Thinkpads Forum

I recently purchased a W510 which I now realize should have come with a 135W power adapter.

I initially thought I would need to purchase one ($50+). But then I thought of an idea: I have many 90W and 65W power supplies around. Could I just splice two 65W adapters together? (65+65 = 130).

I have enough adapters that I don't mind sacrificing two. But could I damage the laptop?

sbddude wrote:. But could I damage the laptop?

I've spliced copper.

I've spliced fiber.

Never in my life have I spliced two adapters together nor would I ever advise anyone to do so even as a joke.

Lol, you can just as well use the 90 W for the W510, but you'll need to mod either the adapter or the notebook to fool the W510 into thinking the 135 is connected. More info on the "170 W for W520" thread.

I did the mod to the laptop but it only works while undocked. When docked, it still detects that a 90W is attached.

How does one mod the 90W to appear as 135W?

It's DC output, not AC, so I don't see why you couldn't wire two of them in series PARALLEL. I can't say whether or not the machine would see it as a larger power supply due to the signal pin, though.

Edit - Fixing mental lapse lest someone follow my very wrong advice.

EasyMac308 wrote:It's DC output, not AC, so I don't see why you couldn't wire two of them in series.

That would be a MAJOR mistake as the combined voltage would then be 40V and you'd probably blow up your system, assuming the supplies didn't smoke first. What you probably mean is PARALLEL; + to + and - to -. That way the voltage remains the same (20V) but you would get the benefit of doubling the current capability to 6.5A or 130W. However, it's debatable whether or not the power supplies will even allow you to do this. As George says, I wouldn't suggest it.

rkawakami wrote:

EasyMac308 wrote:It's DC output, not AC, so I don't see why you couldn't wire two of them in series.

That would be a MAJOR mistake as the combined voltage would then be 40V and you'd probably blow up your system, assuming the supplies didn't smoke first. What you probably mean is PARALLEL; + to + and - to -. That way the voltage remains the same (20V) but you would get the benefit of doubling the current capability to 6.5A or 130W. However, it's debatable whether or not the power supplies will even allow you to do this. As George says, I wouldn't suggest it.

Of cours,e I would wire them in parallel. Why wouldn't the power supplies allow this to be done?

Cut both of the wires on the DC side, connect together, and then connect one barrel connector on the end.


AC > [PwrAdapter1] > DC > {splice here} > [thinkpad DC power connector]

Every PSU has a slightly different voltage; on top of that you have different wattages. That would call for some sophisticated load leveling. Buying a new power brick is much better idea.

Wow, you're right. Totally my bad, I meant parallel. Stupid brain.

sbddude wrote:I did the mod to the laptop but it only works while undocked. When docked, it still detects that a 90W is attached.

How does one mod the 90W to appear as 135W?

90 W adapter appears to have no connection between pin and ground, 135 W adapter apparently has a direct connection.

So connecting the pin of the 90W to ground should make the laptop think a 135 is connected.

It should also be possible to mod the laptop for the docking scenario

However, in case of docking the weight and size of the brick is largely irrelevant and since a matching brick is supplied with the laptop, most modders just leave the supplied brick at the dock while taking the smaller ones on the road.

There's just way too many complications that arise from just simply wiring up two different power supplies for a combined wattage rating, to power a laptop. If anything, I'd combine two of the same power brick if I was at all planning to attempt it. Only reason I would is just for screwing around.

If it's for an ACTUAL laptop that you plan to use, even bringing up the idea to me is a big NO. Even if you think you know what you're doing, you could damage your laptop. As much as modifying current parts to create something that works better is always an awesome field of innovation(such as whatever absolute genius thought to plop a T61p motherboard into a 15" T60p case), this is electricity you're working with. So much can go wrong.

So...long story short, it only partially works.

I connected the two bricks together and used diodes to isolate the supplies from each other. The combined output is detected by the laptop and charges, but SLOWLY. It seems like slower than one 65W alone. I also noticed that one of the two adapters is hot (like normal) and the other is cold. So only one is actually powering.

So I will be converting back to single-use and looking for a cheap 135w on ebay.

Wow. Interesting that one adapter still takes the heat... and it would charge that much slower. Thanks for reporting back since you actually tried it-that's really weird that it ends up working like that.

"I connected the two bricks together and used diodes to isolate the supplies from each other. The combined output is detected by the laptop and charges, but SLOWLY. "

That is to be expected, since even the finest low-loss diodes would probably drop the voltage about .3V from each supply, and the lower voltage will be noticed by the laptop.

Somewhere there's a fine thread that someone referred me to, about how each different power adapter has a different "signal" resistor built into the tip, with a third contact, to signal the laptop what it is. The laptop may complain--as my 530 did when I plugged in a 90W supply--but as long as the supply is providing more power than your laptop is sucking down, you can ignore that. If you are loading up the system and drawing lots of power (full screen brightness, max cpu usage, two spindles rotating, etc.) and you've got a discharged battery that is also trying to suck power, sure, you want the full rated power supply. If you're only doing half of that, drawing half the rated power, you don't need that much at all.

But power supplies these days are all digital electronics inside, and they are not meant to be wired into each other. I'd be real reluctant to guess the clever ways they might find to misbehave when connected that way. I'm a cheap, ergh, tight SOB but I'd just shop around for ONE proper supply. A kludge just isn't something you want to rely on, is it? Considering the cost of the equipment hanging off it?

--Red

You may ignore the message... but the notebook won't do anything with the adapter and just drain the battery.
And yes, that thread was already advertised here... by me... in the 3rd message in this thread.

Dunno, jc. I had my old 90W adapter plugged in for a good hour or longer, and the battery stayed at 99% and no message came up until after I suspended and resumed the system some time later. Battery was still at 99%, where it usually is.

But I also know the power manager software on this computer is glitchy, I don't understand how Lenovo still gets it wrong after all these years of practice. (I change "on event, lid, behavior and it flushes away the changes instead of making them.)

Perhaps that changed from W520 to W530.

Yeah, I got the same trouble. I want it to ignore lid activity completely... but no joy. It doesn't go in sleep when I close the lid (as set), but it does resume when I open the lid..

Worse is that it resumes when you unplug a headset. Who came up with that idea