Help Safe to charge DX using any mini-usb charge source? (worried about current ratings)

[trale]

This has been an issue that's been bugging me the last few days now. The stock wall charger that came with my Droid X is the 5PN5504A, which has an output rating of 5.1V, 850mA.

My understanding is that the mini-USB interface is an industry standard for power delivery to portable devices, which I take to mean that any charge source should work (wall charger, desktop PC, laptop) as long it has uses an USB interface. So any USB-->miniUSB cable can be used to charge any mini-usb device, regardless of power source, right?

I already have several other mini-usb devices, such as bluetooth headsets, which all came with their own wall chargers. However, I checked these chargers, and they all have different outputs: 5V @ 200mA, 5V @ 150mA, 5V @ 550mA.

Because the default Droid X cable was so short, I was tempted to use these other chargers. I plugged in the 5V@150mA charger to my Droid X, and found that the phone does not show it's charging (the lighting bolt isn't there, there's no animation on the battery indicator). So then I switched to the 5V@550mA charger, and it DOES charge.

I guess this means is that certain devices have a minimum charge current at which they will charge. So my worry is, is there a MAX charge current as well? I understand that using a higher current will charge the battery faster, but if I use a charge source the provides more than this safe max amount, will it fry the battery or shorten it's lifespan?

I recall from prior research that each USB port in a PCs provide 500mA, but how do I interpret this?
- Does the port provide constant 500mA to the connected device?
- Does the port provide a maximum 500mA to the device, but varies depending on how much the the device needs
- Is there any harm if I charge my bluetooth headsets using the PC USB port? (the one that comes with 5V @ 150mA charger)
- Do smaller laptops (netbooks) USB ports deliver less current than PC USB ports?

Any advice or illumination would be highly appreciated, whether specific to the Droid X or mini-usb devices in general.

 

[kg2128]

I've searched this on google as well, and in theory as long as the voltage and amperage is lower than the specs on the droid x charger it should be safe. If the specs are lower it should charge slower, if they are a lot lower there is even less risk but as you saw it might not charge at all. I have also seen threads where people insist that you should not use a different brand because their droid was damaged or became less responsive or something like that. The only problem with the "damage" threads is the OPs were never rational, they were usually angry and stubborn, so if it was something else they would not admit it.

 

[kwaping]

How about changing the usb cable that came with the DX charger for a longer one?

FYI for all the former LG Dare owners out there, the Dare charger is 5.1V 700mA and charges the DX just fine.

 

[trale]

How about changing the usb cable that came with the DX charger for a longer one?

I just ordered one, but having multiple options for charging this phone would be convenient (home, work, travel, etc).

 

[crackaonrice]

Have you tested whether it is ACTUALLY charging or not at 150mA? Because I am having the same issue right now...where I have a source that is 5V, 400mA...and the lightning bolt doesn't show up and the phone doesn't indicate charging. I guess the threshold for the phone to go into charging mode might be like 500mA or something?

 

[colchiro]

Your computer will charge at about 500mA (as was stated), however your stock charger is rated at 5.1v 850 mA. I needed a magnifying glass and a good light to read it.

It's possible to make a cable that uses current from two computer usb ports to charge at up to 1 amp, but I've never seen one on the market. Two of the wires need to be shorted to make it a charging cable, instead of a data cable.

 

[Riverman]

A charger with a higher amperage rating than stock is also safe to use. The phone will only draw what it needs. In some ways it's like your house. a typical outlet is connected to a 15 amp circuit, but whatever you plug in only draws the amount of power that it needs. You're actually more likely to run into problems if the power supply can't provide as much power as the connected device is asking for. For the record, I use a 1.2 amp Nokia micro USB charger and it works perfectly.

 

[old.blue]

A charger with a higher amperage rating than stock is also safe to use. The phone will only draw what it needs.

Absolutely correct. I have a multiple chargers I use to power my DX; a 1 amp charger I use in the car, the stock .85 amp charger the phone came with, and a .5 amp charger at home. They all work fine, but obviously the higher amp charger charges the battery faster. I've even used the one for my iPod, and it works just as well.