A123 Prismatic cell pouches (10/20Ah)

[daniel.weck]

It looks like some folks on the German Pedelec forum are onto a group buy again

A123 15Ah und 20Ah Zellen - Pedelec-Forum

The Wh per Kg seems higher than LiFePo4, with a higher C discharge rate !

Anyone on here with more information ?

Cheers, Daniel

 

[winterdog]

are the prismatic cells some thing new and juicy
this report made me pee my self (just a little)

 

[Fecn]

prismatic refers to the shape of the cell... They're the square pouch ones (as opposed to cylindrical) - They're nothing particularly special apart from the fact that A123 only did Cylindrical cells before (very good quality ones I might add). With prismatic cells, you get a higher energy density because the cells can be packed more neatly with no gaps in-between, but you get lower peak currents because of the way the electrodes within the cells are arranged.

 

[emissions-free]

Yeah I know about them

I've got a sample order on their way to me right now and if they meet the specs I'll have a batch of them.

They'll be competitively priced and put into assembled packs with a proper case, charger, as high a rated BMS as you require (80A cont is no problem). Just cells is possible but I'm much happier doing a proper job to be honest.

However these are not cheap cells and although they have really amazing specs, they are more than most people will ever need. A single 20Ah cells can output over 2500W and a 36V 12 series 20Ah pack can output 600A and about 30,000W, for 2mins

The power density is more than 5KW per kilo. The energy density is 123.75whrs/kg for the 15Ah and 137.5whrs/kg for the 20Ah. These figures are far better than any other available LiFePO4 and comparable to Li Po but without the asociated hazards or the short cycle life, plus it's not cheap. They also claim to have a cycle life of 10-15 years.... Too good to be true? Well the previous A123 cells delivered, so there's no reason to believe that these will not do the same after 3 years of further development. Here's some sizes and weights and don't forget these are 3.3V nominal and not 3.2V like standard LiFePO4.

Model: AHP 70165227 Model: AHP 68150211
Capacity: 20Ah Capacity: 15Ah
Size: 7.0X 166X227mm Size: 6.8X 150X211mm
Weight: 480g Weight: 400g


Once I have the sample cells I'll try to get them tested ASAP. I've ordered the parts to make a resistive load made up of 20 * 0.1ohm 150W resistors that will be switched in as required to confirm the 450A and 600A output of the 15Ah and 20Ah cells respectively. Battery analysers that can accept 600A are rather expensive so this will have to do for the C rating aspect of the tests. They will also be independently analysed with computerised battery analysis system.

I'm rather excited

 

[winterdog]

Yeah I know about them

I've got a sample order on their way to me right now and if they meet the specs I'll have a batch of them.

They'll be competitively priced and put into assembled packs with a proper case, charger, as high a rated BMS as you require (80A cont is no problem). Just cells is possible but I'm much happier doing a proper job to be honest.

However these are not cheap cells and although they have really amazing specs, they are more than most people will ever need. A single 20Ah cells can output over 2500W and a 36V 12 series 20Ah pack can output 600A and about 30,000W, for 2mins

The power density is more than 5KW per kilo. The energy density is 123.75whrs/kg for the 15Ah and 137.5whrs/kg for the 20Ah. These figures are far better than any other available LiFePO4 and comparable to Li Po but without the asociated hazards or the short cycle life, plus it's not cheap. They also claim to have a cycle life of 10-15 years.... Too good to be true? Well the previous A123 cells delivered, so there's no reason to believe that these will not do the same after 3 years of further development. Here's some sizes and weights and don't forget these are 3.3V nominal and not 3.2V like standard LiFePO4.

Model: AHP 70165227 Model: AHP 68150211
Capacity: 20Ah Capacity: 15Ah
Size: 7.0X 166X227mm Size: 6.8X 150X211mm
Weight: 480g Weight: 400g


Once I have the sample cells I'll try to get them tested ASAP. I've ordered the parts to make a resistive load made up of 20 * 0.1ohm 150W resistors that will be switched in as required to confirm the 450A and 600A output of the 15Ah and 20Ah cells respectively. Battery analysers that can accept 600A are rather expensive so this will have to do for the C rating aspect of the tests. They will also be independently analysed with computerised battery analysis system.

I'm rather excited

looking fwd to your results

do you have any info on how you would package these

 

[emissions-free]

Sorry it still early days as the first samples have only just become available and whilst I have thought about the case a little, there's still lots to do in the meantime. I was thinking that a 36V and 48V pack would be more than enough for anyone but it seems that isn't enough for some

A 36V 15Ah pack will come in at only 4.8kgs of cells. A 36V 20Ah, is just under 6kgs. You can see the sizes above so it would just be a matter of deciding whether to go for 2 lots of 6 approx 42mm high, or a single stack of 12, approx 82mm high. A shrink wrap pack is definitely no problem, the case may need a little work as the size of the cells is a bit wider than a typical slide on case so might need something custom made. Not necessarily hugely expensive but more than a mass produced unit for sure.

They're not the most convenient size for an e bike. I'd prefer them a bit narrower and longer and maybe a little thinner, but that's just being picky

I should have the samples Monday and have the load to test 1 to 600A on Friday (I'll have to get onto them this week to try and make sure it's ready). Will keep you informed on how it all pans out.

 

[daniel.weck]

Although I'm sure that some of the UK-Pedelecs forum crowd would be interested in early-adopting such technology, this kind of high discharge rate seems to suit the needs of the Endless-Sphere folks even better, as they love high-powered e-bikes/mopeds.

Personally I'm more interested in the small form factor achievable with A123 cylindrical cells in a low Ah battery pack (4Ah -> 8Ah), but of course that's because I already use a long-life 10Ah LiFePo4 which suits me well (400W 12A peak at the moment on my 36V Bafang).

Still, there's a lot of potential for these prismatic pouch cells, especially if coupled to a good BMS

Looking forward to hearing more about the performance / price ratio !

Cheers, Daniel

 

[NRG]

I'll be interested in the results for reliability and life but not the discharge rates because as Daniel says C30 discharge rates are for the ES guys, you don't need much more than C3 on a 'normal' E-Bike. I'm using C20 Lipos and I get nowhere near those discharge rates, the power density to weight ratio is of more interest. Still, if these prove to be as good as they look then it will be a major step forward....

 

[emissions-free]

I agree guys, these are not for everyone.

I'll let you know how I get on and ty to give you some idea of firm pricing within about 10 days or so (hopefully sooner), after I've done some testing and the order is in my hands.

I wll say that the pricing for cells will be around the level of high discharge Li Po RC from China when compared to the Whrs or maybe a little higher. They will not be stupid money.

 

[daniel.weck]

Battery porn here (if you have an Endless Sphere account):

Endless-sphere.com • View topic - 2.5USD per Ah for 15Ah and 20Ah 30C cells