Possible sources for battery repair?

[Mark911]

The 17 pack is made of four modules connected in series. Each module is configured 21S 6P.

Thanks Matt.

 

[MattB]

The 17 pack is made of four modules connected in series. Each module is configured 21S 6P.

Thanks Matt.

No problem Mark!

 

[MattB]

I got ur point about the 110lb pit-bike/Chinese bike, was just pointing out its a toy in comparison to an Alta. Alta has more than 20cells - what’s the 18650 count? 504 ... 126s4p?

126s4p = 529v and 504 individual cells per pack x 4 packs in the entire battery = 2116v total and 2016 individual cells total.

I think your slightly off.

 

[schwankl]

from Mark taking it apart we saw 126 cells per layer and 4 layers = 504 cells in the entire pack... it gets more interesting here w/ the 96 hardwired (16s6p) and 30 not per layer: https://altaownersforum.com/threads...et-the-battery-management-tech.288/#post-3411 ... other place saw it reported as a 355v 96s: Alta Motors? Heres what I found | ElectricMotorcycle.com | The Electric Revolution Starts Here ... just trying to learn more.

 

[Mark911]

At first I though the fact that many of the cells were connected "inter-board" instead of daisy chained meant something special was going on. After some head scratching and inspection I've come to the conclusion that going inter-board was needed simply because that's what was required to fit the external size and packaging requirements. The result is 21S x 6P. The total voltage of my individual modules was around 84V (almost fully charged) with individual cells at 4v. It all adds up.

 

[Mark911]

Thanks Mark

Snydes,
One of the things I mentioned in my "Technical Review" was the potential problem with constantly charging between moto's without allowing the pack to fully charge. Most of the cell balancing is probably done towards the end of the charge cycle. If the pack never gets to this point before the next discharge cycle some cells can get way out of balance. If this is the case, it might take many charge-to-full cycles to re-balance the pack as the balancing current is typically pretty small. Have you tried successive charge cycling to full?

 

[snydes]

Snydes,
One of the things I mentioned in my "Technical Review" was the potential problem with constantly charging between moto's without allowing the pack to fully charge. Most of the cell balancing is probably done towards the end of the charge cycle. If the pack never gets to this point before the next discharge cycle some cells can get way out of balance. If this is the case, it might take many charge-to-full cycles to re-balance the pack as the balancing current is typically pretty small. Have you tried successive charge cycling to full?

I have completely charged one time since the fault. Additionally, it took a VERY long time (a full 45 minutes) from the time the charge meter showed full (and the chargers fan shut off) until the bike actually shut off.

 

[Mark911]

you might want to try plugging it in a few times and let it try and balance. The BMS should keep it from over-charging. You never know, it's a long shot.

 

[MattB]

Snydes,
One of the things I mentioned in my "Technical Review" was the potential problem with constantly charging between moto's without allowing the pack to fully charge. Most of the cell balancing is probably done towards the end of the charge cycle. If the pack never gets to this point before the next discharge cycle some cells can get way out of balance. If this is the case, it might take many charge-to-full cycles to re-balance the pack as the balancing current is typically pretty small. Have you tried successive charge cycling to full?

This is exactly why I favor the slow charger over fast. If I have the time, I will always slow charge. Balancing cells can take a long time, especially if the cells are not matched properly. As the indivudual cell resistance goes up with age, you will see the pack balancing take a lot longer. My other RC chargers can charge a 6s pack at 14A but can only balance at 1A. I generally get 200 cycles out of a Lithium Polymer pack but I am really hammering these packs with 80A continuous and close to 200A bursts.

 

[Rix]

Yes, we all know its a toy compared to the Alta. That's pretty obvious.

Yes, Alta has many more than 20 cells, it was never stated that the Alta had 20 individual cells. Rix was considering using a 20s 84v battery in his Alta when the stock battery is 84s 350v. It doesn't matter if you have a million cells in a 20s pack, you are still at a very low voltage for the operation of the Alta.

The Alta is 84s - 350v, as far as the actual cell count, we know that the pack is 5.9kWh.... we just need to know the capacity of each individual cell to determine how many individual cells. Without knowing the exact individual cell capacity we can't finish the math. However, Mark911 can probably tell us as he has one disassembled.

If the above was confusing, read up a bit on series and parallel battery configurations. Here are the cliff notes -

Series - If the cells are connected in series, the voltage of the battery will be the sum of the cell voltages. The Alta technically has 84 x 4.2 volt "packs in series" of 18650 cells. How many cells are in each "pack" is unknown without actually counting or knowing the individual cell capacity.

Parallel - If the cells of a battery are connected in parallel, the battery voltage will be the same as the cell voltage, but the current supplied by each cell will be a fraction of the total current. Individual cell capacity and the count of those individual cells configured in parallel is where we get our 5.9kWh rating.


Lets say each cell is 4.2v 1000mah

Parallel :
++++
* * * * = 4.2v 4000mah
- - - -

Series :
+ - + -
* * * * = 16.8v 1000mah
- + - +


And we can also do this.....

++++
* * * * = 4.2v 4000mah +
- - - -
************************* = 8.4v 4000mah
++++
* * * * = 4.2v 4000mah -
- - - -



I hope that helps clarify some things.

All true, but lets say I replaced everything and went with a 20S 25P pack made from 25R cells. Hot off the charge would give me an 84volt 63ah pack with a potential discharge rate of 630amps DC (25R cells have a 10C rating). Depending on volt sag, we have a potential of 50kw or so of power HOC and of course it would be less at nominal and not nearly as efficient as our current set up. To go this route and make it work, everything would need to be replaced. I would never consider doing this unless I couldn't get my current setup repaired or replaced.

 

[TonyWilliams]

Intesting perspectives on the battery.

First, I have to say that getting zapped by 354 volts will likely kill you, AND it will hurt the entire time you’re dying.

Don’t screw with the high voltage stuff if you don’t know what you’re doing. (Or get a life insurance policy payable to me).

The “R” bikes have about 51.7 pounds / 23.5kg of cells

46.6 grams * 504 cells = 23.5kg

(21S * 6P) * 4 modules = 504 cells

That’s only 5.4kWh:

504 * (3000mah * 3.6V) = 5.44kWh

Brand: Sony Energy
Model: US18650VTC6
Size: 18650
Nominal Capacity: 3000mAh
[ my edit - typical cutoff 2.5V ]
Nominal Voltage: 3.6V
Maximum Voltage: 4.2V
Discharge: 15A Maximum Continuous, 30A Maximum Continuous with 80 deg C cutoff
Style: Flat Top
Protected: NO, UNPROTECTED
Approximate Dimensions: 18.5mm x 65.2mm
Approximate Weight: 46.6g

54kW (72hp) = 15A * 3.6V
108kW (144hp) = 30A * 3.6V (80C / 176F temperature limit)

Let’s just say that power isn’t a factor here. These cells are simply incredible.

I’d love to see the voltage sag at 30A.

 

[Rix]

I’d like to start preparing for the worse and looking for potential people/places that may be able to service and repair these batteries should it come to that.

Do we have any thoughts or ideas? Maybe a competent forum member that would consider a side job? Even best case scenario with Alta at some point batteries will be out of warranty and will eventually need attention, so this would be in all our best interests.

And whoever we can get to build these packs, we don't want this happening to our Redshifts.

 

[snydes]

 

[privateer703]

Just a thought, but I don't think we will be able to replace cells within a "pack". looking at the battery disassembly thread, the picture that shows dates and signatures for some actions shows a picture that says "epoxy". I think the batteries were all set in an epoxy bed, which means they aren't coming out. It looks like you might be able to replace a "pack", one tier of batteries, but not individual cells.

 

[Redwolf]

And whoever we can get to build these packs, we don't want this happening to our Redshifts.

View attachment 1700

Who's got the marshmallows??

 

[snydes]

Just a thought, but I don't think we will be able to replace cells within a "pack". looking at the battery disassembly thread, the picture that shows dates and signatures for some actions shows a picture that says "epoxy". I think the batteries were all set in an epoxy bed, which means they aren't coming out. It looks like you might be able to replace a "pack", one tier of batteries, but not individual cells.

I don’t doubt this. Someone would have to produce a new module to stuff with new cells.

 

[TonyWilliams]

Arranging the cells in a container is relatively easy. Low on the list of concerns.

Making it work with the existing BMS might be a bigger issue.