Compatibility of older Thinkpad AC adapters with T42?

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Kenn · #1 Post by **Kenn** » Thu Jul 22, 2004 10:31 pm

I have a few older Thinkpad AC adapters, and the specs are off enough for me to worry about damaging the thinkpad or the battery if I used them.

The T42 ships with FRU 08K8209 AC adapter (nowhere to be found on IBM's site, they call for replacement FRU 02K6699):
Input 100-240v, 1.9A, 50-60Hz
Output 16V, 4.5A

My old AC adapter:
FRU 02K6555
Input 100-240v, 1.3A-0.7A, 50-60Hz
Output 16V, 3.36A, same polarity

FRU 11J8956
Input 100-240V, 1.3A-0.7A, 50-60Hz
Output 16V, 3.36A, same polarity

I assume the variance in Input isn't a big deal, but does the 3.36A v. 4.5A output mean anything? Will this cook the machine completely or ruin the charging cycles on the battery? Is it OK to run? Hoping someone with some electrical experience can enlighten me on what is probably a silly question.

Leon · #2 Post by **Leon** » Thu Jul 22, 2004 11:23 pm

NO! Do NOT use the others. At best, it can cause instability with your motherboard. If you need extras, get them cheaply here. Many from this board have bought them here.. I bought 5!

http://stores.ebay.com/DFW-Boxes

Kenn · #3 Post by **Kenn** » Thu Jul 22, 2004 11:45 pm

Thanks. I've seen that dealer but haven't bought from them before. Did you ask regarding the input/output specs of the adapter before you bought? Can I ask if the specs for the 5 you purchased exactly match the 16V/4.5A as on the included T42 AC?

Thanks!

Leon · #4 Post by **Leon** » Fri Jul 23, 2004 12:22 am

yes, they did.... the Specs are on their website (when you click on the item), and they were delivered exactly as such. I keep one everywhere, one on each floor of my house, one in my car, one at work, and one in my travel case! Keeps my battery in great shape! I'm using one of the ebay ones as I type this. If you buy more than one, they give you a break on shipping. They are really nice people. If you send them comments, tell them Leon says "hello"!

w0qj · #5 Post by **w0qj** » Fri Jul 23, 2004 12:55 am

I've been using for a year (ie: about 26 weekends= 52 days):

a IBM Thinkpad 560's AC Adapter supplying power to T40.

no apparent problem or instability, and no need to carry extra power brick to/back from work!

the maximum Amperage of the Thinkpad 560's AC Adapter is *slightly* lower than asked for by the T40 (look on the underside of the Thinkpad), but no apparent problem, even when using built-in CD-ROM, etc.

Hope this helps!

edelrc · #6 Post by **edelrc** » Fri Jul 23, 2004 1:37 am

As a rule of thumb, a 15% difference on electronic parameters is usually acceptable in electronic components. If voltage and amps are with 15% of the machines, (and the adapter is stable in those figures), you will be OK.

However, I wouln't push it any further. It may work, actually even margings of 20-25% will work too, but the device will be exponentially much more suceptible to some external componets such as, temperature, humidity, etc that will likelly trigger some component to fail.

Belive me, for $20, it is not worth it!

Kenn · #7 Post by **Kenn** » Fri Jul 23, 2004 2:27 am

edelrc wrote:As a rule of thumb, a 15% difference on electronic parameters is usually acceptable in electronic components. If voltage and amps are with 15% of the machines, (and the adapter is stable in those figures), you will be OK.

Thanks Edelrc!

I can see the 15% rule (tolerances have to be made for the variations in AC power that come through the line), but I wonder how acceptable that rule of thumb is for the batteries? I would think that the chances of ruining the charge cycle is much greater than blowing out the circuitry in the computer.

Skywing · #8 Post by **Skywing** » Fri Jul 23, 2004 8:23 am

im using one of the "Dogbone" AC adapters on my T42 at home, hasnt caused any problems, works just as it should

Leon · #9 Post by **Leon** » Fri Jul 23, 2004 9:37 am

SOME of the "Dogbone" chargers DO have the correct (4.5A) specs.. I have spoken several times to IBM Technicians, and they ALL have advised NOT to use the old ones. While machines will likely work within the tolerance, the battery and circuitry may have long term effects. I agree with edelrc, for $20, it's nor worth the chance.

edelrc · #10 Post by **edelrc** » Fri Jul 23, 2004 10:01 am

Hum... I don't know the circuitry design in TP and how battery charge is designed within that circuitry. But I think a battery problem is the lesser of the problem you could have. Moreover, theorically, batteries should be more tolerant than mnay other components in your ThinkPad. Variations in Amps and Voltage is what I see as more harmful for batteries.

Get a new adapter!. I am sure you can marry many girls out there, but how long the marriage would last is only to deteminate.

Ideas to get $20 for adapter:
-Don't go to a restaurant one day, a treat you with something special at home for it.
-Drive without AC for a couple of days.
-Rend a DVD instead of going to the theatre.
-Invite someone for icecream, and hopefully, they will invite you in return for the movies.
-Look in the pockets of that pants that you never wear now
-...

jsmit86 · #11 Post by **jsmit86** » Fri Jul 23, 2004 10:03 am

How about universal adapters?
(Targus/IGO/Kensington)

I have a Targus that works as long as the PC is on when it is connected, but will not run my T42 from a dead state.

I posted a thread at http://forum.thinkpads.com/viewtopic.ph ... ght=targus

Anyone with any experience with these?

Leon · #12 Post by **Leon** » Fri Jul 23, 2004 10:30 am

as a EE, again, I would advise against it.. the micro circuits in todays laptops can be excruciatingly sensitive to correct power... don't forget, when you battery is fully charged, your lappy is getting it's power directly from the AC adapter with no battery buffer in between... the symptom that you have already provided indicates that the lappy is not totally happy.... (hey, I'm a poet!)

Kenn · #13 Post by **Kenn** » Fri Jul 23, 2004 12:17 pm

OK, from a different tack, did those who buy AC adapters from that ebay store get the correct 4.5A ones?

cjsuh · #14 Post by **cjsuh** » Fri Jul 23, 2004 1:17 pm

I just received my AC Adapter from the ebay site. Here are its vitals:

FRU P/N: 02K6756
INPUT: 100-240V~ 1.6A-0.8A
50/60Hz
OUTPUT: 16V --- 4.5A

I noticed this is a tiny bit different from the vitals of the T42 AC Adapter referred to in the first post (Input: 1.6A vs. 1.9A):

"Input 100-240v, 1.9A, 50-60Hz
Output 16V, 4.5A"

Is the one I got compatible?

Leon · #15 Post by **Leon** » Fri Jul 23, 2004 1:38 pm

yes, input variance like that makes no difference (input is what it is).. they are 100% compatible

furball4 · #16 Post by **furball4** » Fri Mar 04, 2005 5:26 am

I'm trying to locate a cheap adapter for a 560E, and I started with trying to find out which adapters would be compatible with it. In the process I discovered that my T20 only asks for 3.36A (on the bottom of the laptop itself) but it came with an adapter that is rated at 4.5A.

My guess is that this is fine - that a higher amperage rating is no problem because the equipment will draw only what it needs. However I am electronically challenged so I would appreciate some confirmation on that. If so, I will buy a 4.5A adapter for the 560E simply because it is more likely to be useful to me in the future, for example with a T40-series.

Other than 16V, 3.36A (or higher) output, is there anything I need to be checking to ensure electronic compatibility?

Leon · #17 Post by **Leon** » Fri Mar 04, 2005 10:13 am

Both IBM and most members opinions recommend against using the higher Amp. adapter if the machine does not call for it. However, it WILL work, and if the 560E is not one that you particularly care about, you can probably "slide" with it.

Welcome to our Forums. Please add location and other pertinent information to your profile. Not required, but appreciated.

#18 Post by **jdhurst** » Fri Mar 04, 2005 10:38 am

I have read the same thing, but I am of a slightly different viewpoint. You cannot "push" current into a device - a device draws current. So if your machine wants 56 watts out of a 72 watt adapter, that is all it will take. This is also why I recommend against using 56 watt adapters where the machine is rated for 72 watts ("T"'s for example). The machine want 72 watts and will try to take it from a 56 watt adapter and overload it in the process. ... JD Hurst

bapatterson · #19 Post by **bapatterson** » Fri Mar 04, 2005 2:57 pm

Very interesting thread.

I have a T42p and had a T40 before that. At home and at the office, I use a power brick designed for the computer (4.5 amp). When I travel, however, I use my old X21 power brick, which only puts out 3.5 amps. I like to use it when I travel as it is a bit smaller than the T40 series adapter.

I have never had a problem, but it looks like I should stop doing that.

Compatibility of older Thinkpad AC adapters with T42?

Compatibility of older Thinkpad AC adapters with T42?

ow about universal adapters

Higher amperages okay?

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