Group Buy? Dr.Bass Steveo found 7s3p Module! Awesome Price!!

[kevo]

Mistercrash,
Thank you for the summary on the video. The load times for the evtv were excessive. Disappointed to hear how difficult it was for Mr. Rickard to take apart the packs. Hope ES members are able to find alternative ways to reconfigure cells

[JRP3]

I wish Jack had dug a little deeper, but I'm sure the people here will. If he had dremeled off the weld on the tabs to see how much tab was left to work with it would have been informative. I'd think you could figure a way to clamp in a new cell to the existing bus bar. The band doesn't seem like big deal, just drill out the weld.

[kevo]

JRP3 wrote: I'd think you could figure a way to clamp in a new cell to the existing bus bar.

Not ideal, but I suppose given the moderate weight (for ebikes anyway) could be an option. I'm waging (at least hoping) once units arrive people will step up to the task.

[mistercrash]

I wish Jack had dug a little deeper, but I'm sure the people here will.

Exactly what I thought when I watched the video. Many in here don't give up so easily.

Edit: I want to make clear that I'm not insinuating that Mr. Rickard is a quitter. From what I've seen from his videos, I didn't watch all of them, he has been tinkering for quite some time with A123 cells lately and I feel he just didn't want to waste any more of his time with this module he got.

[deVries]

The 28s3p "bare" module weight *not* counting the cells is just under 18-lbs.
Cell weight is just below 89-lbs. 84 cells x 480g.
Total module weight is 106-lbs. EDIT: 106-lbs is only referenced verbally on video from Jack Rickard's 28s3p module. So, all numbers depend on the accuracy of his measurement. The weights below should *not* be on the low-side or underestimated, imo, so actual weights may be very slightly less than what is predicted below.

7s3p packs are therefore going to weigh about 1/4 the above numbers:

The 7s3p "bare" module weight *not* counting the cells is just under 4.5-lbs for module only.

21 cells add about 22.5 lbs, so total weight for a 7s3p module will be about 27-lbs or slightly less.

[kevo]

Can't wait to hear the reviews of ES members on this Suspect a 'Gold Rush' phenomenon will occur once the revisions are confirmed

[njloof]

Suspect a 'Gold Rush' phenomenon will occur once the revisions are confirmed

After watching "Deadwood", I wonder who really makes money in the 'Gold Rush'.

[Sutho]

I think that as long as people purchase with their eyes open and expect that these modules could have problems, they won't be disappointed. I purchased 20% extra and expect to have to do some mods or repairs.

Although.....I'm not liking Jack Rickards comment about the modules not being new. I had assurances in numerous emails that the ones I will receive are 100% new.

[Ypedal]

New .. to YOU !

[deVries]

Although.....I'm not liking Jack Rickards comment about the modules not being new. I had assurances in numerous emails that the ones I will receive are 100% new.

Here are a few critiques I have about that video:

1) The video is shot too far away to see any detail on the module or its parts. No good close-ups of anything!

2) Rickard expresses a lot of opinions that jump to conclusions, when there may be a solution, perhaps, not that difficult for many ES members to solve.

3) There were 2 low cells out of 84. About 2.4% low. He cuts/edits the video saying he will do a "bottom balance", and I think Doctorbass is questioning whether or not that is a good idea or not? When the video begins again after (we can assume) he did the "bottom balancing", we find at least one cell completely died. Did his bottom balance method kill this weak cell?

4) Rickard has not convinced me in the least that these cells cannot be removed & the pack repaired.

5) He really gave no evidence that the pack was used/new "whatever". IMO. (Just mentions some tiny dings in some aluminum & maybe a "dusty" plate/cover. Again, no close-ups to see anything. )

He did mention the module was well packaged in the wooden crate, so it seems care is being taken to protect the modules during shipping.

You can search on "dremel" in this thread, and learn what I think will be the key to get these cells apart. If we can separate the cells cutting between the tabs parallel to the tabs between the bus bar ridges in the middle of those "valleys" in that gap between, then it may not be that difficult to repair. IMO.

Sutho, at least they did guarantee to replace a bad module for free (plus shipping), so that's a really good deal, IMO, if they honor that warranty. IMO.

[JRP3]

I'd say it's a fair bet that these are available because of the defective pouch construction problems so you can count on some defective cells in each module, and a lot of these were probably installed in cars, so they will be used, but probably very lightly.

[deVries]

One thing about pricing the 28s3p is: Rickard said the module cost him $850 (+shipping).

Wow, $850 is a much lower price than what others have been quoted or paid, so you might consider trying to negotiate for this lower price.

[cwah]

The 28s3p "bare" module weight *not* counting the cells is just under 18-lbs.
Cell weight is just below 89-lbs. 84 cells x 480g.
Total module weight is 106-lbs. EDIT: 106-lbs is only referenced verbally on video from Jack Rickard's 28s3p module. So, all numbers depend on the accuracy of his measurement. The weights below should *not* be on the low-side or underestimated, imo, so actual weights may be very slightly less than what is predicted below.

7s3p packs are therefore going to weigh about 1/4 the above numbers:

The 7s3p "bare" module weight *not* counting the cells is just under 4.5-lbs for module only.

21 cells add about 22.5 lbs, so total weight for a 7s3p module will be about 27-lbs or slightly less.

Thanks for this information

27 lbs is still quite heavy for a bike. I'm trying not to go over 11 lbs for batteries

Wondering if it would be cheaper without module.

[deVries]

I'm trying not to go over 11 lbs for batteries

Wondering if it would be cheaper without module.

10 of these cells would get you about 36v & weigh about 11-lbs w/20Ah. So, yes, buying just the cells & building your own pack is the way to go IF your 11-lb requirement is a high priority. Your final battery weight will, of course, be more than 11-lbs & depends on the design/materials you use to make the battery.

[oatnet]

FYI guys,
Jack Rickard discusses the A123 module he ordered from China in this week's video starting at 24' 25"
http://www.evtv.me/vidarch.html

Thanks for posting that SF!

It was nice to see one of the actual 28s3p packs, and see a report of 106lb. The cells should weigh about 89lbs, so the packaging adds @17lbs. While he says he only paid $850 for the pack, he talks about it being a "few thousand dollars", complains about shipping and says he would sell it for $2,500, which is way more than anyone here paid. I think he committed the classic error I mentioned, by drilling a Chinese vendor on cost, who more than made up the difference in shipping and quality of product.

He criticises the separator panels for being "flimsy", so I guess he doesn't realize they are not structural, but intended to be further enclosed in a protective structure. He talks about the cells "hanging from the tabs", when they are held in place with compression. It sounds like he is comparing them to some other product he is using/promoting (green energy 12v?).

I was suprised to see this guy "bottom balancing" since it is widely regarded as ineffective and bad for cells. If I understand correctly, he did a bulk discharge of almost 60ah from a new, unknown pack while monitoring pack voltage but ignoring the cell voltage. This sounds like a sure-fire way to kill a cell, although maybe this pack was sold because the BMS detected that failing cell.

I might be tempted to simply bypass a failed cell with (4) 10ga wires (4ga equivalent) between the good cells and leave the 3lbs of dead weight sit in place, but in no way is that the end of the pack. Replacing a failed cell is doable but it will take some effort. The stainless steel compression band issue is familiar from the old Vectrix pack surgery threads, and manageable. It might be a challange to manage all the trays and lasered together cells. Yes, one cannot solder the tabs of these cells, and tig would heat-damage the cells, but I have posted a thread on spot-welding the tabs that is effective.

He keeps talking about how the cells run cool at a 45a, but this is only a 0.75c discharge so I don't see that as a relevant data point; I already know that in small ebike packs at 6c I don't have a heat issue, but I am curious how this will hold up at 10c in a 300 cell pack. He also mentions how the typical Electric car pulls 100a-150a - which strikes me as odd, I see higher continous discharge at 165v on my 480lb Vectrix motorcycle and my VW bus conversion. Maybe he is talking about slow speeds, or high voltage with 384v AC systems, KW would have been a more useful metric.

I am going to use my packs on car conversions at 49s, so I didn't realize that folks here were planning on harvesting the cells from them instead of using them intact in the modules. I think it will be pretty easy to dremel off the "Buss Bars", open the case, and extract the cells, but I had a tough time working with the short tabs, maybe you will do better.

[zEEz]

I'm putting a HUGE effort in NOT trying to order at least a single 7s3p pack to
rewire as a 18s1p for my e-pocketbike that would really shine with 20Ah and 68v.

Point is ... Do I really need it? probably yes

I would safe bet it is possible to savage out 18 working cells from the 21 composing a pack.
Perhaps somebody will prove me wrong ... but I see this offer as a sound one ...

So I'm eager to know how the early adopter experience is going and perhaps I'll let my
shopping spree addiction side to take control

have fun!

[njloof]

I'm putting a HUGE effort in NOT trying to order at least a single 7s3p pack to
rewire as a 18s1p for my e-pocketbike that would really shine with 20Ah and 68v.

I'll let you know how it goes I figure it's the best way to get to know these batteries on a small scale first.

[zEEz]

I'll let you know how it goes

yeye ... so then I can let the dark side to interface to the paypal account

[JRP3]

It sounds like he is comparing them to some other product he is using/promoting (green energy 12v?).

I think that's just a reference to some experimenting he's been doing on A123 pouch cells, casting them in a plastic block.

I was suprised to see this guy "bottom balancing" since it is widely regarded as ineffective and bad for cells.

If done correctly there is no reason it should be bad, just as if done correctly top balancing should not be bad. Remember, "top balancing" means you are unbalanced at the bottom. I've run my pack of 100ah CALB cells bottom balanced with no BMS for the last three years, including driving my car till it stopped once, with no issues. In that case bottom balancing saved my cells.

He keeps talking about how the cells run cool at a 45a, but this is only a 0.75c discharge so I don't see that as a relevant data point; I already know that in small ebike packs at 6c I don't have a heat issue, but I am curious how this will hold up at 10c in a 300 cell pack. He also mentions how the typical Electric car pulls 100a-150a - which strikes me as odd, I see higher continous discharge at 165v on my 480lb Vectrix motorcycle and my VW bus conversion. Maybe he is talking about slow speeds, or high voltage with 384v AC systems, KW would have been a more useful metric.

10C on a 3P pack is 600 amps, how long do you think you'll be pulling that type of current? 180 amps is only 3C for a 3P pack, I wouldn't expect a reasonably efficient vehicle to pull much more than that on average. Jack's cars are small Porsche kit cars so they are fairly efficient.

[deVries]

I think it will be pretty easy to dremel off the "Buss Bars", open the case, and extract the cells, but I had a tough time working with the short tabs, maybe you will do better. ... Yes, one cannot solder the tabs of these cells, and tig would heat-damage the cells, but I have posted a thread on spot-welding the tabs that is effective.

So, according to Oatnet spot welding should be an option to use at least to replace a bad cell. I'm wondering if there might be some way to "spot weld" or connect the bus bars back together using a replacement cell in between? Could the bus bar be scratched/roughed up to accept some type of special formula solder, many types of solder available, or just spot weld it back to the bus bar, or sandwich the tab with copper/aluminum strip and mechanically attach that strip to the bus bar or spot weld or solder it?

I didn't realize that folks here were planning on harvesting the cells from them instead of using them intact in the modules.

Very few will attempt that, cut every cell apart, though maybe cutting out three 7s1p strings would work & still be very useful to do that. For instance, make a 21s1p battery from one module. But, we don't know if that can be done yet.

7s3p modules can be used for an eBike (1 w/RC motor @ 25v, 2 @ 50v, or maybe 3 @ 75v but "heavy") or definitely for a Motorcycle. Luke's hottest eBike ever used 40-60Ah when you convert it back to 50v. (Still waiting for the 1/4 mile run Luke to lock-down those highest speed numbers. You know you want to & we do too. )

Sooo, yeah, the fastest eBike setup used similar 1-module+ but less than 2-modules capacity-power levels, but with lighter weight Nano LiPo at higher volts & lower Ah ... so cells are just in a different configuration.

It has 30s 45c nanos now.

I got new special firmware that allows 120v.

[oatnet]

though maybe cutting out three 7s1p strings would work & still be very useful to do that. For instance, make a 21s1p battery from one module. But, we don't know if that can be done yet.

Sorry I don't think that can be done. Since the cells are paralleled by (3), and the parallel groups put into series, you can't cut out a 7s1p string... at best you could cut out (7) 3p blocks. The only way to get a 1p string from this is to cut all the tabs at the bus bar. That leaves you with really short tabs, which I have found very difficult to work with.

People have built packs with short tabs, and no tabs (dremel off the pouch material), but it will definitely take a whole lot more time, and you could find yourself spending more on a solution to overcome the lack of tabs than you saved buying a pack instead of cells. Plus the individual cells I got from Victpower are new and pristine, and Rickard said in the video that the cells he got were used. The only reason I am getting packs is because the packaging is perfect for a car conversion.

If done correctly there is no reason it should be bad, just as if done correctly top balancing should not be bad. Remember, "top balancing" means you are unbalanced at the bottom. I've run my pack of 100ah CALB cells bottom balanced with no BMS for the last three years, including driving my car till it stopped once, with no issues. In that case bottom balancing saved my cells.

Whether you top or bottom balance, the weakest cell determines how much capacity you can take out of the pack. However, the lower the DOD, the more impact to the cell's cycle life. Top balancing runs to a higher DOD, so the cells are less impacted. Regularly discharging the cells to a bottom balance means you are regularly reducing cycle life. In addition, a properly sized automotive pack should have headroom that you rarely, if ever, hit that 80%DOD mark. Ebikes are different - we can pedal them if we run out of juice, but a car needs spare range.

When you say "driving my car till it stopped", I assume you are saying that you discharged your pack far enough to hit your controller's LVC, and it was easier to trip because all of your cells were low. The exact same effect could be achieved with top balancing, and setting a higher LVC, without reducing your pack's cycle life, and catch the weak cell even earlier. However, the fact that you lost focus long enough to let the pack discharge that low indicates you may be a good candidate for using a BMS. I also run without BMS, but I seemed to be much more attuned to monitoring pack voltage than some other folks, I've spotted troubled cells when my voltage was low at 20%DOD.

I think that's just a reference to some experimenting he's been doing on A123 pouch cells, casting them in a plastic block.

At first blush that sounds like a heavy, cell-killing heat trap but maybe they are liquid cooled... I'll have to go read more.

-JD

[JRP3]

Whether you top or bottom balance, the weakest cell determines how much capacity you can take out of the pack. However, the lower the DOD, the more impact to the cell's cycle life. Top balancing runs to a higher DOD, so the cells are less impacted.

I think you meant higher SOC, but that does not have "less" impact on the cells. Holding a cell at a higher voltage for longer periods can cause the electrolyte to breakdown faster, that's why when storing cells it's recommended to do so around 50% SOC or less. Higher voltages cause electrolyte instability. Ideally cells would be cycled in their middle SOC range, A123 testing has shown cycling in the tens of thousands when cycled between the middle range of SOC.

Regularly discharging the cells to a bottom balance means you are regularly reducing cycle life.

Who says it's a regular occurrence? Since the initial bottom balance when assembling the pack I've only done it one other time in three years just as a check, it didn't really need it.

In addition, a properly sized automotive pack should have headroom that you rarely, if ever, hit that 80%DOD mark.

Indeed, and not only do I rarely hit 80% DOD I also avoid charging above 90% or so most of the time, prolonging cell life.

When you say "driving my car till it stopped", I assume you are saying that you discharged your pack far enough to hit your controller's LVC, and it was easier to trip because all of your cells were low.

Yes.

The exact same effect could be achieved with top balancing, and setting a higher LVC, without reducing your pack's cycle life, and catch the weak cell even earlier.

As described above I don't think I've reduced my pack life, and by spending less time at a high SOC I'm probably extending it.

However, the fact that you lost focus long enough to let the pack discharge that low indicates you may be a good candidate for using a BMS.

No loss of focus, I wanted to see what happened, and knew with a bottom balanced pack I would not be driving any single cell to zero. As I said, I've gone three years with no BMS and no problems.

[JRP3]

At first blush that sounds like a heavy, cell-killing heat trap but maybe they are liquid cooled... I'll have to go read more.

-JD

It seemed like a bad idea to me, no liquid cooling, just casting them into a block of plastic. He was trying to create a TS type prismatic format. Paralleling a bunch of cells into a 120 ah brick at low C rates probably wouldn't cause heat issues, but you do miss out on some of the high C rate capabilities of the A123 cells.

[oatnet]

Regularly discharging the cells to a bottom balance means you are regularly reducing cycle life.

Who says it's a regular occurrence? Since the initial bottom balance when assembling the pack I've only done it one other time in three years just as a check, it didn't really need it.

So you aren't really bottom balancing, you did it once in 3 years. Oh My. I hate to tell you, but large format cells in general, and CALB or Tsky or Sky Energy cells in specific, have great variations in self-discharge rate, which means a few of your cells are likely way out of balance at this point.

Anyhow, you have some unusual opinions, and we're taking this thread off topic on a an issue that has been pretty well hashed out on the sphere, so I am not going to reply to posts about bottom balancing in this thread any more, please start a new one (or add to an old one) if you want to discuss it further.

-JD

[HumboldtRc]

I just got my 2 7s3p A123 modules!

They are clearly used/rejects. The 2 I got are different. One is off-white and one is black. They both read 23.11 volts at the terminals. There is a big dent in the black one, also the heat-sink plates looks thiner on the black one. The white one is not square, it was put together wrong, the whole pack leans.