need an Electrical engineer to explain this, jump box Options

[r_towle]

Hi,
I have a 997 (this feels like the start of a support group thing)

This car has an electric front hood latch.
So, the battery needs to be hooked up to open the front hood where the battery is...
Its not logical, but Porsche put in a shortcut.

So, go to the fuse box inside, pull out a red lead, and hook up a 12VDC battery to this lead, and chassis ground...
Hood opens.

Instead of using a full size heavy car battery, I went and bought a lithium battery "jump box" thing
Schumacher SL1639 Lithium Portable Power Pack and 1000A 12V Jump Starter

So, it will not work.
We ended up getting a full size battery, with jumpers, just to open the hood, so we could reconnect the battery.

My question is...WHY does it not work?
When I put my meter on it, I see 16VDC
ITs fully charged.
Its on.

The Tech support told me the unit can only be used for jump starting a car.
The mechanic at the shop told me he also had this issue, and the unit needs to see a load??

I will return this if it will never work...but I really need to know why it won't work.
I can get a motorcycle battery, or some other unit that will take care of my needs...but this thing should work...yet it does not.

Anyone care to explain electricity to me?

Rich

[theer]

Rich- I had the same thing happen to a friend’s 911 (I only run with the crowd owns these fancy-pants cars, don’t have one myself.). Anyway, I used a regular jump pack - the big heavy one- and it worked fine.

I have also used the same jump pack to run the 12v winch on my car trailer. Works fine for that, too. Maybe the little lithium ones have some kind of security/safety BS thing to protect it…?

[Superhawk996]

Maybe the little lithium ones have some kind of security/safety BS thing to protect it…?

The thing everyone loses sight of is that Lithium-ion batteries are not “just” a battery.

Lithium ion batteries are volatile. As such, almost everything except a raw cell has a battery management system to protect them from being fully drained below 10-20% of capacity. Likewise they are protected from over charging. They are protected from short circuits. Lithium-ion batteries can self oxidize (I.e burn) due to thermal runaway if the cell gets too hot from being charged or discharged to fast. This is all done by a microprocessor (and other electronics) controlling the battery. Even single cells can have a very simple battery management system on them.

If the battery management system wants to limit current in or out it can do so. In your case, current is being limited until it sees a load that looks like a battery (connected proper polarity) and a low resistance load like a starter motor.

Not just a battery.


https://lygte-info.dk/info/battery%20protection%20UK.html

Note: mechanical engineer but don’t hold it against me - I play with electrons too!