Question about car chargers

[Ken]

I have a few various car chargers that accept USB cables, attaching to
various devices with a mini-USB connector. Each has its own output,
from 500 mA to 1000 mAmps. I just purchased a new device (Callaway uPro
GPS). Its car charger has an output of 500 mA.

Can I use one of the units with higher or lower output to charge the
battery? Is the highest charge rate determined by the battery or the
charger? It is a PITA to always try to find the original charger
amongst all of the gear I carry. I would prefer some options!

Thanks
Ken K
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[Ken]

Robert Baer said the following on 7/31/2009 8:57 PM:

Real automobile batteries need to have a charger that can deliver 10
amps or more; trying to use a USB port or equivalent for that function
is not a bright thing to do...

Thanks for the reply but I must not have been clear in my post. My
question revolves around small electronic equipment (bluettoth speakers,
camera batteries, GPS batteries, etc.) that can be charged in a car. I
have a collection of 5-6 of these varying in output from 250 mA to
1000mA and the question is whether I can use a charger of higher output
to charge one of lower output (is there a maximum built into most
devices to use just what is needed) or is that a dangerous process?

Thanks
Ken K

 

[Resqueline]

I believe you can use an as powerful USB supply as you like, the (consuming) device only uses as much as it's designed to. The USB setup is supposed to keep a regulated 5V output at all times so the current limiting has to be in the "receiving" device.

 

[Ken]

Robert Baer said the following on 8/2/2009 4:13 PM:

The major problems to consider are (1) is the connector compatible
physically and electrically, and (2) is the voltage output of the (car
plugin) adapter compatible with the device to be powered (eg: a 6V
device but a 9V regulated output adapter).
As long as the adapter can handle at least the load rating of the
device, the above applies; if the device is specified to draw (say)
100mA, an adapter that can supply only 10mA cannot power the device and
may be damaged if used in those conditions. However, if the adapter can
supply (up to) 10 amps, then all is OK; the device will only draw 100mA
and the adapter will run as if there was no load.

I think I am OK, then. The latest device is a GPS which has a draw for
recharging the battery of 500 mA. I have 750 and 1000 mA adapters which
match the voltage, so what you are saying is that the device which
needs 500 mA for recharging will only draw 500 mA of either the 750 or
1000 mA chargers, as I read what you say.

Thanks for your input (no pun intended)
Ken K