12v battery low, charge from 12v socket inside the car possible?

[Stormforge]

I was searching for a portable jump starter battery pack in case I ever find myself with a dead 12v battery. Then in occurred to me that I don't need the power to turn a starter motor, just enough to run the electronics. It'll be even more convenient if you can do it from the 12v socket.

Does such a product exist? Is it even possible?

If not, can I just attach a 12v source directly to the battery temporarily?

 

[Cocijo]

I remember being able to trickle charge an old ICE car by plugging a suitable device into the cigar lighter. I’m not sure about starting though - the wiring needs to be of the right thickness - but I guess it could work.
I have a small battery pack that is specifically for 12v car battery jump starting - this is the modern way these days and is quick and easy.
As you say the 12v doesn’t need to turn a heavy engine via a starter motor it just needs to have sufficient power so that the HV pack can get engaged. If the 12v is completely dead you may need to remove the cables to eliminate the battery and then plug in the pack but I’ve not had an issue with my EV 12v. When you say attach a 12v source to the battery do you mean to trickle charge it?

 

[Stormforge]

I'm thinking something like 3x 18650 batteries in a series.

 

[Cocijo]

Ok - they’re about 3.7v each cell? Why do you want to connect them to your 12v?

 

[Stormforge]

Sorry, I wasn't clear. If I ever find my 12v battery flat. I wonder if I supplied the car with 12v from something like these lithium batteries will be enough to get the car started.

I also had a thought about the 12v socket in the car. It's off when the car is off, so I think it's a no go.

 

[Cocijo]

Oh ok. I’d recommend that you keep one of the quick start battery packs in your car if you’re concerned. They’re on Amazon. You don’t need a super powerful one. Amazon product ASIN B08JCYZGYW

 

[Cocijo]

That’s just an example - not necessarily the one that you want btw

 

[Stormforge]

You're right, just a cheap one would do the job and less hassle! Thanks!

 

[Ranger]

Noco do good stuff

 

[macd2401]

One of the starter packs is probably the way to go. Starting current from the 12v battery isn't anywhere near as much as an ICE vehicle, but it's still toasty on the amps. A regular lipo pack likely wouldn't have the grunt to start the car.

 

[Elec Car Aust]

The cig lighter may have a reverse current flow device and as you said without powering up I dought it would work. I bought one of the below but touch wood haven't needed it so far. Has the added benefit of a torch and can charge phones etc. in the tent when camping, which we do a lot. Only weights about 1kg so worth having I think.

SJS 1200Amp 12V Lithium Smart Jump Starter - SJS1200 | Sjs | Shop our Full Ranges by Brand | Autobarn | Autobarn Category | Autobarn

12V 12000MAH LITHIUM JUMP START 1200AMP Overview Jump start MOST vehicles UP TO: 2.8 L DIESEL (2800cc) / 6L PETROL (6000cc) 1200Amp Absolute Cell Power 500Amp Max. Peak Clamp Power 200Amp Max.Start Clamp Power 12v 12,000mAh (44.4Whr) Lithium Polymer Battery Cell 12 month warranty . Conditions...

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