Question about AC adapter (T410) 65W vs 90W

My T410 is the integrated graphics model, which has the 65 watt AC adapter. I've read that if you run a thinkpad with the battery removed, the system will downclock itself. So I was wondering, do you think I can run with a 90 watt adapter (for the nvidia model) without a battery, would that prevent the system from downclocking? And would it be dangerous?
It's just that I hate to have a battery installed that I will never use. It's bad to keep a battery fully charged all the time, yet cycling it wears it out. I'd rather not have one plugged in at all since my T410 is desk bound anyhow.

 

I've got both a 65W brick (came with my integrated T510) and a 90W brick (which I ordered separately since I wanted a separate power brick anyway) at home. I can try it out for you to confirm that it doesn't throttle when using the 90W with no battery. I'm pretty sure I remember reading that that was the case, but I've yet to try it. I'll try to remember tonight.

 

Thanks mutnat, I'd appreciate it.

 

To the question, would using a 90W adapter be dangerous, the Series 3 docks for the T410 ship with a 90W adapter. My guess is nearly all 90W could be available to the T410, so my next guess is it would be ok.

 

Using the 90w adapter is perfectly safe. However, I'm not sure if it is an effective workaround for the downclock without battery problem (I'd guess yes, but I haven't confirmed).

Additionally, have you tried using the battery thresholds in power manager? You can set the battery to stop charging well below 100% and substantially reduce the cycles as well. If you almost always use it at your desk thresholds such as start at 30%, stop at 50% should work quite nicely (±10% from the ideal 40% long term storage mark). This also gives you the advantage of a built in high quality UPS.

 

Seeing as my T500 doesn't downclock without a battery and using the 90W adapter, I doubt the T410 would downclock with the same adapter (if anything, the power usage is lower). It's perfectly safe, in fact, you could technically use the W510's 135W power brick with the T410 and there would be no issues.

 

I don't see a reason why system clocks down itself when you remove the battery. A T410 consumes about 35w at peak, and the 65W adapter can serve it well.

65w and 90w are max power adapters can give, and for T410, I see it perfectly safe to use either one. The differences, IMO, are, 90w adapter can charge faster and may be slightly cooler.

 

@mike5065, jonlumpkin, midnightsun; thanks, that's good to know.

@vimvq1987, the thinkpads do normally downclock the processor in the absense of a battery. The battery is used to supplement any spiked power requirements in case the AC adapter can't provide enough. I'll see if I can find a link.

Edit: According to one guy (post #15), that's exactly what happens. Link.

And this one especially at thinkwiki.

But I remember reading about this somewhere else, might have been NBR, can't remember.

 

I had used a XPS 1730 with 130w adapter. One day, the adapter died and the laptop couldn't boot up even with a 90w adapter. The bios said something like "This laptop requires a 130w adapter...". I doubt that Thinkpads will also not boot up if adapters can give enough power to them, so "The battery is used to supplement any spiked power requirements in case the AC adapter can't provide enough." seems to be unreasonable. The adapter must provide both power for the laptop to run and for the battery to charge. Just my opinions.

 

I guess Mutnat forgot.

 

@talin: have a test myself, and, this is the result:

 

do you get the max cpu clock if you select "highest" in the max cpu speed in power manager?
my t410 with 3100m will clock 2.9ghz, without battery, in that setting

 

Sorry I was so tired last night even the Vancouver Canucks playoff game couldn't keep me awake and I fell asleep on the couch.

 

Thanks vimvq1987, but that's with a core 2 duo. A core i system (specifically the T410/510) might have different results.
@Mutnat, that's ok. If you can ever get around to it, I'd appreciate it very much.

 

Okay I did some fairly unscientific tests. I was going to try wPrime that I've seen people use to push the CPU, but it doesn't seem to run on my system. (Maybe it isn't compatible with a 64-bit OS?).

Anyway I ended up downloading a trial version of the most recent PassMark performance test 7.0 (1013) for Win64 and tried a few scenarios.

I took the battery out, plugged in the 90W adapter, and ran the suite. While it was running, I watched all four logical cores (2 physical with HT) in Task Manager, and I used the Intel Turbo Boost Monitor Windows Gadget to watch Turbo Boost. During most tasks except the disk tests, I saw Turbo Boost kick in for most of the time. My i5-540M has a base speed of 2.53GHz, and can turbo up to 3.06GHz under single-core load. During theses tests with the 90W adapter and no battery, I saw Turbo vary from none all the way up to a 2.93GHz peak. I forget the exact overall test mark, but it was in the 990's. It was unable to run one test since my integrated graphics doesn't support it, and I skipped the optical test as I didn't have a disc handy.

So then I hibernated, swappwed to the 65W adapter, still no battery. I resumed from hibernation and re-ran PassMark. I didn't let it get to the end, so I don't know what the score would have been. However, through tons of CPU-intensive stuf, the Turbo Boost monitor never once showed any turbo activity. I didn't run any more sophisticated speed gauge, but sufiice it say that the CPU maxed out at the base 2.53GHz using the 65W adapter and no battery.

I then hibernated again and switched back to the 90W adapter with the battery installed. I re-ran the tests and got very similar results to the 90W/no-battery scenario. The Turbo monitor maxed out at 2.93GHz, and the final score was 1004, just slightly higher than the no-battery score. I didn't run multiple passes of any scenario, so I think the two marks can be considered essentially the same.

Oh, all these tests were run using the Maximum Perormance profile, without any tweaks (i.e. the way the profile comes out of the box in Power Manager 3.20).

So yeah it seems that you can get full performance out of an integrated T510 (and presumably T410) without a battery when using the 90W adapter, but not with the 65W adapter.

 

Thanks a lot Mutnat! I appreciate it very much. I'll get the 90 watt adapter now. I'd much prefer to buy a true UPS unit with an integrated surge protector, then use up the battery for my T410.
Thanks again. I'll give you rep tomorrow when I can give out rep again, I've given out too much already today and the system wont let me.

 

No worries, it only took 20 or 25 mins to do. I'm glad I could help. Cheers!

 

I think the T410 will complain if you have discrete graphics while using a 65W adapter, but it shouldn't if you have just integrated.

If you have integrated, the only limitation I'm aware of for a 65W with a T410, is that you have to use the 90W on the docking station.

Btw, Turbo Boost speed is very dependent on the temperature of the CPU. If it's too high, Turbo Boost won't go to it's max speed. Also I think the 3.06 is the max speed if only a single core is used.

 

I have the same processor as Mutnat (i5-540 2.53GHz), and integrated graphics. This should work nicely.

 

Probably the reason why they sell the Series 3 with the 90W (it's not optional, you have to get it, afaik). My T510 with integrated shipped with the 65W, with no option for the 90W for me at the time. The discrete has the option. Looking to pick up a Series 3 dock now. Having the extra adapter is no longer an issue for me, so time to shop.

@hceuterpe, does the dock force the use of the 90W, or is this just recommended?

@matnat thanks for running this test.

 

I would think it needs the 90W since it is doing double duty. It needs to power/charge the laptop and power ports in the docking station. Physically, you could use the 65w as it is external and obviously they both have the same tip.

 

Oh, no if you use ANY dock (or at least any I've heard of and not just Lenovo) you have to use the power supply equal to or greater to what shipped with it. With my Dell at work, if you plug a 65W adapter in it, I don't think it will even let you go past the boot screen. If you yank out the adapter, the ports stop working. I assume the same happens if you do a switcharoo with a 65W. I've never bothered forcing a 65W adapter 'cause I know it won't work, but I assume the same thing would happen. HP EliteBook docks I think are even more picky.

 

When you say external, does this mean I would continue using the adapter plug for powering and charging the ThinkPad as usual? The dock doesn't provide power through the ports on the bottom?

Thanks both for your responses. Sorry to hijack this thread (call it my flash sideways).

 

The adapter is the standard 90W adapter, same as you would get with a T510 with discrete graphics. It is external to the dock, but does plug into the dock, not the computer. The dock then supplies power to the computer (and itself).

 

Thanks. I'll get one then.

 

Uh, if you buy a docking station new, it's supposed to come with a 90W adapter automatically. It sounds like you think you need to buy a seperate adapter (which you don't)

 

No worries.

LOST fan? Me too.

 

No, I just don't like retiring the 65W that shipped with my T510.

 

I think it's great to have an extra adapter. The 90W sits permantly behind my desk connected to the dock. The 65W (which is nice and small) gets stowed in my bag for whenever I need it with me. I save the disconnecting and packing up whenever I take the computer with me.

.

 

You could always buy an external battery charger (40Y7625). These are definitely useful if you ever decide to get the slice battery, as if you're docked, it's the only way to charge it. I find the slice battery to be a useful way to extend runtime , despite the fact that I wish it was flatter/more plate shaped like the Dell slice battery.

Lenovo jacked up the price of it when the new thinkpads came out early this year. I suspect they figured they could make more money by raising the price. They use to sell it for super cheap. I got 2 brand new for around $65. It seems painful paying nearly $100 now for one. If you look though, it seems like you can find some in a surplus sale on some mega-sized auction site...

 

Yeah that's pretty much what I've done, thrown the 65W adapter (the lighter one for travel) into my laptop backpack for use on the road (not that I need to do that often, but still).

 

Mine's a couch-top, mostly always on batteries. I don't even have a bag. I use it for

when I watch commercials during Lost I never watch TV without it. I'll be buying a dock and retire the OC'd desktop--I am still very surprised just how fast these machines are. I'll use the 65W for travel too.