Jump starting an ICE from a MY

[73Bruin]

Today, I jump started my mother-in-laws Chevrolet Malibu from my MY. I checked owners manual that is available on the system screeen and it gave instructions for getting a jump. If there was a reference to giving a jump or telling you not to do it, I didn't see it. The battery is located under the cover at the back of the frunc. It pops off easily enough and there is (at least on mine).a full size 12 battery. The The positive and negative terminals were clearly marked and it was easy to attach jumper cables. I didnt' see any obvious other places to put the negative jumper on.

The Malibu doesn't have a real big engine so we waited 3 or 3 minutes before attempting to start it. It wasn't the most robust start, but the standard battery in the MY turned the Malibu's engine over and it started in about 3 or 4 seconds. I don't think it would start a big V8 in a truck but the Malibu the Tesla was fine. After disconnecting the cables, the cover was pretty easy to snap back into place. I drove the Tesla about 25 minutes to get home after this and didn't notice any issues.

Did I do anything wrong, that might have harmed the MY?

 

[Mike_TV]

I don't think you did anything wrong. Just a little bit more work to get the maintenance panel removed over an ICE car where you can pop the hood and get access to their 12 volt battery quickly.

 

[Sophias_dad]

Page 195 of the 2021 Model y owners manual...

"Jump Starting the 12V Battery CAUTION: Model Y cannot be used to jump start another vehicle. Doing so can result in damage."

That said, if your car still seems fine it sounds like it was undamaged.

I think there are three reasons to avoid it:

The first is that Tesla's have fairly small batteries that aren't designed to supply the power needs of an ICE starter.

The second is they use a circuit off the HV battery to charge the 12V, and that circuit probably isn't designed for the ludicrous demands of an ICE starting. It might notify the computer that something is TERRIBLY wrong with the 12V battery because its current demand jumped from 1 amp to neigh-infinity in a millisecond.

The third is that once the dead vehicle starts, its going to do its best to get the 12V battery to 14.4V or somesuch, and the computer might notice the voltage rising and raise alarms.


If you need to do a jumpstart again, see if you can do so by linking the two batteries via jumper cables for a few minutes, then disconnect the jumpers(any one of the four ends, really) and then try the dead car. This will reduce the chances of problems in the charging circuit.

 

[Mike_TV]

Page 195 of the 2021 Model y owners manual...

"Jump Starting the 12V Battery CAUTION: Model Y cannot be used to jump start another vehicle. Doing so can result in damage."

That said, if your car still seems fine it sounds like it was undamaged.

I think there are three reasons to avoid it:

The first is that Tesla's have fairly small batteries that aren't designed to supply the power needs of an ICE starter.

The second is they use a circuit off the HV battery to charge the 12V, and that circuit probably isn't designed for the ludicrous demands of an ICE starting. It might notify the computer that something is TERRIBLY wrong with the 12V battery because its current demand jumped from 1 amp to neigh-infinity in a millisecond.

The third is that once the dead vehicle starts, its going to do its best to get the 12V battery to 14.4V or somesuch, and the computer might notice the voltage rising and raise alarms.


If you need to do a jumpstart again, see if you can do so by linking the two batteries via jumper cables for a few minutes, then disconnect the jumpers(any one of the four ends, really) and then try the dead car. This will reduce the chances of problems in the charging circuit.

All good points and I missed that part in the owner's manual. I guess if you wanted to be a friendly Tesla owner to others maybe we should carry one of those portable lithium ion jump-starters to help others out. That'll eliminate the need to open up the maintenance panel and prevent any damage to the car.

 

[Johnny Vector]

All good points and I missed that part in the owner's manual. I guess if you wanted to be a friendly Tesla owner to others maybe we should carry one of those portable lithium ion jump-starters to help others out. That'll eliminate the need to open up the maintenance panel and prevent any damage to the car.

Those little Li-ion jump-starters are kind of amazing! I got one when I still had my Fit that came with a too-small battery that was low on water in one cell (I generally like Carmax, but they don't always fix all the leftover stupidity of the previous owner). The jump-starter worked great the one time I needed it. So now I carry it in the Tesla. Takes up a tiny bit of the shallow sub-trunk, and is just always there if I, or anyone else, need it.

 

[CapsEngineer]

Those little Li-ion jump-starters are kind of amazing! I got one when I still had my Fit that came with a too-small battery that was low on water in one cell (I generally like Carmax, but they don't always fix all the leftover stupidity of the previous owner). The jump-starter worked great the one time I needed it. So now I carry it in the Tesla. Takes up a tiny bit of the shallow sub-trunk, and is just always there if I, or anyone else, need it.

I bought two of those, one for my car and one for my wife’s Lincoln hybrid after our daughter in law called for help when her car wouldn’t start. I took the jumper cables with me and on the way there remembered that I wouldn’t use my car, but I figured with cables in hand someone would help. Then I did a little research before buying mine jump-starter and found out you shoudn’t use a hybrid either.

Also gives you a HUGE pack for charging your phone.

 

[jcanoe]

I have had a good experience using a small lithium battery jump starter. I keep a jump starter at home and a second jump starter in the Tesla. The one in the Tesla is primarily for jump starting other vehicles because if my Tesla Model Y's 12V battery suddenly dies without warning I won't be able to unlock the Tesla to get to the jump starter.

I don't think that leaving a lithium battery jump starter in any vehicle in summer heat is good for the life of the jump starter battery. I keep the jump starter from the Tesla inside my home until the end of summer.

 

[maus92]

Today, I jump started my mother-in-laws Chevrolet Malibu from my MY. I checked owners manual that is available on the system screeen and it gave instructions for getting a jump. If there was a reference to giving a jump or telling you not to do it, I didn't see it. The battery is located under the cover at the back of the frunc. It pops off easily enough and there is (at least on mine).a full size 12 battery. The The positive and negative terminals were clearly marked and it was easy to attach jumper cables. I didnt' see any obvious other places to put the negative jumper on.

The Malibu doesn't have a real big engine so we waited 3 or 3 minutes before attempting to start it. It wasn't the most robust start, but the standard battery in the MY turned the Malibu's engine over and it started in about 3 or 4 seconds. I don't think it would start a big V8 in a truck but the Malibu the Tesla was fine. After disconnecting the cables, the cover was pretty easy to snap back into place. I drove the Tesla about 25 minutes to get home after this and didn't notice any issues.

Did I do anything wrong, that might have harmed the MY?

Yes, you did something wrong - it states in the Owner's Manual not to use the 12v battery to jump start other vehicles.

 

[FloridaSun]

Those little Li-ion jump-starters are kind of amazing! I got one when I still had my Fit that came with a too-small battery that was low on water in one cell (I generally like Carmax, but they don't always fix all the leftover stupidity of the previous owner). The jump-starter worked great the one time I needed it. So now I carry it in the Tesla. Takes up a tiny bit of the shallow sub-trunk, and is just always there if I, or anyone else, need it.

I have one of those Lithium jump starters. They work fantastic!

 

[73Bruin]

Yes, you did something wrong - it states in the Owner's Manual not to use the 12v battery to jump start other vehicles.

Since Sophias_dad already posted a much more detailed and nuanced reply, did your really add anything?

 

[maus92]

Since Sophias_dad already posted a much more detailed and nuanced reply, did your really add anything?

Not really - just like your comment.

 

[TomServo]

When a Mobil Tech installed my HomeLink I had a chance to snoop around the naked FRUNK and was surprised how SMALL the 12V battery was as compared to an ICE vehicle.

 

[Casey1956]

Page 195 of the 2021 Model y owners manual...

"Jump Starting the 12V Battery CAUTION: Model Y cannot be used to jump start another vehicle. Doing so can result in damage."

That said, if your car still seems fine it sounds like it was undamaged.

I think there are three reasons to avoid it:

The first is that Tesla's have fairly small batteries that aren't designed to supply the power needs of an ICE starter.

The second is they use a circuit off the HV battery to charge the 12V, and that circuit probably isn't designed for the ludicrous demands of an ICE starting. It might notify the computer that something is TERRIBLY wrong with the 12V battery because its current demand jumped from 1 amp to neigh-infinity in a millisecond.

The third is that once the dead vehicle starts, its going to do its best to get the 12V battery to 14.4V or somesuch, and the computer might notice the voltage rising and raise alarms.


If you need to do a jumpstart again, see if you can do so by linking the two batteries via jumper cables for a few minutes, then disconnect the jumpers(any one of the four ends, really) and then try the dead car. This will reduce the chances of problems in the charging circuit.

Owners Manual for my Prius said leave the jump cables connected for 30 minutes or so, to let the recipient ICE battery take a good charge. But then, as you suggest, disconnect the jumpers BEFORE attempting to start the ICE to preclude a current draw that might fry the Prius's innards. Some concept for a Tesla, I assume. (And a sore point with both Prius and Tesla: surely there's a scheme they could build in to tap a sliver of all the energy stored in the traction batteries for the trivial task of recharging the 12-v battery!)

 

[Sophias_dad]

Owners Manual for my Prius said leave the jump cables connected for 30 minutes or so, to let the recipient ICE battery take a good charge. But then, as you suggest, disconnect the jumpers BEFORE attempting to start the ICE to preclude a current draw that might fry the Prius's innards. Some concept for a Tesla, I assume. (And a sore point with both Prius and Tesla: surely there's a scheme they could build in to tap a sliver of all the energy stored in the traction batteries for the trivial task of recharging the 12-v battery!)

Yes, that would be how to do it with a tesla as well.

The reason they would NOT bother to tap a sliver of all the energy in the traction batteries is MONEY. There's really not much upside for Tesla.


What does Tesla get out of it? Maybe getting to start an ICE car once in a while. Maybe the occasional super-meltdown when someone connects the 12V lines backwards, and Tesla will be expected to cover that under warranty.


What does it cost? Tens or even potentially low hundreds of dollars per car in the assorted DC-DC converter parts to get the ~400 volts available from each module down to 12-14 volts, get that power through many dollars per foot cabling from under the back seat to up near the 12V battery, and so on. I for one would much rather have free homelink in every 3/Y that around half the users will want than the chance to jumpstart an ICE every now and again.

 

[drtimhill]

When a Mobil Tech installed my HomeLink I had a chance to snoop around the naked FRUNK and was surprised how SMALL the 12V battery was as compared to an ICE vehicle.

well it doesnt have to crank a huge mechanical V6 engine is why