Can I/Should I/Jump-start an ICE battery with my Model 3?

[heartfeltsong]

A friend's internal combustion engine (ICE) battery was dead due to a cab light left on, so she asked me to charge her car battery. I found a video on-line (NOT from TESLA) and found the Model 3 terminals under the front hood/frunk:

but wasn't sure if this is recommended:
Here's How To Jump Start Another Car With Your Tesla Model 3 .

What does TESLA recommend?

 

[cwerdna]

I wouldn't.

See Jump Starting | MotorWeek, Jump Starting | MotorWeek and this cautionary tale: Jumping another vehicle - My Nissan Leaf Forum.

 

[NathanielHrnblwr]

Nope. The last thing I'm going to do is interconnect someone else's electrical system with my Tesla.

 

[Feathermerchan]

Get one of those small jump starter batteries on Amazon. You can use it on your Tesla and you can help others without risk of damaging your car.

 

[jdcollins5]

I would not think the Tesla battery is rated to turn over an ICE starter motor. I know Toyota warned against this with the Prius battery for the same reason. You could also damage some internal electronics if jumper cables were misconnected.

 

[notAnExpert]

The “Instructions for Transporters” section of the Tesla Model 3 Owners Manual says:
Caution: Model 3 cannot be used to jump start another vehicle. Doing so can result in damage.

 

[heartfeltsong]

The “Instructions for Transporters” section of the Tesla Model 3 Owners Manual says:
Caution: Model 3 cannot be used to jump start another vehicle. Doing so can result in damage.

Thanks--I looked for this in the manual, but didn't see it.

 

[heartfeltsong]

Get one of those small jump starter batteries on Amazon. You can use it on your Tesla and you can help others without risk of damaging your car.

Thanks--I think I'll suggest that my friend get one of those!

 

[wdolson]

The 12V system on a Tesla is rather weak compared to ICE. It's only there to keep the electronics running and doesn't need to deliver high current to turn a starter like in an ICE. Of course the main battery pack has enough current, but the voltage is incompatible (as well as being inaccessible).

With my old Buick it took me a couple of months sitting in the driveway before I got around to getting it sold. I got one of those starter battery packs to jump start the car when I forgot to start it and run it once or twice a week. They work pretty good and can be used for other purposes like recharging a cell phone during a power outage.

 

[Feathermerchan]

"The 12V system on a Tesla is rather weak compared to ICE."

Not true! Our cars all have power steering on the 12V bus. That can take a lot of power.
The system is run by a converter connected to the main battery. It may be capable of many Amps but not necessarily enough to start a V8. If the current draw gets too high, it limits the output or may even shut down.

 

[miimura]

In an emergency, I would do it. However, I would follow the advice in the InsideEVs story linked above.
"It says if you must jumpstart with a Tesla you should let the Tesla charge the opposite car and disconnect before attempting to start."

 

[derotam]

"The 12V system on a Tesla is rather weak compared to ICE."

Not true! Our cars all have power steering on the 12V bus. That can take a lot of power.
The system is run by a converter connected to the main battery. It may be capable of many Amps but not necessarily enough to start a V8. If the current draw gets too high, it limits the output or may even shut down.

There is a difference between jumpstarting a car and charging a battery. You could definitely use the Tesla to recharge someone's battery but that doesn't mean it has enough Cold Cranking Amps to jumpstart a car with a very dead battery.

Anyone know the CCA rating on the Tesla 12v battery?

 

[jdcollins5]

Charging another vehicle’s battery takes a long time if it has been discharged by lights on, etc. I tried this with my Prius and after 15 minutes and removing the jumper cables, the other vehicle starter would barely click. We flagged another friend to jump him.

 

[voip-ninja]

If you want to help out motorists in such situations do yourself a favor and purchase a lithium ion jump starter from Amazon for $30 and keep it in the car for such uses.

 

[eprosenx]

There is a difference between jumpstarting a car and charging a battery. You could definitely use the Tesla to recharge someone's battery but that doesn't mean it has enough Cold Cranking Amps to jumpstart a car with a very dead battery.

Anyone know the CCA rating on the Tesla 12v battery?

Just like on the Prius I would aaaume the Tesla has a deep cycle battery and not one with much in the way of cold cranking amps as the Tesla does not need CCA (neither does the Prius since the starter runs on the main battery).

I am curious how bad jumping another car off a Tesla would be. When first connecting the terminals the Tesla 12v battery would try to equalize with the dead cars battery. This would drag down the 12v battery and presumably the DC to DC converter that keeps the Tesla battery charger would fire up and flow its maximum rated current? I presume it is self limiting and would cap out at some amperage?

Leaving it hooked up when trying to crank the ICE engine would be interesting as well. I think often times folks don’t realize how much of the starting effort of the ICE is still coming from the discharged battery or from the energy that was transferred to it after hooking it up but before trying to crank it. Unless you are trying with a dead flat battery, it only takes a little current to push it over the edge to start the ICE. Most jumper cables have really bad connections and can’t actially flow that much current.

So yeah, until we know more, I would avoid it, though there are a lot of things Tesla says not to do for no clear reason that folks regularly do anyway. (charging off a generator being one of them)

Note that the main difffernce between start batteries and deep cycle batteries is the thickness of the plates. The start batteries have more thinner plates which improves starting current, but makes them more fragile. Deep cycle have thicker plates but not as much CCA.

FWIW, I could see that dragging down the 12v bus during ICE cranking could cause unintended behaviors to Tesla electronics depending on a stabile 12v source. Probably just easier for Tesla to say not to do it than to actually test.