DIY Dell Car charger

[shovenose]

Re: DIY Dell Car charger

OK. Well I can get it for $10 (if it works). Plus the cost of shipping. But I can trade for that RAM for my Toughbook. So you only pay cost of shipiing.

[ratdude747]

Re: DIY Dell Car charger

want the inverter if it works and it's still there next saturday?

depends on a lot... cost (incl. shipping), condition, legalities (who owns it at the moment), etc.

if it is, send me a PM and then I can say more.

[shovenose]

Re: DIY Dell Car charger

want the inverter if it works and it's still there next saturday?

[ratdude747]

Re: DIY Dell Car charger

You sure? There's an extra 140W tripp-lite car to 120V inverter sitting around work :P

well, I'll be honest, I recently aquired a project bicycle that I am busy working on restoring/modernizing (a mix of both)... and I am saving up for new laptop battery, since that would do a lot more then than a car charger would... now if a decent inverter showed up for cheap then it would be different... but right now the time nor funds are not there.

[shovenose]

Re: DIY Dell Car charger

You sure? There's an extra 140W tripp-lite car to 120V inverter sitting around work :P

[ratdude747]

Re: DIY Dell Car charger

Just get the $20 100W car inverter (its safe and isnt going to blowup your laptop) just dont be a noob and overload it trying to run a hairdryer or something on it. The 70W you have is too weak don't use it. Your not going to be able to build anything that is worth a crap for less than $20.

consider this thread moot at this point... other projects and other things put the car charger concept out of the current plans...

[brethin]

Re: DIY Dell Car charger

Just get the $20 100W car inverter (its safe and isnt going to blowup your laptop) just dont be a noob and overload it trying to run a hairdryer or something on it. The 70W you have is too weak don't use it. Your not going to be able to build anything that is worth a crap for less than $20.

[lmcancu]

Re: DIY Dell Car charger

The laptop will work without the chip, however depending on the laptop it will work at half the CPU speed and will not charge the battery. If its being temporarily used in the car it might be an ok tradeoff.

[KeriJane]

Re: DIY Dell Car charger

my friends dell power adapter has the STUPID chip too.
Why on earth could they not put a vsense circuit in instead, volt too high no charge simple.
but i suppose they don't want other adapters to catch fire from overloading???

I suspect the answer to the "Why they put it in there" question is:

1- Dell wants you to buy adaptors from them ONLY so they don't have to compete with off-brands, or

2- Dell has had one too many laptops returned for warranty work with damage caused by an aftermarket charger, or

3- Dell has had one too many inane "Customer Support Sessions" from people using non-Dell chargers and for some reason this caused the laptop to misbehave.

I bet it's reason #1

[b700029]

Re: DIY Dell Car charger

Interestingly, there are tons of Chinese PA10 knockoffs on Ebay, I wonder what they used to to the ident on the centre pin....

It's easy to clone ID chip contents, and blank chips are $0.28 each (real one from Maxim, maybe they already have their own clone of it since 1-wire EEPROM is used in many other things like some ink cartridges) so it is not a real problem.

[smason]

Re: DIY Dell Car charger

my friends dell power adapter has the STUPID chip too.
Why on earth could they not put a vsense circuit in instead, volt too high no charge simple.
but i suppose they don't want other adapters to catch fire from overloading???

It's more about the current it can produce. I can use 90w supplies in any Dell notebook at work, but the 65w will only work in the smaller notebooks.
When a full-size laptop like an E6500 is used with a 65w supply, you get a warning, and the system goes into a low power mode.

Interestingly, there are tons of Chinese PA10 knockoffs on Ebay, I wonder what they used to to the ident on the centre pin....

[riotpack]

Re: DIY Dell Car charger

You can do it if you have enough time and enough test gear and the brains to pull it together. Start with the controller IC, for instance http://www.ti.com/lsds/ti/analog/pow...er_portal.page has a easy to use page where you input the Vin and Vout and Iout and it suggests the tps40210 IC.

So you download the datasheet and if you haven't built a DC-DC switching boost converter before you should download DC-DC design guides as well as be competent in magnetics such as inductor characteristics (you can wind your own, the formula is L = Nturns(sq)*Permeability of the magnetic circuit * CSA of the magnetic circuit in SQ meters / (inversely proportional) to the length of the magnetic circuit).

That formula is basic for a cylindrical coil, but that is the least of your worries as lets get input spike protection sorted and overcurrent protection when the car is being started and Vin is low so Iin is increased to compensate increasing your I2R losses through the entire design of the primary stage. Pick a switching frequency, the data sheet explains how, and choose soft start values, but not too a slow ramp up or the laptop will see an under voltage and may not want to charge.

May be easier to buy one, or may be the time to experiment with simple step up and step down switchers. the MC34063 or the old TL494 are great fun to play with! and eventually you will obtain the confidence to hook an expensive laptop to your design....

[joshnz]

Re: DIY Dell Car charger

my friends dell power adapter has the STUPID chip too.
Why on earth could they not put a vsense circuit in instead, volt too high no charge simple.
but i suppose they don't want other adapters to catch fire from overloading???

[momaka]

Re: DIY Dell Car charger

I've fixed a genuine 90W Lite-ON -based PA-10 power adapter for a friend, and it had only 2 wires going to the plug - 1 for ground and 1 for V+. Unless the plug had a chip inside, I don't see where else it would have been.

[b700029]

Re: DIY Dell Car charger

Yes, the identification signal is provided by small EEPROM inside the adapter:
http://www.laptop-junction.com/toast...stery-revealed

This chip can be moved inside the laptop to allow any voltage source to work.

[ratdude747]

Re: DIY Dell Car charger

keri, you answered a key question regarding the signal pin.

if it really is complex signal sent (not a voltage or short), then that does indeed kill the project.

Am I still correct not to use the 70W inverter from this:

https://www.badcaps.net/forum/showth...ght=vector+70W

the documentation on the adapter made it sound like it was not a square wave unit, but it could have been BS. I do know a 60W brick made it dangerously hot... so my guess is that it is trash?

[KeriJane]

Re: DIY Dell Car charger

Don't Dell laptops generally have a 3-wire adaptor with a data signal to indicate what type of charger is being used? That could make DIY a little tricky unless you gut a Dell charger for the parts. The last Dell laptop I worked on had a problem with the DC jack and wasn't acknowledging the charger until I replaced the jack.... Even with 19v on the board, it wouldn't charge unless it can detect a genuine Dell charger.

A moderately decent 120v inverter is probably the best way to go.

Good luck, have fun with your project.

[ratdude747]

Re: DIY Dell Car charger

it was both a side project and a pratical project.

[weirdlookinguy]

Re: DIY Dell Car charger

You're overthinking this. $60 isn't that much if it's something you really need (I'm talking about the universal car adapter).

The homebrew solution will be extremely clunky and a pain in the ass to plug in every time you want to use it which means you'll use it less. When all is said and done I'd be willing to put down money that the total for a homebrew will come close to or exceed the cost of a real universal adapter.

If you want to make the homebrew as a fun side project (you are an EE major after all), go for it. But if it's for practical purposes then just buy the real thing and carry on with life. Shit like this is not worth stressing about.

[ratdude747]

Re: DIY Dell Car charger

Lol, my $20 harbor freight inverter ran a few different laptops just fine.

luck is never a good reason to do something. if you cannot find a lovical reason, don't do it.

I have this thing still:

https://www.badcaps.net/forum/showth...ght=vector+70W

but i don't want to burn down the car or the laptop.