WW 52V Battery Issue

[Cuz Vinny]

Not sure if WW is using the same company here in CA, but when my first battery was damaged in shipping the 'new' battery they sent had blue painters tape over a crack in the case and scratch evidence showed it was used.
Six months later I was curious, so I checked the first battery. At first it seemed dead, display would not come on. I checked w/ a meter and it was live. Close inspection showed one of the plastic, bottom end nubs was damaged. I sanded it a bit, reinstalled and it worked.
It was 52v - near 60% charge.
The odds against two battery's in a row having a bad cell are up there with two damaged in shipping.
What are the odds of two batteries in a row with a bad BMS or having a voltage leak ???
Could this be your charger? Overvoltage damaging a cell? I'd think by now you'd know if that was it.
TPEHAK or evixone would be sources of reliable information, but I assume you resolved the matter.

I’m using the charger WW supplied with the bikes. WW currently doesn’t have replacement 52v batteries and don’t know when they will get any. I was willing to pay full price for them just because the monetary loss on the bikes is far greater than the cost of the batteries. I’m not a fan of rebuilding batteries so that’s not an option either. I’m considering parting the bikes out and just be done with the whole situation.

 

[greeno]

Dude ship my one of your battery’s and I will fix it for you for cost.
If the battery’s are lower capacity we can replace them with a higher grade.
Send me a PM if your serious.

 

[JRA]

Another option is to get a new 52v battery with 21700 cells. Drops the wh rating to 780 but I have been using one for a year and it performs very well in fact better for power and range than the stock 840wh 48v my bike came with. Contact [email protected], cost will be around $400 shipped.

 

[Fast n' Furious]

Another option is to get a new 52v battery with 21700 cells. Drops the wh rating to 780 but I have been using one for a year and it performs very well in fact better for power and range than the stock 840wh 48v my bike came with. Contact [email protected], cost will be around $400 shipped.

I was all aboard, an optimist and 21700 fanboy - until I did the math.
21700's are not an productive option.
Here's the cases and here's the math.

For 21700 'DP' cases:
DP 4C (40 cells capacity) = 14S2P (28 cells usable).
DP 5C (52 cells capacity) = 14S3P (42 cells usable).
DP 7 21700 (70 cells capacity) = 14S4P (56 cells usable) - and don't think that will fit on my bike.

Conclusion: Reention DP cases are physically incapable of holding as many of the larger 21700's as smaller 18650s.

Example:
DP 6 21700 (same capacity as DP 5C) holds up to 52 21700 cells = 14S3P (42 cells usable @ 52v).
21700 @ 5000mA ea. = Max 15A.

DP 6 18650 holds up to 70 cells = 14S5P (70 cells usable @ 52v)
18650 @ 3200mA ea. = Max 16A.

At this point - munching on crow feathers - I went into denial. 'Who cares 21700's take up more room than 18650's? I can live with less range. It's a good trade-off for less weight', I rationalized.
So (utterly biased) and full of irrational exuberance I set out to prove then conclusion I started with (before gathering facts) was valid.
Predictably I failed.

5000mA 21700 = 70gms.
3200mA 18650 = 40gms.
14S3P = 42 21700 cells, weighing 2940gms w/ 15A
14S5P = 56 18650 cells, weighing 2800gms w/ 16A

Stubbornly I thought: 21700's in a shrink wrap pack will have better figures.
Again I was wrong.
21700 (5000mA) 14S4P = 3920gms w/ 20A
18650 (3200mA) 14S7P = 3920gms w/ 22.4A

The 21700 numbers don't add up to any improvements I want.

Fn'F

 

[Ravi Kempaiah]

5000mA 21700 = 70gms.
3200mA 18650 = 40gms.

How to Know a Fake 18650 Battery

How to Know a Fake 18650 Battery: An average genuine 18650 batteries will weigh about 45g and no nothing less than 42g. You can see I have a fake 18650 battery in the pic weigh 32g only and the genuine 18650 battery weight 45g. Some genuine 18650 battery can weigh more than 50g. Goo…

www.instructables.com

A-grade 18650 cells would be 45g or 47g in some cases.

I’m using the charger WW supplied with the bikes. WW currently doesn’t have replacement 52v batteries and don’t know when they will get any. I was willing to pay full price for them just because the monetary loss on the bikes is far greater than the cost of the batteries. I’m not a fan of rebuilding batteries so that’s not an option either. I’m considering parting the bikes out and just be done with the whole situation.

If there is anything we can do to help, don’t hesitate to reach out.

 

[greeno]

JRA that extra snap you’re referring to is the increase in volts from 48 to 52 Not the battery type in most instances.

 

[scrambler]

The energy density of the 21700 is only marginally better than the energy density of the 18650 cells (about 5% I think).
As a result, space / Capacity wise, they will only be beneficial if they allow a better occupation of the space.

They can also be beneficial for batteries that need to provide high continuous amps.

 

[Cuz Vinny]

How to Know a Fake 18650 Battery

How to Know a Fake 18650 Battery: An average genuine 18650 batteries will weigh about 45g and no nothing less than 42g. You can see I have a fake 18650 battery in the pic weigh 32g only and the genuine 18650 battery weight 45g. Some genuine 18650 battery can weigh more than 50g. Goo…

www.instructables.com

A-grade 18650 cells would be 45g or 47g in some cases.



If there is anything we can do to help, don’t hesitate to reach out.

Are you getting any new 52V batteries back in stock?

 

[JRA]

JRA that extra snap you’re referring to is the increase in volts from 48 to 52 Not the battery type in most instances.

I actually have both 48v, 720wh, and 52v, 780wh, 21700 batteries and started off with the stock 840wh 18650. Both are snappier and have better range than stock. YMMV

 

[greeno]

I was kinda comparing apples to apples.

Example #1: I started off making 52v battery packs using Sanyo GA 18650 batteries that have a rating of 3.45ahr and a discharge rate of 10a.

Example #2: For the last couple of years I have been using Samsung 50E 21700 batteries rated at 5ahr and 9.8a discharge.

Both using identical Daly 30a 14s BMS units.

Both are about the same in performance as far as I can tell. Using the 21700 batterys is the cheaper way to go now that they have become more common and have dropped in price.
Less batteries, lower cost, weight pretty much is a wash.

Load those battery's up with some higher discharge rate cells yeah you will see a difference but it will cost you with the ahr rating which will be less reducing your range.

A few years back I rebuilt up a 72v battery for a guy that had a Kranked bike and we used some high discharge 18650 cells and that thing was a rocket.