Ran out of juice, 12V and main pack drained, need info.

[dsm363]

Ran out of juice, 12v dead, main pack dead, need info.

I think the big lesson here is never count on a single mile past zero. Treat zero as zero and everything else is bonus. Also, you are better pulling off the highway at close to zero and calling the tow truck then especially if in the cold and in the middle of nowhere. That way you have enough juice to keep car warm and put into tow mode. If there is a gas station or restaurant then pull over and see if they'll let you plug into a 110V outlet to trickle charge until tow truck comes or you figure out you have enough charge to make it home or a level II charger. Also, if possible, try and leave your last charger with a decent buffer for unexpected storms, cold...etc. Not always possible though as can't predict everything of course.
Check out thread from ChadS about planning road trips too.

 

[dave]

The other lesson is buy an 85 if you can afford it at all and have any plans to drive outside your normal commute!

 

[andrewket]

I'm glad to hear you're back up and running. Thanks for your tips/lessons learned. Personally, I liked it better when Tesla did not "hide" range below zero. I understand why they made the change. Tesla is trying to make EVs easy to use for everyone. And right or wrong, most of the world assumes that they can drive a few more miles after the "gas" gauge starts flashing E. Having said that, I'd like a setup option to disable this behavior, and for rated mileage to show actual capacity. Zero means zero. The default can be the current behavior of hiding some capacity.

If Island had this, he would have known he wasn't going to make it and pulled over much earlier. The situation would have been bad for sure, but no where as bad as it was. Right now we're left guessing. A driver shouldn't have to run a linear regression to try to figure out how much capacity is left in the battery.

My $.02

 

[dsm363]

Ran out of juice, 12v dead, main pack dead, need info.

Zero means zero also means pack can't be left at that level for any significant time without chance of ruining the pack and needing a new one I think. Tesla had decided it is better to leave a buffer to protect the pack and not anger owners if they drive to zero, can't get it charged for a few days then are angry then need to spend $ to buy a new pack (or Tesla spends that money under warranty). Also, I'd imagine people what to know down to the tenth of a mile how far they car drive and Tesla can't accurately predict that (weather, elevation..etc). Having a zero with 'charge now' means Tesla can no longer safely predict how far you can go so you should do what it is telling you. A true zero also wouldn't allow you to put car in tow mode I think and could drain 12V quickly.

 

[Caloncho]

wow Islandbayy... I am sad I am not near your dead MS to help you start it, rope tow it (or at least go put plastic on your rolled down windows, or rescue your valuables). Good vibrations going your way. Hang on.

 

[andrewket]

I just sent this to ownership@

[FONT=arial, helvetica, sans-serif]Ownership team - if you would pass this feedback along to product/engineering I'd appreciate it.[/FONT][FONT=arial, helvetica, sans-serif]
[/FONT]
[FONT=arial, helvetica, sans-serif]Feature request[/FONT]
[FONT=arial, helvetica, sans-serif]
[/FONT]
[FONT=arial, helvetica, sans-serif]At some point, I think it may have been firmware 4.5, Tesla changed how rated range was calculated and displayed. Specifically, prior to this version the rated range displayed to the driver was the full capacity of the battery, minus a reserve that is not accessible to the driver to keep the battery from bricking. After this version, Tesla reserved additional capacity that is accessible to the driver but is not included in the rated range display. In other words, after this change it is possible to drive below 0 rated miles.[/FONT]
[FONT=arial, helvetica, sans-serif]
[/FONT]
[FONT=arial, helvetica, sans-serif]I understand the business reasons for this change. Tesla is trying to make EVs easy to use for the masses, and emulating the behavior of an ICE car that has some gas left after the fuel gauge starts flashing E likely meets customer expectations. Unfortunately, this has a negative affect in that the driver doesn't know how much energy or range they have left after hitting zero. As a driver, you're left making estimations. On the forums, some have even described performing linear regressions to estimate how much capacity is left after hitting 0. In an ideal world, drivers would pull over immediately after hitting zero. But that's not what they do. They push it, because there is this unknown "reserve" and without data, they decide to risk it.[/FONT]
[FONT=arial, helvetica, sans-serif]
[/FONT]
[FONT=arial, helvetica, sans-serif]I would like an option accessible via the configuration screen to toggle how the rated range is calculated. Option 1 is the default, and is the current behavior, with some amount of capacity in reserve. Option 2 displays the rated range with 100% of the capacity is that is available to the driver. If you hit zero, you're done, the car shuts down.[/FONT]
[FONT=arial, helvetica, sans-serif]
[/FONT]
[FONT=arial, helvetica, sans-serif]I think this would meet Tesla's goals of making EVs as easy to use as possible, while simultaneously giving drivers the option to understand the actual state of the battery.[/FONT]


[FONT=arial, helvetica, sans-serif]Thanks for your time and consideration,
<name, VIN removed>

[/FONT]

 

[FlasherZ]

I've always wondered how many amps are necessary at the 12v posts to power up the car if the 12v battery was dead or near dead. Assuming the main pack has juice (and not islandbayy's scenario where both the 12v and the main pack are dead), anyone hazard a guess how much power is necessary to go through the steps to throw the relay on the traction pack?

No idea.

Using the old vampire load data you can probably make an educated WAG. I guessed at 30A (360W) myself, but that could be way, way off.

 

[dsm363]

Ran out of juice, 12v dead, main pack dead, need info.

There is a big difference between a fuel gauge with a thick needle on a line that says Empty and a number that says 3 miles left. You have no idea really how far you can go with the ICE but if the EV says three miles then many expect to go three miles even in a snow storm driving up a mountain. Tesla had to account for that so leaving a small buffer is a good idea. You know when you hit zero it could be one mile or ten but you know it is time to pull over and come up with a different plan other than trying to make your destination if it is cold and dark outside.

 

[FlasherZ]

If Island had this, he would have known he wasn't going to make it and pulled over much earlier. The situation would have been bad for sure, but no where as bad as it was. Right now we're left guessing. A driver shouldn't have to run a linear regression to try to figure out how much capacity is left in the battery.

I think many people know that beyond "E" on a fuel tank on those antiquated ICE's, there's a "reserve" (2 gallons or so). I know people who religiously count upon that reserve as their indicator to go get fuel, and I know people who don't let the gauge go below 1/4 tank because they've been burned before. I can tell you my '64 1/2 Mustang goes completely empty at 1/8 tank and runs out, so I never let it get below 1/4 tank.

Bottom line, Tesla won't be able to adjust to everyone's preference for managing where '0' lies. I don't do any analysis, I figure '0' is '0' and would only go beyond zero to pull off and find a plug. I wouldn't try to stretch to 5 or more.

 

[omarsultan]

Your experiences explain this dialog that popped up for me the other day. It confused me a bit, but I can see now hoe the battery heater kicking in could quickly kill the expected range.

O

 

[Cottonwood]

After reading all of this, the option that I would like to have is the ability, when stationary, to have the motor inverters produce enough electrical output to drive a 14-50 outlet (equivalent outlet in other parts of the world) in the car. As more Tesla's are on the road, it would allow one Tesla to provide power for an emergency charge to another Tesla, plus allow a great source of backup power during power outages. 50A contactors only cost 10's of dollars to make this intermittent connection when needed.

This is the electrical equivalent of siphoning gas from one ICE car to put in another. I've done this several times in cars, trucks, and snowmobiles to help others. Luckily, I have never had to ask for such help...

I understand the reluctance of Tesla to do utility load balancing on a daily basis; that is a huge cycle load on the battery. However, those big inverters are already there to power the drive motor; why not give the option to tap some of that power to help other Teslas and provide emergency power when needed.

Imagine Tesla central being able to send out text messages to Tesla owners within possible range to help. To keep this from being abused, Tesla could charge the equivalent of a tow charge for the matchmaking/dispatch service and offer the donor car that dollar amount (or more!) as a Good Samaritan credit towards future service and accessories. This would make a pretty awesome self-supporting system of EV's.

 

[NigelM]

Discussion about what reserve you have below zero is misleading at best and potentially dangerous. The reason that reserve is there is to account for different weather and road conditions; this thread alone proves that the reserve shouldn't be counted on to get you to your destination. Islandbayy cut it too fine and he didn't account for the temperature which caused the pack heater to kick-in; he had two small children in the car in freezing weather but assumed that he was good to go precisely because of all the forum discussions on 8 miles, 10 miles, 14 miles etc. being available in reserve. Kramer driving on zero is funny, in this real life situation we can all be thankful that nothing worse than a lot of cold inconvenience occurred.

[/rant]

Now, here come the PSA's:

1. There's a great thread called Putting-some-numbers-on-the-factors-that-affect-range that is worth reading. It's a sticky in the battery and charging section. Very useful information put together by ChadS.
2. If you do run your traction pack till the car stops, go into the controls screen and power down the car. That way the 12v should retain enough power to wake the car and put it in tow mode even a couple of hours later.
3. If your 12v battery drops below 10v (sorry Islandbayy, this sounds like yours maybe did) it's probably toast in the short-medium term.

Finally, kudos to Tesla for at least trying to help. I can just imagine running out of gas in the middle of the night and calling the automaker asking them for help.

 

[Kalud]

Discussion about what reserve you have below zero is misleading at best and potentially dangerous. The reason that reserve is there is to account for different weather and road conditions; this thread alone proves that the reserve shouldn't be counted on to get you to your destination. Islandbayy cut it too fine and he didn't account for the temperature which caused the pack heater to kick-in; he had two small children in the car in freezing weather but assumed that he was good to go precisely because of all the forum discussions on 8 miles, 10 miles, 14 miles etc. being available in reserve. Kramer driving on zero is funny, in this real life situation we can all be thankful that nothing worse than a lot of cold inconvenience occurred.

[/rant]

I fully agree and don't thing anyone really "count" on those past-zero miles to reach their initial destination. 0 should be treated as 0. In my case, on my first day, I underestimated the effect of cold weather and only added about 20mi of backup in my trip planning and that was the mistake. Then I was so close to home (closest charger at that time) that I tried to... I am pretty sure I won't ever get past zero again.

 

[andrewket]

There is a big difference between a fuel gauge with a think needle on a line that says Empty and a number that says 3 miles left. You have no idea really how far you can go with the ICE but if the EV says three miles then many expect to go three miles even in a snow storm driving up a mountain. Tesla had to account for that so leaving a small buffer is a good idea. You know when you hit zero if could be one mile or ten it you know it is time to pull over and come up with a different plan other than trying to make your destination if it is cold and dark outside.

This is all true. But on the flip side, the energy screen will tell me how much energy I'm using. If I know how much energy I have left and how much I'm using RIGHT NOW, I can make an educated choice. As it stands we have the demand information but not the supply. The bottom line is of course - don't drive below 0. Just don't count on it. Personally I've never driven below zero. But I certainly can understand why people end up doing it. Especially when I'm *just* 3 miles away from the supercharger.....

 

[NigelM]

In my case, on my first day, I underestimated the effect of cold weather and only added about 20mi of backup in my trip planning and that was the mistake.

You made me remember ChadS' excellent piece on accounting for different range influencers. I updated my post above also.

 

[bluetinc]

I liked it better when Tesla did not "hide" range below zero. I understand why they made the change.
[/COLOR]

Andrewket,

This isn't quite true, Tesla has always had a reserve below 0, at least since 4.0 when I received my car, and from some stories I've heard well before then. There may have been a small change with the latest 5.X version that added a couple of miles to it (which I need to verify when the warm weather returns), but it hasn't changed much.

Peter

 

[brianman]

Personally, I liked it better when Tesla did not "hide" range below zero. I understand why they made the change.

Are you talking about the Roadster? For my Signature Model S, zero never meant zero; there was no change here.

 

[dsm363]

This is all true. But on the flip side, the energy screen will tell me how much energy I'm using. If I know how much energy I have left and how much I'm using RIGHT NOW, I can make an educated choice. As it stands we have the demand information but not the supply. The bottom line is of course - don't drive below 0. Just don't count on it. Personally I've never driven below zero. But I certainly can understand why people end up doing it. Especially when I'm *just* 3 miles away from the supercharger.....

That makes sense but only works if Tesla tells you exactly how many kWh are left until the car stops moving. The 'rated range' is too imprecise for that I think. I understand why people go for it too but they should do so knowing they are risking getting stranded.

 

[mknox]

Can someone explain why the Model S can't be towed like this? It can't be the weight since I've seen heavy trucks towed this way too.

 

[ElSupreme]

Can someone explain why the Model S can't be towed like this? It can't be the weight since I've seen heavy trucks towed this way too.

The only reason I can think is that Tesla doesn't want to be liable (or rather just suied) if the car becomes unstable (aerodynamically) under some wind conditions. And causes the dolly to sway. The towing requirements gives them a very good defense.