underbody protection

I was wondering does an i3 bottom out easily, as part of my normal use I visit a forest which has a poor road. I am concerned that an i3 would bottom out easily and is there much I could do to protect against this happening such as fitting a protector?I suppose I could leave the car at the forest entrance and hike the 1.5 km .
I will purchase a new or 2nd hand i3 within the next year, I love this forum
Thanks in advance for all replies.

Fore a road car I3 is actually quite good for ground clearance, my concern would be more that you have only a can of Tyre sealant as a back up in case a rock or tree branch damages a Tyre beyond what the sealant can cope with, Then you have no jack either so you will be stuck. plus 1.5 Km is not really a hike

It is my understanding there is a thick steel plate on the bottom of the car to protect the battery pack. I'm not sure what else you would want to protect. Its not made for off-road.

I'd be surprised if the bottom of the battery box is steel.

jadnashuanh said:

I'd be surprised if the bottom of the battery box is steel.

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Not the bottom of the battery box, I'm sure it's aluminum. But exterior to that a steel plate, it's been discussed before and comes up every time someone freaks out about the few Tesla's that caught on fire I in their early days which prompted them to add a titanium plate on the under-side of the car to protect their pack. BMW went with steel as it's cheaper, but seems to be effective as we haven't seen any i3's burn from debris penetrating the pack.

There is a steel cross plate, but it is above the HV battery, according to a BMW technical training doc.

I can't find the source, but it was a good source.

I'd be curious to see your source if you ever find it.

Here's an automotive tech giving an overview of how he removed ("like, so many bolts") the i3's high-voltage battery. You can see there's nothing between the HV battery housing and the road:

https://www.youtube.com/watch?v=L6DVQnHQHPM

Your video doesn't show the bottom of the pack.

Sure thing. Here's a better view. Looks like aluminum to me:

Correct, aluminum does not corrode, steel has as tenancy to rust. Supposedly the steel is between two layers of aluminum. If the car only has soft aluminum between it and the battery pack then we would probably have seen some i3 fires by now. You see the stamped lines in the aluminum? Most likely the location of the steel plates.

Depending on the alloy and thickness of aluminum utilized, it can be as strong or stronger than steel.

jadnashuanh said:

Depending on the alloy and thickness of aluminum utilized, it can be as strong or stronger than steel.

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Exactly! Our all-aluminum Honda Insight has fewer door dings than our previous steel-bodied cars because its aluminum alloy is not particularly soft. Also, if steel is sandwiched between aluminum layers, the layers had better be totally sealed to prevent moisture from causing rapid electrolytic corrosion of the aluminum that's in contact with steel. Any damage done to the bottom aluminum layer could lead to significant corrosion. Doesn't sound like a great solution.

I would think that an aluminum plate would be sufficient, but maybe BMW didn't agree and there's steel there. Anyone try sticking a magnet to the bottom of the battery box?

alohart said:

… Anyone try sticking a magnet to the bottom of the battery box?

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I was too to report this yesterday, but after my shift, I grabbed a Harbor Freight LED (with a magnet) from the garage workbench and tried it out in various spots on the HV battery housing. It did not stick anywhere.

As I mentioned, imolazhp, if you happen to find that source, I'd be curious to read it. Thanks.