALLY boosted along a lot of my projects, experience, and confidence too. We'd love to see your pictures, keep us all posted. : )
Me, I am very heavy handed on the throttle, and am more in the mode of making my stuff perform like I wanna drive, rather than the other way round. If I discharge 25% of my battery on one ride, it WAS a long ride. lol. about
the only time I would dare to charge my battery over 4.1V/cell would be to 'trick' the charger into giving full CC by raising the CV limit to 4.12V and then it would just truck through to 4.10V without slowing down at the end. But then I'd manually stop the charge and pack/ride it from there. No video on my esk8, am a bit camera shy, but I will start another thread here soon ok, not wanting to hijack this one. Your english is better than my [pick any language]. Thanks for sharing.