Cycle life tests of High Energy density cylindrical cells

[BatteryMooch]

Vapcell F63 and N41 died after 450 cycles at 100% DoD. I asked Vapcell what they think about it, given their claim of 1,000 cycles. I think I surprised them, but we agreed that I had "misunderstood" their specification where they meant their cycle life claim for cycling at 70% DoD.

“Ahh…you “misunderstood”…yea, that they were misrepresenting (I’m being polite here) those cells.

 

[BatteryMooch]

@Pajda whats the minimum SOH percentage you would still consider for a common off the shelf cell safe to use?

PMJI, the datsheet is always a great place to start as the manufacturer will not set a cycle life capacity loss spec lower than what is generally accepted as “safe” (always some level of risk when using any cell) for a cell that is otherwise undamaged.

 

[BatteryMooch]

- BAK 55E also has started to deteriorate, which is a somewhat unexpected result, as the BAK 58E is still holding up.

I’m also surprised by this as the ultra-high capacity cells are often more “delicate”, handling abuse worse than their lower capacity brethren.

 

[BlueSwordM]

I’m also surprised by this as the ultra-high capacity cells are often more “delicate”, handling abuse worse than their lower capacity brethren.

The BAK 58E is likely a newer cell than the BAK 55E.

 

[Pajda]

@Pajda whats the minimum SOH percentage you would still consider for a common off the shelf cell safe to use?

80% and based off of IR.

In short, @BlueSwordM is right.

This parameter is highly dependent on the application. This means that in some applications, you will hardly notice the 80% SoH, while in others, the battery will become practically unusable. A typical example is an impact wrench. If it can't loosen the screws on your car's wheels, then it's useless to you that it still has more than enough power to loosen hundreds of M3 screws...

However, from a product warranty perspective, it was necessary to state a specific number. Today, the unwritten rule is 70% SoH, which is interpreted as a decrease in capacity to 70 % of the nominal value or an increase of internal resistance by 100 % (double the nominal value), whichever occurs first.

This value is more convenient for battery manufacturers, because a battery in this condition is truly worn out and the difference between this state and a new battery is obvious at first glance. From the customer's point of view, a value of 80% SoH (80% capacity drop or 50% IR increase) would be more favorable.

 

[freesty]

Whats your thoughts on Samsung 58e (CC5493F101)?
Is it still a cell to consider, when available for a decent price and usually do 90% DoD? Or better go with 4800mAh+ cell like EVE, BAK or DMEGC?