Today's Audience Participation Moment

[c9]

If I use a 15V 2.0A AC Adapter for my laptop, which officially requires a 15V 3.0A Adapter, and it works fine for a couple years, what sort of damage may I have wrought?

(My laptop battery doesn't play properly anymore, so I suspect that I killed it. Silly me, not paying attention to these things. I totally do NOT get electricity.)

Comments

[cap-hill-latte.livejournal.com]

Laptop batteries only tend to last a few years anyway so I doubt that the power supply is the issue.

I *think* that using a lower amperage source is fine - it's using a higher source that would case problems. (If anyone out there actually paid any attention in first year engineering feel free to correct me.)

2a vs 3a

[petele.livejournal.com]

A 2a vs 3a fuse isn't going to do anything. A fuse is a limiter, if you go above a certain amount of current (amps), they blow. Thus, if you put in a lower amp fuse, and your device doesn't blow the fuse, then everything is okay. If you put in a 6amp fuse, there is possibility of damage, but puttin in a lower value won't do anything.

PEte

Re: 2a vs 3a

[c9.livejournal.com]

Oh! I thought that the 3A referred to the actual power being supplied, not a limit on the power. Hrmmm. I really should take a course that explains all this stuff, like that Physics course I slept through in first year.

Re: 2a vs 3a

[petele.livejournal.com]

think of electricty this way...

Voltage is the strength/force of the electricity.
Amperage is the amount (quantity) of electricity flowing.

Re: 2a vs 3a

[c9.livejournal.com]

Yeah, that still doesn't make any sense. I've read many textbooks that say things like 'think of it like the amount of water versus the speed of water' and all sorts of other metaphors, but they still don't really click for me. I guess I'm just electricity-challenged.

[simplisticton.livejournal.com]

I may have this totally wrong, but if so, so did the person I asked (who's an electrical engineer, but the chance is higher that I misunderstood his explanation, which went on for about the length of a coffee-break)...

When you're recharging a battery, the resistance varies with the current. When you start charging a nearly empty battery, the resistance is low and the current is high (i.e, the battery takes everything it can get). As the charge increases, the resistance increases and thus the amperage drops (so called "trickle-charging"). In your case, the power-supply was under-amped for the job of charging the battery, so the battery took longer to receive a full charge, thus causing the resistance to be higher for longer. High levels of resistance = high levels of heat = bad for battery.

So yeah, you probably did some damage to your battery, but, like Pete says, you typically don't get more than a couple of years out of a laptop battery anyway because they're damn easy to abuse.

[simplisticton.livejournal.com]

Err, Sarah, not Pete. Whoops.

[cap-hill-latte.livejournal.com]

This person wasn't Veech was it? Or Dr. "I called NB Power to ask them to turn the power down" Wasson?