Mixing Older and Newer Cells

[EZwryder]

I am jonesing in the worst way now to get some lithium power in this EBR, but I just cannot drop $4K for all the cells I need to get to 7.2 kw.

But I sorta had an epiphany just a while ago when I was pricing them out, again, for the 100th time, just in case the fundamental principles of mathematics had changed and I could somehow afford a batch of TS 100 AH cells.

Let's say I went with Headway cells instead, and I got 48 of the 10 AH cells. That would get me 20 AH for a little under $1K. I could probably swing that. If I add depth to the pack 24 cells at a time, would it matter if I had a mix of cells with different levels of use? Would it matter if some packs were 10 AH and some were 16 AH?

I also like the form factor flexibility and the higher performance, but most importantly, it seems like it's an approach I could build on a bit at a time.

[EVcycle]

"Would it matter if I had a mix of cells with different levels of use?" Not advisable, but doable as long as they are the exact same cells.
"Would it matter if some packs were 10 AH and some were 16 AH?" Yes it matters and I would not advise it ....ever.

Will you be using a BMS?


EV Ed

[EZwryder]

Yes, I will be using a BMS. Yeah, now that I think about it, disregard the Q about different capacities. I realize that's not a good idea. But what are the drawbacks of adding on capacity in steps? Why is it not advisable? Just wondering.

[EVcycle]

It will really make a difference when the first group of batteries starts to lose its capacity at the end of its lifetime. Also you have to break in new batteries when you add more to the group.
Every time you add more capacity, you will need to go through the break in procedure of running them "lightly" until they are fully awake and running at full capacity.
The best thing to do is determine the full range of the first pack. When you add more do not exceed that range for at least 30 cycles and no hard acceleration.
It can be done effectively, as long as you do it correctly.

Headways are really good batteries. Once you get them happy, they work great.

[frodus]

your battery pack is only as strong as the weakest cell.

I'd say you'd be better off just saving up money to buy them. Manzanita gives price breaks on larger orders too, so that could help save some moolah. email me via my website www.evfr.net and I can see what I can do for ya.