Why Second Life Battery Projects Are So Important For Everyone

Daveyboy

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I'm sure many of you watch transport evolved, but in case you don't, this episode from Nikkireally goes to show there is an awakening happening right now for second life batteries. Viva la Battery revolucion!
 
Thanks for the link. Not a subscriber, but the information is nice to have.
 
Sorry to burst the bubble a bit... might be just being argumentative...

"can't deliver the current" is just wrong, wrong, wrong... deleted the rest of my reponse :D

"can't drive the car to the end of the road" could have been more realistic... oh, wait, then the battery would actually be useless, even for second life projects...

"parallel wired high voltage battery array" - brilliant tech speak meaning nothing really as the packs are already internally parallel wired, guess that must be parallel parallel wired then...sarc.. or is that just 2p...

hmmm..
parallel, parallel, parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel, parallel, parallel, parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel , parallel wired battery pack. right...

I'll stop there...
 
lol :p
 
Isn't there plausibility to the fact that high C rated batteries loosing the ability to deliver. IR increases causing the inability to deliver the high rates of Current needed?
Those cells now being put in parallel result in a lower relative resistance and the and less draw on each cell and still meet current requirements.

I could be wrong.
 
Yes for 10C charging in the BYD busses as this is one of the reason they pull packs out of service. The cells will still pull more than enough to accelerate a vehicle.

If someone bought a car for the 0-60 acceleration time of 5 seconds and found that after 200 ludicrous accelerations that they could no longer accelerate at 5 seconds and were limited to 6 seconds, would you then expect the battery to be replaced even if it can still drive you 250 miles ?

Take any power wall developed by members here, put it in a comparable car with the same kWh and it would probably drive ok...

For cars the impact of IR would be seen on acceleration not decreasing miles.
 
There is a good read here about battery Impedence (IR)

https://www.mpoweruk.com/performance.htm
From the above link (should apply to all battery tech):
The internal resistance also influences the effective capacity of a cell. The higher the internal resistance, the higher the losses while charging and discharging, especially at higher currents. This means that for high discharge rates the lower the available capacity of the cell. Conversely, if it is discharged over a prolonged period, the AmpHour capacity is higher. This is important because some manufacturers specify the capacity of their batteries at very low discharge rates which makes them look a lot better than they really are.


Is this not applying to Li-ion?
Yes would impact acceleration, but also capacity as the cells no-longer are able to handle the required higher draw or would result in higher temps along with lower capacity.
 
"For cars the impact of IR would be seen on acceleration not decreasing miles. "
This was in relation to the
"can't deliver the current" statement in the youtube.. technically wrong. arguing with "current" and I have yet to hear of anyone who replaced a battery pack because they were unhappy with the 0-60 time (excluding anyone with more money than sense).

Short a 1000mAh "failed" test cell and see how many Amps you get out... very briefly... :D

The cells can deliver the current, the voltage drops (due to IR losses) and therefore the power delivered outside the cell drops, which would impact acceleration..... because they "can't deliver the power"... to accelerate fast.

Internally to the cell the electrochemical reactions still happen at the same voltage potentials, regardless of capacity and blocking of the electrodes creates internal resistance, which reduces the voltage seen at the terminals under load.

Drive the car slowly and get more range, not just because of the lower power required for the slower speed..... the IR then has less of an impact (I^2 R) : power = current x current x resistance. Less heat lost in the cells and more delivered to the terminals.

Long day... :D
 
big announcer voice "And in this corner we have....." :p
 
With modern cells, higher internal resistance when aging has been mitigated quite a bit. As an example, my Sony VTC4s from a Dyson pack that I extracted last year were 2000mAh average when I first tested them.

After a lot of abuse, soldering, testing with them, the capacity when down to 1750mAh average. And yet, when I measure internal resistance over a 10A load, it is in fact unchanged.

High drain cells almost do not get heightened internal resistance as they age AS LONG as long as you do not extreme fast charge them(+2C).

Intercalating back lithium compound ions is much harder on the cell than discharging it, so in that case, it is normal for the cell to have heightened IR, even if it is high drain.
 
Korishan you crack me up. I will stop. I took Electronics Engineering in the 90's ... so long ago and have studied powersource impedance, but hay it was a long time ago.
I am more interested in finding a correct BMS and fusing right now anyways.

Cheers!
 
Bubba said:
Korishan you crack me up. I will stop.

Why thank you! :D

No, no, continue. There's lots of information battling back and forth here. Questions get answered and answers get clarified when there's actual valid information and facts to back up those claims comes forth. Both major contenders in this thread have been very good at explaining their sides of things ;)
 
Ho, ho, ho...

Yup. I fell into that one..
 
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