Phone chargers (AC Adapters in general)

Factual Questions
1

I have 2 cell phones, same brand (SonyEricsson), diff models (T637, T300). Can I use the T300’ charger in the T637? Both chargers fit inside the charging port on the phone. Reading the back of the built-in AC Adapter of the charger, I see:

T300 charger:
Standard charger CST-13

2

d’OH! :smack: How’d accidently hitting TAB+RETURN make it submit my unfinished post??

Anyway, the AC Adapter on the T300 charger says:
Standard charger CST-13
INPUT: 100-240VAC**-150mA ** 50-60 Hz
OUTPUT: 4.9V — 450mA

The AC Adapter on the T637 charger says
Standard charger CST-13
INPUT: 100-240vac ~70 mA, 50-60 HZ
OUTPUT: 4.9 VDC — 450 mA

(bolding mine to show the differences)

So will I blow up my phone if I use the chargers interchangeably? (BTW, tried searching my usual SonyE forums, no real info found).

3

Looks to me like they were designed to use the same charger. The odd thing is that two chargers with the same model number have two different current ratings. I’d be surprised if they weren’t identical inside.

However, if you only go by the rating, these are basically voltage sources, which means that they will try and keep the same voltage and will vary the current to match what the phone (or whatever you hook it to) needs. The current rating is the maximum rating. The one is rated for 150 mA and the other 70 mA. If you knew for certain how much current your phone needed then you could safely say if both were usable on both phones. Without knowing that, all you can say is that you can use the 150 mA one on either phone, but the 70 mA one only on the phone it came with.

If, for example, the phone happened to draw 100 mA, then the 150 mA one would have plenty, but you would be above the rating of the 70 mA adapter. If both phones only need 50 mA, then either phone could be used with either adapter. If you can find the current specs from the manufacturer’s web page then you might know for certain, until then keep each adapter with its respective phone.

4

I think the distinction about input amps has to do with the matching voltage. That is:

150 mA at 100
or
70 at 240

Since the chargers can handle mutliple voltages automatically, the amps drawn depends on the voltage used. (So wattage stays more or less constant.)

I suspect someone noticed a mislabelling in an earlier version and fixed it.

5

The manuals that came with the phones should have the current rating of the battery that came with the phones.

Regarding AC Dadpters in general
Aren’t they a pain. Just like rabbits, start with two and pretty soon they are all over the place. Different voltages, different current capacities, diffferent sizes, and the wires are either too short of too long.No wonder the back of a computer desk looks like a rat’s nest!
Wouldn’t it be nice to have just ONE power supply device with a power supply cord for each device/function on your computer or periphery?

6

I forgot to mention that the power supplies are never identified with what device!

7

Eh, that’s not always true. I’ve got (or at least had) quite a few that say something like “For Use With Model XYZ Widget Mark II Only” or somesuch. A great number of proprietary power supplies that are included with various pieces of equipment are similarly labeled.

8
      • I would test the first wall-adaptor with a multimeter, to make sure it is not sending AC. Assuming the labels were copied correct–note how the second one says 4.9VDC, where the first one only says 4.9V. These adaptors can send either AC or DC and they pretty much look the same externally, read them labels carefully before switching.
        , , , ,
        …I would bet that the phone that came with the “DC” adaptor very probably has enough diode protection to withstand being hooked up to an AC charger of the same voltage, but I don’t know. It just makes sense to me that people would connect the phone to the incorrect charger (of another voltage or AC) and so within reason the phone should have built-in protection against such conditions. It might beep an alarm if it is hooked to the wrong power source, especially one too high a voltage.
  • The two different current ratings are probably because the two different wallblocks (which is what them things are called) have different-capacity fuses in them. The fuses are usually non-replaceable, inside the wallblock casing, soldered inline with the outside-end of the secondary winding and tucked underneath the layer of tape wound around the transformer coil. Most cheaper wallblocks are trash if you pop the fuse, not because the fuse itself is so hard to replace–but because there’s usually no indication anywhere of what the capacity of the original fuse was.
    ~
9

One of the first things I do when I get a device with one of these adapters is to take a piece of masking tape and a Sharpie and mark the name of the device on the charger. Makes life a lot easier when trying to figure out which charger I need to plug something in to.

10

Who cares what the original value of the fusible link was? If you know enough to find the thing, you certainly know enough to choose a reasonable replacement either based on measurements of the actual load, or determined from the wall wart’s rating plate. Usually it’s just not worth the trouble, however, since the transformers are usually varnished and just getting to the fusible link is a royal pain in the ass. Even then, more often than not the transformer windings themselves have opened somewhere deep inside, due to thermal failure. Replacements are usually cheap and readily available.