Safe to use old 2.2 Amp yellow-tip adapter to charge T40p?

[alant]

Any electrical engineers here?

The T40p comes with a 4.5 Amp adapter and I have a spare 2.2 Amp adapter. So, I know it will take longer to charge but is it safe to use the 2.2 Amp? I am thinking of leaving the 2.2 Amp attached to the dock, which means it will be on for long periods of time.

If not acceptable, will it be OK for X41? I see that it comes with a 3.5 Amp adapter.

Regards - Alan.

[Kyocera]

Really should not go lower in the amps range, bad for power supply.

[jdhurst]

This question keeps popping up despite all the answers. Ohms law says extra amps = more heat (amongst other things like P=VI). ... JD Hurst

[Thinkpaddict]

Hello,

I would personally never risk a 2K piece of equipment by failing to use a $40.00 adapter. Make yourself a favor and order an adapter from IBM (or Lenovo). The adapters that come with Thinkpads are designed specifically to work on Thinkpads. This is just my personal opinion.

[alant]

Thanks very much. I'll put in the rubbish bin.

[beeblebrox]

Hello,

I would personally never risk a 2K piece of equipment by failing to use a $40.00 adapter. Make yourself a favor and order an adapter from IBM (or Lenovo). The adapters that come with Thinkpads are designed specifically to work on Thinkpads. This is just my personal opinion.

What a nonsense from some pseudo-engineers here in the forum!

Keep that power plug! Just remember, that the output of a Thinkpad plug is 16V. If it can support a continuous current of 2.2A, then its performance is 16V*2.2A= 35.2 Watts.

My T40p runs usually at 10-15 Watts, with max. performance at about 33 Watts. The power plug is just fine.

However, if you have an empty battery, then the power plug is not strong enough to run the notebook at max. performance (100% CPU usage and GPU usage) and at the same time charge the battery as well. The plug would get very hot and turn off after some time. That's only with a empty battery that charges at the same time!

My battery is in the fridge, if I don't use it at home and have multiple small 35 W plug across the house. Never had any problem, just do your math.

[Kyocera]

I say again, because I work in this field, when a device requires X number of amps like a microwave or a fridge, and you lower the amps the power supply starts trying to pull more, this is basic electronics, the device is the load it requires a certain amount of electromotive force, heat in the form of electrons. When you plug two or three power strips into a wall outlet rated at 20 amps, with a fridge, microwave, ac, tv, and the total load on the circuit exceeds the 20amps (pulling more heat in the form of electrons through the copper wire) the breaker pops. These devices are trying to pull more electrons through the wire than it can stand without overheating.

Your laptop is a load, it is looking to pull X amps, if if does not get X amps the power supply, tries to pull more if it does not get it, it will keep pulling until it overheats and trips its own breaker, usually in the form of a little tiny resistor specifically for that purpose. The important part of the equation here is amps. Not trying to debate with beeble but while your math is correct you are simply stating that amps is not relative to the equation, certainly it is. If you look at the AC adapter itself nowhere does it specify watts, it does, however specify amps and volts. Another extrememly important part of this is the pos/neg tip, I have seen many adapters with reveresd tips, this will cause problems as well.To actually consider using a charger rated less amps than specified will ultimately damage the power suppply.

[Thinkpaddict]

Hello,

I would personally never risk a 2K piece of equipment by failing to use a $40.00 adapter. Make yourself a favor and order an adapter from IBM (or Lenovo). The adapters that come with Thinkpads are designed specifically to work on Thinkpads. This is just my personal opinion.

What a nonsense from some pseudo-engineers here in the forum!

Actually I am not an electric engineer (just a software engineer). Thanks for upgrading me to a pseudo-(electric)engineer.
However, please point out the specific statement(s) in my post that were ilogical/nonsense, since I still fail to find them after repeated review.

Like I said in my post, my personal opinion is that I would not cheap out on a power supply for a 2K computer. You don't need to be an engineer to reach that conclussion. It is just common sense.

If you know something about scientific method, you probably will agree that the fact that you have done this before with no serious consequences
doesn't imply that that it is a safe practice. People do stupid things all the time with no consequences (for a while some times), but that doesn't change the fact that they are still stupid.

Thanks for the Kirschoff basics, but I think you are oversimplifying matters. Is the ACME transformer tested to operate under the same load as the Thinkpad? Will it react the same to power fluctuation or spikes?
Why does IBM/Lenovo charge $40.00 for a stupid transformer that I can buy in Radioshack for $10.00? Do you think IBM/Lenovo tell you to use the stock AC adapter because they want your $40.00 when they are selling $3,000 machines? Read Kyocera's post, he seems to know what he is talking about.

Last, but not least, even if you are not cautious enough with your own Thinkpads to use the original adapter, why would you want to give somebody else such poor advice when they are asking for help? What if the guy fries his computer because the ACME transformer fails? What are you going to tell him? I'm sorry, but that never happened to me?

[Kyocera]

I remember when IBM had their own forum, I used to see this question asked all the time, here is the way I explained it once there without all the R/I/E stuff. If you can use a 2 amp adapter for a 5 amp system then why can't you go to radio shack buy a $30 adapter rated at Xv and Xa, find the correct plug/connector and use it. You could save lots of money this way. It will not charge the battery correctly and it will eventually cook the power supply in your computer, which is a pain to replace. Did it on a friends 380ED. Amps is the important thing here. Could you start a car with a 16V laptop battery? Why not it puts out 16V, more than enough V in fact it might actually blow the starter motor with all those volts, correct? You need the amps.