Do new laptop batteries in a homemade pack need a breakin?

[gaisom]

I have a bunch of new 18650 cells from laptop battery replacement blister packs that were never opened. I can't figure out whether I need to do the charge/discharge cycles required to get the best life out of new batteries. Anybody know?

 

[dnmun]

you should balance them all to the same voltage before building the pack. then the BMS will be able to balance it after that. once the pack has been balanced, you can then do several cycles.

i usually do 80% for 2 cycles. then you should make sure it is totally and fully charged on each channel before you do the first full discharge to LVC on the BMS to establish the total capacity of the cells.

measure each channel while doing the capacity test so you know which are the lowest capacity and keep a record of them for later when you have to diagnose what is wrong with the pack.

 

[dogman dan]

My very non scientific take on it has been that when I get a new pack, or I get back on a pack that has been stored for more than a month, they need some type of a break in. This is less apparent with lithium than I have seen with lead or nicads or nimh, but it does seem like you get more capacity out of a pack if it got cycled in the last week or two.

Mostly, it's a question of getting it fully balanced again, and it does seem to me like that gets done quicker if you get it close to balanced, then cycle it very gently, then balance again. Leaving cells on a balancing charger will of course be cycling the lower capacity cells that fill the fastest.

I don't know what the best, most efficient procedure for that would be on a pile of loose cells. If they are still in a pack, I'd want to do some quick low dod cycles before breaking them up and sorting them.

 

[gaisom]

I read on another post where the best breakin was several shallow discharge/charge cycles, then let sit 24hrs..balance charge and do a cycle that will use the capacity that you figure to use normally. I am leaning towards 3.7 to 4.15 as my normal operating range.

I probably won't start putting the Pack together for another month, it will take me that long just to get the batts ready, tested and the layout setup for the packs.

I have enough batteries to make two 20ah packs, so I think I will use one and carry the spare just in case. Being that I have a Sun Delta trike I can pack them pretty easily.

The trails I have 100yds from my house has no hills to speak of and there are 50 miles plus of paved surface 8 ft wide.

Youngest sun is pissed at me since I told him to get his stuff out of my old rockhounding shed so I can work on the stuff and not have it in my house or garage.