Can I tow a small trailer?

[adric22]

I've been searching through the forums and I've seen several of you have installed a hitch on the back for bike racks or wheelchair use. We're thinking about getting an i3 Rex and we were curious if there would be any problem towing a small trailer. This wouldn't be a common activity, maybe 3 or 4 times per year for 20 miles or so. The trailer would be probably no more than 300 pounds, with no passengers in the car. I know BMW wouldn't condone it.. but It seems like it would be fine. I just wanted to see if anyone else has tried it, since my wife will not go for the i3 unless we know this can be done. it's sort of a deal-breaker for her.

 

[Tooks]

It can be done, of course, as others have already done so.

The problem is one of liability and litigation should anything go wrong when you're towing a trailer with a car that is not type approved to do so.

I'm not sure where you are, but in the UK, there would be car insurance issues if anything were to happen whilst towing in a vehicle not approved for it.

 

[Gif]

Go on, I'll ask the obvious question!

If it's only 300lbs and you've got no passengers, why don't you just put whatever it is in the back with the seats down?

 

[alohart]

If it's only 300lbs and you've got no passengers, why don't you just put whatever it is in the back with the seats down?

Maybe that pile of manure for fertilizing the garden wouldn't smell so good inside the car

 

[bwilson4web]

There are oversized loads like sheets of plywood that are best transported on a light trailer. The mechanical, receiver is not the problem.

In the USA, we need to have lights, especially stop, turn, and running lights. These need to tap into the rear light circuit and at least our local BMW tech does not think this is easy to do. I also contacted the seller of our hitch and they don't know of any wiring kits.

Bob Wilson

 

[jadnashuanh]

The i3, like probably all BMW's and many other cars these days, rely in the serial CANBUS to tell things to turn on and off. FOr example, on my ICE, the rear light assembly has: brake, running, turn, fog lights and only 3-wires going to it. Now, you cannot individually control four things with only three wires without some 'magic' going on. If you've ever looked at some of the switches in a BMW, you'd find that they are usually microswitches, and definitely aren't designed to support actually switching power to things...they send a signal to the computer, and it then talks to a driver closer to the device. On my ICE, when a trailer is attached, it does numerous things: turns off the US sensors in the rear, changes the rear camera view to make it easier to line up with the trailer, modifies the stability control logic to account for the trailer being there, and last, but not least, controls the trailer lights, and if it needs to, its brakes. I doubt the i3 has the corporate logic to accept a trailer logic module, and that means, if you were to do one with lights, you'd need a passive CANBUS system to listen and then drive the trailer's lights as required. To ensure that at least the brakes and emergency flashers work, in addition to connecting to the CANBUS, the device I have for my ICE, also connects to the center brake light and the right-hand turn signal...when the car is off, it sees the center brake light, and will activate the brakes on the trailer. Same thing, it sees that the car is off, and the right-hand blinker is on, then turns on the flashers. When the car is on, and the CANBUS is properly functioning, it ignores that emergency logic. If you just try to tap into the lights to power the trailer, you'll probably cause the car to at the minimum, issue warnings about the lights, and at the worst, fry something.

 

[bwilson4web]

. . . For example, on my ICE, the rear light assembly has: brake, running, turn, fog lights and only 3-wires going to it. . . .

Sorry, what is "ICE"?

In the Prius forums it means Internal Combustion Engine (ICE).

I did find the BMW towing kit site: https://www.getbmwparts.com/partlocator/index.cfm?action=AccessoryCatalog&siteid=214672&catalogid=4462&categoryID=184334

Bob Wilson

 

[engineear]

ICE= Internal Combustion Engine

 

[jadnashuanh]

I have two cars, an ICE and the BEV (as others have said, internal combustion engine). The ICE, at least in other parts of the world, that I have, is available with a factory towing option, so the embedded logic is there, if you add the right hardware. I seriously doubt it is there for the i3. While the single-speed transmission on the i3 works fine for moving itself, I'm not sure it would be the best for towing a trailer, either. Then, since it wasn't engineered to tow a trailer, I'm not sure (and I wouldn't want to be the test vehicle for it) that the structure would work long-term if you did on the i3. It could be fine, but you certainly wouldn't get any warranty claim if something in the drivetrain or chassis failed if you had a hitch installed since it was never designed for it. It's one thing to add one to a car that was designed for it, it's another entirely, to add one to a car that wasn't.

 

[bwilson4web]

This is good advice for non-technical folks:

. . . It could be fine, but you certainly wouldn't get any warranty claim if something in the drivetrain or chassis failed if you had a hitch installed since it was never designed for it. It's one thing to add one to a car that was designed for it, it's another entirely, to add one to a car that wasn't.

In my case, I'm pretty comfortable with my experiments and since it is not 'leased', I'm having a ball. FYI, here is another tow experiment:

Bob Wilson

 

[jadnashuanh]

The question I have to ask is, is that vehicle, in any market (maybe not the USA) designed to use a trailer hitch? I didn't have a problem with my GT. While BMW chose not to offer the towing package on it in the USA, it is available most anywhere else in the world with one...the frame and attachment points are identical. BMW does not offer a trailer hitch anywhere in the world for an i3 that I've seen. You're into uncharted territory. Throw in the CFRP frame, and any mods you might make have NO history, unlike the millions of steel bodied ones out there and many decades of experience. Good luck getting a lighting package to work, too. A small trailer probably would not have brakes, so that's a little easier.

 

[bwilson4web]

. . . BMW does not offer a trailer hitch anywhere in the world for an i3 that I've seen. You're into uncharted territory.

Agreed.

. . . Throw in the CFRP frame, and any mods you might make have NO history, unlike the millions of steel bodied ones out there and many decades of experience. Good luck getting a lighting package to work, too. A small trailer probably would not have brakes, so that's a little easier.

The rear-drive, 168 hp means the mechanical stress from the tow receiver is coupled via the motor frame, not through the CF body and body frame.

The combined wheel chair and carrier run about 100 lbs and there was no evidence of suspension problems or raised, head lights. Not a full test but encouraging. I may wind up using some spring, stiffener inserts when towing a large load.

The trailer lights are something else but I do not have to tap the vehicle electrical system. Photo detectors outside the existing lights feeding amplifiers and a trailer power supply would work perfectly fine. But I might tap the 12V supply to simplify the power supply.

Bob Wilson

 

[imkazaam]

Bob,
Have you tried anything bigger since?

 

[kakaronaldo]

that is a nice post....and I agree with the third comment about that...