[asulil]

I came across this article that proves teslas cost for batteries are around $180kwh. why do I hear commonly that our batteries cost about $14k to $20K or more than 3x cost $/kwh?

see: http://www.greencarreports.com/news...a-tesla-model-s-battery--and-what-it-may-cost

and this thread over at Teslas forum is a MUST read also shows that the battery cost less than $200 Kwh - it shows that a 89kwh battery cost about $14,000, with more than three times the capacity of our battery - i just don't see why our battery pack cost that much.

http://www.teslamotorsclub.com/showthread.php/17590-Model-S-Battery-Pack-Cost-Per-kWh-Estimate

maybe someone should make a battery pack for the Karma using the panasonic cells.

 

[doug]

The 18650 form factor cells that Tesla uses benefit from economies of scale that the A123 cells are unlikely to achieve. The A123 cells do have a power density advantage which is useful in a hybrid like application. Tesla's solution is to have battery pack with so much energy, that there is plenty of power even if the power density is relatively low.

 

[smoothoperator]

ACP was the first to use the 18650 and this is where Tesla initially got the idea for an ESS using the 18650 cells. Tesla really pushes the thermal envelope on these batteries.

The active cooling target is 55 C on the Model S, power output is limited on the Karma at 50 C. Passive cooling is also about a 10 C difference. Long of the short is the batteries run at much greater temp extremes in Tesla vehicles than the Karma. The Model S batteries also tend to heat up quicker than the nano-phosphate batteries in the Karma.

There are about 16 modules with voltage being 4.05v on the Model S.

Having a tier 1 battery manufacturer in house will reduce the $/kwh and will allow for cutting edge battery technology to used in future Fisker vehicles. A123 also manufacturers 18650 and other variant type cells and this could easily be utilized in future vehicles. Tesla right now is looking to diversify their battery supply chain in the short term (Samsung) with a mega-factory jv as the ultimate solution. Right now they are 100% dependent on Panasonic. With regards to ESS supply chain interruptions Fisker currently is better positioned than Tesla in that they will never have to be dependent on a third party supplier for ESS'.

IMO I think the 18650 form factor ESS' are nearing end of life. Tesla has even hinted that they are not wedded to the form factor. With battery costs coming down across the board I think it makes more sense to partner with a cutting edge company that is pushing the limits of auto-grade engineered ESS' vs 18650 cells. If you have that capability in house that is the best of all worlds.

 

[SoCalGuy]

Ultimately the right solution is probably a 'hybrid' battery - a mix of high power cells with high density cells. Consider a pack comprised of high power 5 kwh of A123 cells (or even supercaps) coupled with an additional 25 kwh of lighter, more energy dense (and cycle sensitive) 18650 cells. You would get the energy density and weight savings of the Tesla configuration with the power of the A123 cells. Think about it - the only time you need 'high power' application is on acceleration - the A123s are capable of burst discharges of 50C and sustained discharge of 10C - fantastic for acceleration (and also great in receiving regen braking energy). The Tesla battery supports bursts of 8C and sustained in the 3-5C range I believe and is more fickle with respect to charge/discharge cycles (Doug/Smooth correct me here).

 

[smoothoperator]

Ultimately the right solution is probably a 'hybrid' battery - a mix of high power cells with high density cells. Consider a pack comprised of high power 5 kwh of A123 cells (or even supercaps) coupled with an additional 25 kwh of lighter, more energy dense (and cycle sensitive) 18650 cells. You would get the energy density and weight savings of the Tesla configuration with the power of the A123 cells. Think about it - the only time you need 'high power' application is on acceleration - the A123s are capable of burst discharges of 50C and sustained discharge of 10C - fantastic for acceleration (and also great in receiving regen braking energy). The Tesla battery supports bursts of 8C and sustained in the 3-5C range I believe and is more fickle with respect to charge/discharge cycles (Doug/Smooth correct me here).

I think around 4C max for the Performance version. The larger the battery the less the C rate generally speaking. If A123 made a 85kwh pack the C rate would be close to what the Model S' is. IMO I think it only makes sense to do the 18650 cells for >40kwh packs. The amount of thermal management required is significant.

 

[msajidkhan]

It may be a dumb but I have to ask. How much it cost to charge up the full karma battery at home ? Any idea ? $4.00 ?

 

[SoCalGuy]

It may be a dumb but I have to ask. How much it cost to charge up the full karma battery at home ? Any idea ? $4.00 ?

Depends on your utility rates, which can range in the US anywhere from $0.09 to $0.38 +/- depending on where you live and what your metering plan is (For a rough idea, check out this site: http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a )

To fill up the 20 kwh in the Karma's "electron tank," that translates into $1.80 to $7.60 (for those that live in Hawaii). For most of the US, it will be around $2.40 ($0.12 per kwh).

 

[msajidkhan]

Thanks SoCalGuy. I am in Arizona so it's about 11 cents. I guess it's not as bad as I thought. I am getting 25 miles on a full charge battery... So basically what fisker mentioned on their website is true. i.e $.08 a mile....

 

[SoCalGuy]

Thanks SoCalGuy. I am in Arizona so it's about 11 cents. I guess it's not as bad as I thought. I am getting 25 miles on a full charge battery... So basically what fisker mentioned on their website is true. i.e $.08 a mile....

25 miles on a full charge? Are you in a particularly hilly or very cold area? In SoCal, I routinely get between 35-42 miles depending on conditions (area where I am has a number of hills).

 

[msajidkhan]

Full charge per miles

25 miles on a full charge? Are you in a particularly hilly or very cold area? In SoCal, I routinely get between 35-42 miles depending on conditions (area where I am has a number of hills).

I am in Phoenix AZ. It's a very hot area and no hills. My commute is about 10 miles daily and when I get back home, I am left with 32 miles on the charge. When in the morning I get out of the house, I lose 1 miles instantly so I start my day with 49 miles on a the charge. My commute is not straightforward. I hit lot of red lights and then I also drop off my little one at school and wait there for about a minute. Do you suspect an issue with my battery ? Couple days ago, my engine light was turned on and then it was gone.. Since then no engine light....

 

[SoCalGuy]

I am in Phoenix AZ. It's a very hot area and no hills. My commute is about 10 miles daily and when I get back home, I am left with 32 miles on the charge. When in the morning I get out of the house, I lose 1 miles instantly so I start my day with 49 miles on a the charge. My commute is not straightforward. I hit lot of red lights and then I also drop off my little one at school and wait there for about a minute. Do you suspect an issue with my battery ? Couple days ago, my engine light was turned on and then it was gone.. Since then no engine light....

If you run the AC hard during your daily commute, that might explain some of the reduced range. Freeway cruising around 70-80mph I usually get around 35 miles, and flat, around town driving in LA I get 40 +/- depending on stop lights, parking etc.

 

[msajidkhan]

Ok, well I may have some issue with the battery. Do you recommed anyone who could take a quick look at my car battery and make sure everything is ok ?

 

[SoCalGuy]

Ok, well I may have some issue with the battery. Do you recommed anyone who could take a quick look at my car battery and make sure everything is ok ?

Not necessarily a bad battery - but I'll leave that to Harleyguy and Lormax to opine on.