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Replacing the Model S battery pack

With the battery pack being the base on which the rest of the car is built on, is it even possible to replace the battery pack when it comes to the end of its useful life?

Tesla indicated in their FAQ that they cannot forecast cost of replacing battery because battery technology is changing but I see no information on how easy or hard or if it is even possible to replace the battery pack.

The forum is large and it is difficult to search if someone may have already posted this question so if this is redundant, apologies up front.

Yes, the battery is designed to be easily replaceable. It is simply bolted on to the bottom of the car and there are quick connect hoses that can be disconnected fairly easily for the fluid lines.

The thought is the battery pack could be swapped out at a Tesla Service center in under 30 minutes. It might even be faster than that with some talk of it being in under 5 minutes with the right equipment. It's the kind of service that would not damage or harm the car or require any major intrusion into the car structure.

So the battery is easy to replace. The cost of the replacement is an unknown as you stated, but the battery technology keeps improving every year and the cost per unit of energy storage should keep coming down, so the cost of a battery pack today compared to the future cost should be less or the other alternative is you pay a similar amount, but get a battery that could have double or triple the range of the same cost battery today. Tesla has stated that the actual improvement in energy storage over the next couple of years should average out to about 8-10% a year.

There could even be the possibility of a resale market for used battery packs which could help offset the cost of replacement. That's pure speculation on my part, but when a battery is not effective for automotive purposes, it still has plenty of capacity and ability to deliver power, so I would think there would be some secondary market that would develop for used Tesla battery packs in the future.

I'm going to guess that there will be a trade-in value of some sort for a depleted battery pack. Even if not used for power storage, it would have materials inside that would have some salvage value, at least.

Thinking outside the box, it would be an interesting side business for someone or Tesla to have locations, perhaps at the Super Charging spots, where you could pull in, have your battery swapped out in 5-10 minutes, and get back out on the highway toward your next pit stop. This would be like an ICE car filling up at a gas station and leaving. Granted the devil would be in the details, but something like temporarily renting a battery pack and then on your return trip you could revisit the rental location to pick up your personally owned battery, which they would have fully charged by then, for getting back to home base.


There have been threads on this before. I assume VolkerBerlin will provide them :)

I'd like to take several used batteries and gang them up for power storage at my home.

Think about this:

Charge the batteries at night when electricity is cheap and use the electricity from the batteries during the day when power is more expensive.

I typically use about 800KWHr per month (or 27KWhr per day). One 85KWHr battery with half its life remaining would be more than enough for me.

If someone has a PV system (solar), they could TOTALLY live off the grid by storing solar energy in the battery for use during the time when there is no sun power available.

I have seen an interview in which Wlon claims that the battery cn be changed in under a minute af the the model S is positioned on top of the change machine. I believe they had a clip of the machine doing just that.

Sorry--small keyboard: "Elon" "can" "in" make more sense.

In its final recycle, a TM battery's lithium is almost entirely recovered. There are some other materials worth recovering, but nothing pricey or exotic.

So far, the only business model that makes any sense is if the batteries are all owned by the rental or manufacturing co. from the outset. There may be a way to partially finesse that, but nobody's laid it out persuasively yet.

I have seen an interview in which Wlon claims that the battery cn be changed in under a minute af the the model S is positioned on top of the change machine. I believe they had a clip of the machine doing just that. (Dr. Bob Reinke)

Almost, but not quite.

@dahtye, do you have some error in that consumption? I use around 2000kWh of electricity in entire year (and could use a lot less if I would pay attention to it). That's ~167kWh / month. What takes that huge amount of energy in your house?

@Timo: 167kWh is *really* low for a month. My HVAC system in the summer can use up over 4000 kWh in a month if it's really hot.

Although it might seem like a neat idea to use Lithium Ion batteries for energy storage, I think most folks who implement such a setup are using lead acid deep-cycle units. Lithium ion cells are pretty picky about how they're charged and based on my readings may not tolerate or be ideal for that kind of input/output.

So does this mean you could buy the 40kwh model S today and in a few years if your needs change, have it swapped out for the 85kwh battery or whatever is available at the time?

@timdorr: do you live in Hades?

@valdezs1: In my understanding, yes. But be aware that you'd never be able to use the supercharger network if your original vehicle were built with the 40kwh pack. The internal wiring and connections are not designed for it.

Although battery replacement cost is unknown for the Panasonic 18650 Li ion 3100mAh cells, they seem to be pricey individually. $14 for 1, 10 for $100 was cheapest I found. 60kWh model 5,000 approx cells x $10=$50,000 Yikes. Of course the 2% ownership Panasonic has in Tesla has no doubt lowered the unit cost substantially, hopefully down to $3@ cell x 5,000=$15,000. These are only speculation not factual.

My guess is that battery replacement may not be necessary for perhaps 12-15 years depending on the tipping point of a given owner on range miles left on the aging battery. Future battery cost will likely be lower for same range we get today or same cost as today for increased range. Whatever the replacement cost is established at, it will have to be reasonable for it to be feasible for consumers in the market place.

There are about 7K cells in the battery, haven't seen differing counts for different size batteries, tho' it makes sense.

@Timo: 5.5 kWh per day? You must have gas or solar hot water, cooking and heating. That is an extremely low usage for a normal house.

First post here - P85 reservation holder. Way down the list but nevertheless very excited and can't wait to get this car.

@Timo: We own a 5,000 sqft home in the Phoenix area with solar panels on the roof. We consume on average 90kwhs daily - almost all of it is generated by our solar panels - we pay about $100 per year for electricity - almost all of that is for admin. charges. We also generate hot water with our 2 solar heaters.

We run 4 AC units during the hot summer months.

Unless you live in a tiny apartment I just can't see how you could get away with such little electric power. Are you sure your numbers are correct?

Brian H:
I think the 7K cells you are referring to is for the 85kWh model. I purchased the 60kWh model due Nov/Dec which I think has the fewer 5K cells since all 3 models utilize the same Panasonic 18650 Li ion cells.

I look forward to future years bringing battery costs down and increased range. Most folks I talk to are pleasantly surprised about how long of range the current Tesla models / batteries will do.

SolarCity (an Elon sponsered company) could use old packs in their future solar installations in five years.

@GeorgeA - do you have confirmation about the 18650 cells? The original story was that the 40kWh model uses different cell material to the other two.

@Carefree, yes my numbers are correct. Heating (no need for AC) is done via district heating (only couple of months needed for air, water is for all times). City dweller, so house is quite a bit smaller. Not tiny though, at least if you look at what I could get by selling this one (perfect spot in the heart of the city).

I'm guessing water and (probably inefficient) AC are the reasons why you people seem to have huge electricity consumption compared to me.

Just for fun, there are zero consumption houses even in my latitude. It's all about insulation, not letting heat to escape, and vice versa.

Wow! That's incredible - good for you.

It really would not work in the desert. We have 110 degree weather from May through September. I am just thankful for our solar panels which supply enough power for all our electricity needs and the solar hot water heaters.

nickjhowe:"Do you have confirmation about the 18650 cells? The original story was that the 40kWh model uses different cell material to the other two."

I do not have confirmation about the 40 kWh version. You may indeed be correct since now that you mention it, I do recall reading a while back that this model may have a different battery configuration than the other two models. Perhaps a Tesla team member could clarify this for us.

I am still impressed that Tesla research team determined that lots of these small individual Li ion cells along with liquid cooling system would be more efficient to utilize to obtain these long range mileage numbers 160, 230, 300 than employing the use of 1 large monolithic battery.

@Timo: the bulk of my power costs are for heating, with hot water second and running the oven for cooking third.

Don't underestimate the savings to you by district heating, and combining everything in an energy efficient block of small units.

Putting solar hot water on my house cut the electricity used for it by around 50-70%. If we had the option for gas backup instead of the off-peak electric then I'd use that. Relying on bottled gas isn't a good option for hot water as its too expensive.

Things like refrigerators also use quite a lot of power. If you have someone at home most of the time (I do) then you notice the increase in power used versus when we were out during the day.

some guessculations. Let's say the DC-AC converter in the car requires 440 Volts DC input.
Each 3100mAh@3.7 Volts = 11.45Wh per li-ion cell. To achieve 440VDC requires 119 cells connected in series. The Watts(power storage) from such a series connected pack = V*I or 440.3*3.1 = 1365Wh. To make an approximately 85KWh pack requires 62 of the series pack connected in parallel. 62*1365=84.6KWh (7378 cells). so when the first cell fails in the car, you will loose 1365Wh of storage because you will loose the other 118 cells in the series chain. The car will function normal with the loss of range. The good news is once you replace the offensive cell, you'll have your full range restored. To create lower Watt-hour rated packs, Tesla has two options, use fewer packs in parallel or use a much cheaper cell like the 2250mAh cell. These cells are the same physical dimensions as the 3100mAh cells. So my guess is Tesla is going to use the lower rated cells to produce the lower rated battery packs. The main reasons are ease of manufacturing and predictable crash test results. As in the past, future cells will have the same form factor with higher capacities. Panasonic is already making these cells with 5000mAh capacity or more.

Speaking of replacing, suppose a 40 or 60kWh owner prepays the 85kWh battery under the new plan? I don't see any restriction to replacing only the same size you've got.

Supercharger is the only complicating factor

Is it seriously a pre-payment for the battery 8 years down the road? Or did they just announce what it will cost at that point? You don't have to put that money down now do you?

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