Written by Heather Watson

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12 Comments

  1. Lori Jacobs

    Can I just say, as someone who was a tech for about 15 years and since then has run a daycare and transported many of the kid, that we need a safe product for this problem? Im thinking something universal by IMMI that mfrs could test with their products, not an Amazon product. Then perhaps parents who need it could order it from the car seat mfr?

    I know the testing is complex and they have to get the nod from the vehicle mfr as well. But if IMMI is doing it, theyve already got ins there because they make so many parts for both vehicle belts and car seat buckles.

    Reply
    • Heather

      I agree. I have a heck of a time buckling in to the buckle in my husband’s back seat and I’m fairly narrow. There has to be a better solution. Part of the problem is that IMMI doesn’t make all of the vehicle belts and there’s no universal buckle design. If there were, it’d be so easy because a buckle extender could be manufactured to plug in and actually stay buckled. Alas.

      Reply
  2. Mike

    Its not very realistic to buy your car based on how car seats will fit. Its also impossible to anticipate that it wont work in the future. For example, I bought my car 2 years ago and car seats fit just fine. Now that Im hooking up a booster for the first time, I find that its impossible to click the seatbelt with the booster in place.

    Im not sure I see an alternative to an extender. Wont a sturdy extender only make my cars buckle reach like it would in another vehicle?

    Reply
    • Heather

      If it’s down to a choice between 2 vehicles, having the knowledge about the difficulty of buckling boosters into buckles that are flush with vehicle seats is realistic. You need your vehicle to fit you and your family. Some cars don’t fit small women well; why should a small woman buy a car where she must move her seat all the way forward so that the steering wheel is on top of her chest? I’ve seen it. But there are others where pedals can be adjusted for a safer fit.

      I’ve explained the dangers of extenders above as they change the placement of the buckle on the child. There aren’t sturdy extenders. Crash forces are extreme and as consumers, we don’t know of what types of metals companies are making them. Those that are made by vehicle manufacturers say not to use with child seats and child seat manufacturers say not to use extenders. I think the easiest thing to do is to find a narrower booster. It sucks to have to buy new seats when you think you don’t.

      Reply
  3. Linda

    What high back booster can we use with Tesla Model 3 that works with headrest and not covering the buckle? Britax, Chicco, Maxi Cosi are out.

    Reply
    • Heather

      Hi Linda. I’ve gotten approval for the Nuna AACE, the UPPAbaby ALTA, the Peg Perego Flex 120.

      Reply
    • Tess

      What age and size of the child? Up to 25 kg you can buy a car seat that you fix to the car by the seat belt and/or isofix and/or top tether. And the child is buckled by the 5point harness of the children car seat. Britax Multi-Tech and Max Way, Joie Bold and some others. And the children should remain at least until 4 years and 18 kg rear-facing, that covers the first two seats mentioned (they are both ways). I have Klippan Century, rear-facing up to 25 kg, safest option if not counting Klippan Opti126

      Reply
      • Heather

        Thanks, Tess. The Tesla Model 3 has a difficult buckling situation and she was looking for a booster for her child.

        Reply
  4. Victor

    FYI: speed x weight is not a force.

    150 lbs x 30 mph = 4,500 lbs * mph.
    Not 4500 lbs.

    When in cruise control at 60 mph vs 20 mph on flat ground going straight, the amount of force on the seat belt is equal since there is no acceleration.

    Newtons 2nd law is Force = mass * acceleration
    F = ma

    When you are in an accident and go from 30 mph to 0 mph in a fraction of a second, you are generating a (negative) acceleration value. It is that acceleration that is applying force (F) to the seatbelt, which is the same force the seatbelt is applying to the child.

    In practice, for vehicles, we define the acceleration amount as a multiple of g, which is the acceleration of an object in free fall due to gravity, where g = 9.8 meters/second^2

    In crash testing, dummy models can have up to 60 gs of force. Ideally it would be much lower (eg 30).

    But that force being applied to the seatbelt is effectively the weight of the person multiplied by the # of gs.

    So a 150 lb person at 30 g during a crash would generate 4500 lbs.

    *of note, the term lbs is a force that already incorporates mass * meters/second^2 and multiplying by the constant g does not require multiplying again by meters/seconds squared, so the final units of force is still lbs.

    Reply
    • Heather

      Yes, thank you. The problem is that if we try to explain this to parents who dont have a physics background, or even a science background, their eyes glaze over, lol. We have, at most, 30 seconds, to spit out an explanation to convince them to keep their kids snugly harnessed or belted. So, this speed x weight = force equation was used instead. Its basic and gets the point across, and I will edit the article to show that.

      Reply
  5. Patrick

    I completely agree with Victor “speed x weight is not a force.” F=ma, not F=mv!
    When reading this page and seeing your diagram it immediately made me question the quality of the content of this entire page!
    If you are going to simplify for the readers without a science background you should start by stating that you are making an simplification to get your point across. Otherwise as a reader, I am left to wonder. If this author doesn’t understand basic high school science what else do they not understand. Perhaps they are not a credible source and I should look for information elsewhere.

    Reply
    • Heather

      OK, fair point. The edit I made didn’t get the point across so I’ll try again =.

      Reply

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