What happens if the Model S bottoms out, say on a steep driveway or grade break? What happens if you hit a large object or debris that may be lying in the road? Will this damage the battery pack?
nothing... it will be designed to cope much like a fuel tank at the bottom of a gas car...
Actually, less is likely to happen. Remember that a gas tank holds liquid, so a puncture in that causes a flamable fuel leak. If you manage to puncture the battery pack, the worst you could do is sever the coolant line and make take out a few cells.
Taking out a couple of cells would be nothing, Tesla's Roadster design lets them isolate a cell if it becomes damaged by any means without concern to the other cells around it.
The coolant leak is a little more of an issue, since it means the car's charge/discarge cycle won't be regulated as closely, meaning it may take a little longer to charge, and you might get a limit placed on high end acceleration.
Take your pick of which you'd rather, I already KNOW which scenario I'd prefer.
Some interesting interview info:
The car will be offered in three ranges, with battery packs offering 160, 230, or 300 miles worth of juice. Each pack will be the same physical size and each can be removed in under a minute -- assuming you have your sockets handy. About 30 bolts are entailed and, while we still don't have hot-swappable battery stations available anywhere, Peter indicates that's absolutely still a goal for the Model S. That said, 480 volt charging will be supported by the car, which in other EVs provides an 80 percent charge in about a half-hour.
If "taking out a few cells" requires replacing the pack, I would like to know what kind of warranty there is for the pack. Bottom touches with six inch ground clearance with long wheel base pretty much can't be avoided in some places. I rather get a leak in gas tank (which is very unlikely to happen, because there is a lot more in a way than there is with Model S battery pack) than need to replace entire battery pack.
I imagine your insurance would have to cover that, not Tesla.
Where does it say you need to replace a pack if a few cells are bad?
I don't know what the cutoff is, but I'd bet you need to loose about a third of the cells in the pack before you'd need to get a new one.
Ugh, we've been over this before in another thread.
This particular issue has not been discussed. What happens if you do that bottom hit, not do you do that bottom hit. This is "what if" not "does it happen".
I don't know if I need to change entire pack, that's the question. Can you fix it without? With already limited range loosing even one fifth would be a lot, you'd need to fix that. Battery is the single most expensive part of the car, it needs to be protected, so bottom armor needs to be tough.
No matter what everyone says placing it in the bottom middle of the car puts it into vulnerable position. That position needs to be protected, and "what if" needs to be addressed somehow. Either making that protection good enough that you don't need to fix the battery even with 60mph bottom touch situation or you need to be able to fix the battery without replacing it.
It's vastly overblown concern. Tesla has stated the battery is designed to be part of the structural integrity and they're aiming for a 5-star crash rating. And you're paranoid scraping over a speed bump is going to damage it or a rock hitting the undercarriage on the freeway?
A 60 mph bottom touch? Seriously? Has that ever happened to anyone you've ever heard of in your entire life? What are you doing with your cars, off road rally racing?
I get you're concerned, you've stated this concern multiple times and justifying it by inventing absolute disaster scenarios that aren't even remotely reasonable to consider.
Tesla will have designed the battery to cope, not least because it's in their interests to have a robust and reliable product.
If this is a serious issue for you then can I suggest you don't purchase a Model S? You will find cars with batteries in many different locations, I'm sure one will meet your needs.
60mph was a mistake, I was thinking km/h. 60km/h bottom hits do happen sometimes, 60mph I don't recall happened to me ever (unless you count ice as bottom touch).
That's not the real concern though, much worse is bad road, slow speed where there is some big rock hidden in middle of the road that your car hits the bottom. Entire car mass hit in relatively small area makes quite a big force.
5 star crash safety says nothing about battery durability. Neither does being structural part of the car. I'm fine if someone tells me that this is addressed somehow, but this far nobody has. All I see is people trying to sweep the issue aside like if it doesn't exist.
Note that I do believe protecting it can be done. I'm just not convinced that it has been done.
I'm not sure why something big in the road is a concern. I mean, beyond it'll crunch you in general. It'll fail to clear the fascia first. Then it'll fail to clear the front axle. Then finally it'll go to the undercarriage where the battery is. If what you hit is going to plow through your axle still in one chunk, then yea, your battery is probably toast. Probably your axle too. And probably the fascia.
I certainly understand resisting rocks kicked up by the tires, but I'm not quite visualizing how a really big rock (taller than 6" I guess since that's the Model S clearance) isn't already going to mangle your car pretty seriously anyway.
Oh, as for "sweeping it aside", it just seems like a bizarre fixation to have. It feels akin to me asking "Have Tesla insured the car can take lightning strikes? It's an electric car, that could be extra bad. I don't want anyone sweeping this concern aside as if the issue doesn't exist."
First, I have yet to see a roadster owner report a problem hurting a car due to clearance. Many other cars have lower clearances. Although only true for fascia, my brother's new CTS ranges from 4 to 5 1/2 inches.
Second, Tesla has designed the battery packs for redundancy. If individual cells stop working the rest continue working. I have not seen a technical explanation of how many can die before affecting performance or worse yet no longer working.
Third, the pack is very stiff. I believe it is aluminum. It has dimples for added rigidity. It holds ethylene glycol (antifreeze) and nonvolatile batteries. The batteries get warm but don't tend to explode or burn. The pictures make the shell look very thick.
Ever hit a pothole? Then imagine a lot worse case in some semi-wild dirt road after winter (maybe you just don't know what bad case of ground frost can do to a road?). Rock doesn't need to be big, it doesn't even need to be very visible, you just hit bottom because your front tires go thru a dimple into road. Or side of the road collapses a bit after you have already cleared the front of the car over the rock. Those things happen. Not often but they do.
Short wheelbase helps. Having decent ground clearance helps. Having decent bottom armor helps. Does Model S have any of those?
I don't know where you plan on taking your car, but it sounds like you need a military vehicle.
Common sense tells you that if you hit something hard enough it will break. The Model s will be no different.
Spoke with a sales rep. Said that this issue has been brought to their concern and that they have already thought of it and it will be a priority.
It only makes sense, batter powers car and is at an exposed position, so they must protect it. I figure there will be an aluminum plate across the bottom or the batter just lifted an inch or so above the very bottom of the frame. who knows what they have but i am sure they will think of something
Thank you msiano17. You are first to say something concrete about this. It is good to know that Tesla has realized the potential issue there is, and based on their very good record on solving such problems I can be sure that something will be done to protect the battery.
QWK:You don't need to do military dirt roads just normal city traffic. I live about half a mile from I think the 4th or 5th busiest intersection in Oslo. It has about 6 different tram routes, a subway, a major highway and like 8 bus routes all through the same intersection. That intersection now in the early spring also has a pothole which I'm pretty sure I can get my front wheel into. That's a busy intersection, now imagine how the smaller streets looks. Especially those where our 80 metric ton trams pass every 10 minutes. Combine that with Oslo's winters and you get why we sell so many crossovers or cars with slightly higher clearances.
It seems though that Tesla is on top of this, they obviously see the problem with dented batteries as well.
To contribute to the discussion regarding the hit,I read in a newspapers that Hyundai will use a new kind of lithium ion battery designed by LG CHEM for a new hybrid car. They have increased the efficiency of the battery by saving 44 % of the volume and 25 % of the weight (for a given energy). In addition this new battery does not contain liquid but a polymeric substance. Seems promising !
About the Model S, it could be useful to have the possibilty to buy a model S with the small batteries pack for a daily use (short distances for going to the office or to go shopping) and rent a big pack for a short period (holidays if a long range is required). May be is it foressen by Tesla ?