Best battery?

[dimitrib90]

What is the best battery that will allow me to have a very big capacity of 4KWh with a weight of less than 90lbs? I need about 72V with a massive 60 amps. I was thinking about using A123 cells because of their power to weight ratio. Can someone help me with this massive project. Thanks

 

[johnrobholmes]

Lithium Polymer would get you there, but be one huge dangerous chunk. a123 or PSI cells would be my second instinct. PSI cells in a 24s6p would be 115lbs before wires and have 4,752 kwh of energy assuming 3.3v/cell nominal. a123 should weigh more since it has a higher discharge rate.

 

[Ypedal]

Welcome to the forum !!

And how about telling us a bit more about the project, sounds like a bit too much battery for an ebike( for some.. Dr.Bass on here might not agree ) .. car? EV motorcycle ?

Motor ? Controller specs ? Weight and performance expectations ?

 

[dimitrib90]

Actually its for an electric motorcycle. There arent too many forums that are as good as this forum so I decided to join es. Wouldnt A123 cells be lighter? I need 4KWh which means 20s27p of A123 cells. Thats 540 cells. 10 cells weight 1.6 lbs which is 86 pounds not including wires etc.

Edit add: Is there anything that would be lighter? Price is also an option. It cant cost more than 3000.

 

[johnrobholmes]

Just did the math, and it looks like the a123 Watt/hour to Watt/hour is indeed lighter than PSI cells. That doesn't make much sense because of the discharge rates, but maybe a123 really does have something unique in their chemistry.

And if you get a steal of a deal on a123 at $12 each that is over $6,000. You can't have lightweight power for cheap, just not gonna happen.

 

[ZapPat]

Actually its for an electric motorcycle. There arent too many forums that are as good as this forum so I decided to join es. Wouldnt A123 cells be lighter? I need 4KWh which means 20s27p of A123 cells. Thats 540 cells. 10 cells weight 1.6 lbs which is 86 pounds not including wires etc.

Edit add: Is there anything that would be lighter? Price is also an option. It cant cost more than 3000.

It all depends on you desired continous and peak discharge rates. Of course at 3000$ for 4kWh you don't have many choices. Maybe a good option here would be the new headway cells, but you will also pop your 90lb limit for sure using these, and we still don't have more than one report of the new and improved cells and QC. Ping batteries are quite light and cheap, but are only 2C continous, so could not output more than 8kW continous.
Pings specs are: 48v20ah, 150x150x270mm, 10.5kg
The new headway cells are bulkier than their old ones I believe, but they are suppost to be rated at 5C continous or something.

 

[matt_in_mtl]

I need about 72V with a massive 60 amps.

Ping batteries are quite light and cheap, but are only 2C continous, so could not output more than 8kW continous.
Pings specs are: 48v20ah, 150x150x270mm, 10.5kg

just to state the obvious 60A at 72V is only 4.3kW, well within the limits of a Ping pack. Of course if 60A is your expected average consumption, your peak requirements will be much higher than 8kW. 4kW isn't much of a peak power for a motorcycle, so I suspect it is your average expected power requirement?

 

[Ypedal]

I suspect a typo..60ah capacity requirement ? lol..

 

[silicium]

The best battery ?
A123 for sure...
but, DIY pack...

 

[Patrick]

I have to agree; I don't think you'll be able to meet all the requirements of capacity, weight and cost. The larger prismatic cells come close in varying degrees. ThunderSky in 40 Ah works, but is only 2.8 kWh. 60 Ah is good, but weighs in a little heavy. Both are 3C rated, for 120 and 180 amps continuous, respectively. High Power might fit in the 50 Ah size, meets cost easily, but is only 2C rated. You haven't specified what peak currents you'll need.

So, yes, some compromise will be needed. The essence of engineering . . .

 

[GGoodrum]

I think you are right, it is supposed to be 60Ah capacity, as 60A for a motorcycle application is not what I would call "massive".

Also, for a 72V setup, you need to think in terms of 24 in series, not 20. DeWalt marketing hype lists these as 36V, but in reality, they are more like 33V nominal. Using 22 in series would get you close to the 72V nominal figure but not for charging. Because of the fact that SLAs have a much wider difference between what the cells are charged to, vs the "nominal" voltage they end up at, a better match for replacing SLAs with LiFePO4-based packs is to use 4 LiFePO4 cells for every 6 SLA cells. So, a 72V SLA setup would have 36 cells (6 x 6 cells in each 12V battery...), and so to replace this with LiFePO4 you would use 24 cells in series. One of the performance advatages in doing it this way is that if the electronics are setup for a 72V SLA setup, thay have to be able to handle the voltage of the packs right off the charger, which is about 87-88V (2.40-2.45V per cell...). A 24s LiFePO4 pack would get optimally charged to 87.6V (3.65V per cell...), so it can be a "drop-in" replacement. The performance "boost" comes in the fact that once the packs are loaded up a bit, and the surface charge is burned off, the SLA voltage will drop to around 72V, but the LiFePO4 voltage only drops to about 80V.

 

[Battboy]

Here is a little 60V / 60 Ah Custom Designed Motorcycle Battery I designed. It might give you some valuable information as it is done in real scale and based on the LiFeBATT 40138 Cells. Should help you think about your particular configuration. The Battery Weight would be 87 lbs. Battery box would be a DIY project for sure. Cell cost approx. $ 3,000.00.

Best Regards,
Don Harmon



View attachment 60V_60Ah Motorcycle_2.jpg

 

[dimitrib90]

The reason I said "massive" is because I have yet to see a 4kwh battery on an ebike forum.(Not even Docs battery is 4kwh) Thank you for all the support and opinions. I can get A123 cells for about $7 a cell from an inside source. I think Im going to go with A123 cells and see how its going to work out from there. Thanks again. My next question is motor. Does this etek rt motor seem like a good efficient motor that will allow me to go 100 miles on my 4kwh battery at 65mph? http://www.electricmotorsport.com/store/ems_ev_parts_motors_etek-r.php

 

[dimitrib90]

Don, I did the math and to get 72V at 60 amps, it would come out to 108lbs and a little bit more than 3500. Thanks for your help though. I appreciate it.

 

[MitchJi]

I can get A123 cells for about $7 a cell from an inside source. I think Im going to go with A123 cells and see how its going to work out from there.

Hi,

At $7 each its a no-brainer. You could probably sell enough cells on the forum at $9 each to fund your pack.

 

[Battboy]

I agree - why even bother if you can get A123 Cells for $ 7.00 ea. What a "no brainer" for sure. I bet everyone would love to have an inside connection like you do!

Don

 

[ejonesss]

me too.

I agree - why even bother if you can get A123 Cells for $ 7.00 ea. What a "no brainer" for sure. I bet everyone would love to have an inside connection like you do!

Don

 

[dimitrib90]

I have a really good friend and Im going to leave it at that. Has anyone heard of the new A123 32cells?

Edit add: Does anyone on this forum live in the bay area? I would like to setup a big project or something. I think it would be kinda fun.

 

[johnrobholmes]

I haven't heard of em. Are they bigger ones?


$7 each, yeah, there is no decision to make :lol:

 

[MitchJi]

Hi,

I have a really good friend and Im going to leave it at that. Has anyone heard of the new A123 32cells?

Edit add: Does anyone on this forum live in the bay area? I would like to setup a big project or something. I think it would be kinda fun.

I haven't heard of em. Are they bigger ones?

These are the newer cells:
http://www.a123systems.com/#/products/p3

32 Series Automotive Class Lithium Ionâ„¢ Cells: A123Systems recognizes that the impending transportation revolution requires industry-specific solutions. To that end, we have developed two Automotive Class Lithium Ion cells, the high power AHR32113M1Ultra and the more energy dense AHR32157M1HD.

These two cells, designed for HEV and PHEV applications offer very low cost per Watt and Watt-hour, respectively.

The AHR32113 uses the new Ultra electrode design, offering yet higher power over that seen in the traditional ANR26650M1.

Alternatively, the 32157 uses a more energy dense electrode, geared for the higher energy requirements of the PHEV marketplace, while not sacrificing the power capability needed for charge-sustaining operation.

Full specifications may be available under NDA.

They have been on the A123 site for at least four months. I'm pretty sure they are not in production (clicking on developers kit gets you to the old cells [$18 each] and an NDA is required for specifications). They look like sweet cells however. Larger form factor, threaded ends, higher energy density (the higher energy model probably has sufficient power [15c or 20c?]) and possibly lower cost in mass production.

Quite a few members live in the S.F. Bay Area myself included. You can send me a pm if you want. I'm pretty sure if the project involves access to $7 A123 cells there will be quite a few people interested in participating.

 

[Battboy]

No specs. without and NDA ??? What are they not telling us ?

Don

 

[ohyea]

how many ah are these new a123 cells? are they avail?

 

[swbluto]

I can get A123 cells for about $7 a cell from an inside source. I think Im going to go with A123 cells and see how its going to work out from there.

Hi,

At $7 each its a no-brainer. You could probably sell enough cells on the forum at $9 each to fund your pack.

Where demand raises, so does price...

(Let's hope it's a well-nourished source he's willing to share in some form.)

 

[dimitrib90]

I can get A123 cells for about $7 a cell from an inside source. I think Im going to go with A123 cells and see how its going to work out from there.

Hi,

At $7 each its a no-brainer. You could probably sell enough cells on the forum at $9 each to fund your pack.

Where demand raises, so does price...

(Let's hope it's a well-nourished source he's willing to share in some form.)

Sharing? Sorry I cant. But extras is a different story. If I have extras, I will be selling them at around $13 a cell shipped.

 

[dimitrib90]

I just found out that in order to get each cell at $7, I need to buy around 2000 cells!!! I dont have the money nor the time to fool around with 2000 cells.