You CAN tow with a Prius

"Not sure what you found alarming."

The precipitous drop from 7 to 2 bars in 16 miles was alarming to me. Never saw that before (never towed before).

If I continued on 16 more miles on an expressway (I came home on I-95 with AC on), would my big battery be DOA?

I was going to test my set up with a trip across Florida to visit my sister, 3 hours and 150 miles, before tackling Florida to New York. Now I'm not sure if I should even try that.

Any problem indicators I should look for? Drive the car without the trailer and see how fast the battery reading climbs back up?

Not sure if this is helpful to your engineering mind (which I appreciate), I did a Dr. Prius analysis of the traction battery several months ago and it showed 50% life left.

The drop in mileage I can live for the trip. I just don't want to kill my Prius (although part of the plan I liked was having two good vehicles in case one breaks down).

P.S. what is S4 mode?

 

Yes you'll be fine. It is normal. Obviously drive around town with any new vehicle modification before heading a thousand miles away!

S4 is fancy speak for when the engine has warned up and shuts off for itself at a stop.

 

I always "S4" my car before I drive off. Long-standing habit, it just always felt right.

I'll give towing another shot with your encouragement -- thank you for that. I had already taken beauty shots of the trailer and written an ad to post tonight. Not terribly difficult as I "engineer" advertising as my profession.

 

You mean you speak Chinese and spent near 8 years developing your design with the lead engineer of a major battery manufacture to not just produce but thoroughly torture test the product and post all those tests as video on Youtube?

I don't think so... Not once in all the years you've been posting have you mention or link to failure testing of your cylinders, which is actually very irresponsible considering that Bumble Bee designed the same modules as you and they've exploded at the welds between cells during high temp discharge and recharge. And again the only evidence of these lithium packs being a fire hazard is from you and you have no data to back it up. Even the science of this type of lithium chemistry makes it clear that this is the least flammable of all the lithium types. But go ahead, keeping spewing your nonsense.

 

And blocked...

 

Drove around the block twice, maybe a mile, at 30 mph and battery level jumped from two bars to six bars in five minutes. Perhaps there is hope for towing yet.

Did a Dr. Prius/OBDLink life expectancy test for the big battery and got 48.68% capacity. Exactly eleven months ago it was 50.85%.

Did the full battery test and no error codes showed. Battery monitor results shown in photo -- Greek to me, but if there's anything I should know or keep an eye on if I'm towing, please advise (and thanks in advance).

 

This is partly mental, and party real. Your car has probably been doing this for ages you just don't watch the screen like a hawk. Most people don't! The battery level in the car is perfectly happy at 2 bars indefinitely. It is also perfectly happen at 7 bars indefinitely. If the bars get to 1, the engine will kick on and charge up to usually 3-bar or 2-bar. If the battery gets up to 8-bar, the engine will also kick in except as an air pump to lose energy.

The Prius learns and tries to keep you in the blue. The 3-bar to 6-bar range. This is not the only normal healthy range. It is just what the car prefers because it gives you enough uptop for regen and also enough below to be able to draw out the power the Prius needs for getup and go.

The only time the bars won't charge up, is if you're pulling out more power than the engine can provide by regeneration for extended periods. This is usually only extended accelerations. Just search the forums for a Prius driving up I-70 through Colorado especially the high grades between Denver and the Eisenhower Tunnel. No Prius will get to the top without fully discharging its pack. And once that happens you only get the output power of a 1960s' VW beetle trying to pull a 2000's SUV worth of vehicle. You may run into this because you are going to use a lot of acceleration. It is a different skill to drive a Prius with a discharged pack. And no that's not dangerous or bad, it is just different. And for some that live in the hills, normal daily. Once you hit that discharge, you keep your foot steady. The second you lift off the go pedal, you will lose that acceleration and you aren't getting it back. For you this will be towing a trailer and merging onto an interstate with traffic flowing at 85mph. You are going to want to punch it and get up to the max towing speed ASAP. Light foot driving doesn't work.

As with any towing monitor the temperatures. Be careful with your brakes and keep your distance. You have regen and friction so it's better than most vehicles. But pads in the Prius can and will overheat. If you are in stop and go where you're using the friction brakes and lots of heavy acceleration (stop to a few mph and down again) this could overheat things so check it out from time to time.

 

2K1 ... you're generous with your time and expertise, man. Thank you. I am happy to do the same on the BMW maxi-scooter forum (and still find it a hoot that my 3,048 lb. Prius gets better mpg's than my 545 lb. two wheeler, 52 to 48).

I have figured out basic maintenace on the Prius, from oil and ATF to plugs and pads, even throttle bodies and MAFS, but electrical stuff is beyond my ken. Knowing "the car is perfectly happy at 2 bars" is fantastic! I will drive the trailer around for a day or three, then load the bike on and try that for a few days. If all goes well, I will visit my sister on the left coast of Florida.

 

Ah, you come from owning ze German vehicles.

The long standing cliched anecdotes about German vs Japanese design definitely hold true on the Gen2 Prius. Remember they over engineered the crap out of it because 2004 was still hybrids were scary. The spaceship was one of the first out there.

Pretty much anything in the Prius that doesn't display a warning light, is fine. It is designed with abuse and neglect in mind and the engineers hide what's actually happening. For example the Prius when it shows 1 bar is 40%. You can put it into out of gas mode and drive it down to 10% battery and it will still start right back up and work with no damage. But it won't let you, and it won't tell you. 1 bar = low is all the info you get. Compare that to my German 350e which shows you the actual percentage of the battery. It will with some pedal modulation get down to 6% or so state of charge which really means 6%. You can never get lower in normal times. If it does go lower, it shows you. If you charge it all the way up to 100%, it is 100% and you can damage it long term. The Germans give you all the information, remove the kid gloves, and say do whatever you want. All the tradeoffs are in the 1000page manual you have memorized cover to cover right?... Right? In the Benz if a light comes on, something has died. No lights but proper information could be damaging. Lights are damaged. Toyota is lights on could be damaging (inverter overheat) but then could go away once it's gone. And no lights no damage. Very different.

Enjoy the towing! I don't know if the pics are still up but the ones of Bob's plane is pretty cool.

 

#1 son gave me an ancestry.com membership and I discovered my mom and dad's ancestral towns are < 50 km apart in southern Germany. That's my trip for summer 2023.

I'm on my 4th BMW mega-scooter. Favorite feature is information-related: live tire pressure. Reifendruckcontrolle! (for true authenticity, cough up half a lung as you pronounce it). BMW is also getting the hang of the electric motorcycle with the new CE04. I will own one of those someday.

This is what I'm towing.

 

Hope he feels better now that he can't see my comments... Seriously folks, if you have a start up hybrid battery replacement business and a competitor comes along with a seriously impressive alternative, it's not in your best interest to make wild and entirely unsubstantiated accusations about safety when your competitor is doing impressive and entirely safe design work.

That's such an amazing motorcycle I almost thought you were going to show us what it was towing, not that it was what you were towing...

 

If by this you mean the shutdown in the first 70 seconds of starting up, that is passing from stage 1 (S1) to stage 2 (S2). Stage 4 (S4) happens much later—some 17-25 minutes of driving.

You can learn more about the Prius' stages of warm-up by clicking on the link (5 modes of Prius Operation.) in my signature below.

 

If stage 2 is the point where the gas engine shuts off after 70 seconds, that's what I do before driving, at least when the engine is completely cold.

Another habitual thing I do, because I drive my Prius so rarely (fewer than 2,000 miles a year because I prefer the bike except in rain), is turn the car on daily to let it reach stage 2, then shut it off. I have no science for this. It simply feels like it's good for the vehicle. Machines like to be run rather than sitting for days at a time, right?

Good thing to do or needless?

 

I towed a 2200lb U-Haul trailer with my Prius about 1100 miles after finishing military flight training. Not doing that again because it's sketchy, but some of you PriusChat people are absolute risk-adverse nerds.

 

Aversion to risking my own safety makes me a nerd.

Aversion to risking other people's safety makes me decent.

 

Yeah, that's almost as much weight as an unloaded Prius... The laws of physics don't play nice with a rig & trailer balance like that. Heck, even towing half that total of 1100 is up near the limit of my comfort levels and if I'm hitched up I don't do the freeway, just around town at 40mph or less.

 

Well that is 227kg over the safe limit. No wonder it felt sketchy. Good luck in your next life.

 

Let's see, 2200 lb is about 998 kg, 998 minus 227 is 771 ... SRQ's profile says a 2008 (Gen 2) Prius ...

do you have some information that gave 771 kg as a safe towing limit for a Gen 2 Prius?

 

750kg

 

User experience is what we got to go on because Toyota's lawyers prefer the vehicle is not used for towing so they'll always say they didn't study it.