Any special treatment of new NMC pack for long service life?

[joe81]

I heard conflicting info on how to treat especially a new pack.
Let's assume cells are balanced. Should I just start charging up to 80% and discharging with moderate power until 30% SOC before recharging again (my intended average use profile later on)? Or is any of the cycling/charging fully/applying some high discharge cycles that I have heard about really beneficial for a new pack?

 

[cal3thousand]

I heard conflicting info on how to treat especially a new pack.
Let's assume cells are balanced. Should I just start charging up to 80% and discharging with moderate power until 30% SOC before recharging again (my intended average use profile later on)? Or is any of the cycling/charging fully/applying some high discharge cycles that I have heard about really beneficial for a new pack?

No conditioning necessary on Lithium packs other than balancing.

If you are ready to go, start using that profile. 80% to 30% SOC cycles will yield a longer pack life than otherwise. Also, charging your pack shortly before use will help with pack life as the longer that a pack stays in higher voltages (and temperatures), the more potential for degradation.

 

[dogman dan]

No conditioning needed except for charging to fully balanced once it arrives.

However,, I find that charging full, then discharging less 5%, charging full again several times, can result in a better fully balanced charge. New batteries can get a bit unbalanced in storage or shipping, so several very short discharges can result in a full balance a bit quicker than longer discharges.

This re balancing cycles should be done when the battery is new, or when it is taken out of storage that lasts longer than a month.

 

[joe81]

Thank you guys! That sounds very low maintenance.

Two additional questions:
- What maximum percentage or delta in voltage between cells is considered acceptable whitout the need for re-balancing? Measured at which SOC (if relevant)?
- What are the corresponding voltages for 30 and 80% SOC with NMC?

 

[redilast]

Thank you guys! That sounds very low maintenance.

Two additional questions:
- What maximum percentage or delta in voltage between cells is considered acceptable whitout the need for re-balancing? Measured at which SOC (if relevant)?
- What are the corresponding voltages for 30 and 80% SOC with NMC?

Depends on the battery and its nominal voltage. Some are 3.6v, 3.65, 3.7, 3.75, 3.8 etc. But roughly 4.0v down to 3.6v or so. But these are idle voltages (not under load).

 

[dogman dan]

Re the question what is balanced, or balanced enough. That's a question many disagree about. Do you need to balance to .01v? Not for most applications you don't. You don't need that fine a balance at all if you don't run the battery down to 100% discharged, and it's also debatable whether your measuring or charging tools are really accurate to .01v anyway.

If you plan on a routine of charge to 80% discharge to 30%, you could be out of balance to .5v and it would not matter very much, since you are leaving a lot more than that in the 30%.

But I'd say keeping it well within .1v to .05 volt is a reasonable goal, and balance to .01v a few times a year at least. That's a charge to 4.2v for measuring the balance btw. Most cells that charge to 4.2v can go to 4.3v without permanent damage, so that is where I get the maximum of .1v from. Don't want it so far off you charge to 4.31v or higher. .05v off means your highest possible charge would be 4.25v on a charge where most of the cells are at 4.2v. You can definitely live with that so aiming for balance to .05v is plenty good enough for almost all applications. You aren't racing.

 

[Tordnado]

Hi!

My understanding of optimum charging for maximum number of cycles is keeping the battery in the "middle" of its charge. Say 20-90% or 30-80% depending how much overcapacity one has but how do you do that in the easiest way? I am commuting and I want to keep it as simple as possible. Using a timer to turn off the charger before the battery is full?

 

[999zip999]

All said it should be left on the charger for some time for the bms to first balance the battery when new. Most batteries die because people forget to charge there battery or abuse it. Or using it above it's ratings.