Matching chargers with devices, milliamps rating

SiD the Turtle · 12 Jul 2010 at 15:54

What are the rules when it comes to mixing chargers and devices, when it comes to the number of milliamps they can put out?

I would have thought say a device normally has a 1000mA charger and you plug in a 500mA one, it would take twice as long to charge. What would happen though if you put the 1000mA charger in the device that normally accepts the 500mA one?

Sp00n · 12 Jul 2010 at 15:56

bang.

Energize · 12 Jul 2010 at 16:21

Nothing because the current is determined by the voltage and resistance, I = V/R. The rated current is simply the maximum it can provide.

alex24 · 12 Jul 2010 at 16:22

I always thought that in the first instance, it might overload the charger, and in the second it'd be fine. Never tried it though.

mattyrigby00 · 12 Jul 2010 at 16:40

First case: Might work, might not
Second case: perfectly fine.

benftl · 12 Jul 2010 at 16:42

alexhull24 said:
I always thought that in the first instance, it might overload the charger, and in the second it'd be fine.

This tbh.

Aod · 12 Jul 2010 at 16:43

mattyrigby00 said:
First case: Might work, might not
Second case: perfectly fine.

nope. first case: charge half as fast.
second case: charge twice as fast, possibly damaging the battery.

Amp34 · 12 Jul 2010 at 16:44

Yup, amps is fine to have above, watts I think the same. Voltage needs to be correct though or else yes the potential for "bang".

benftl · 12 Jul 2010 at 18:03

Aod said:
nope. first case: charge half as fast.
second case: charge twice as fast, possibly damaging the battery.

You're wrong. So long as the voltage is correct, than a higher amperage rating is fine as the device will use only what it requires (I = V/R). A transformer that is underrated on the current side will most likely run hot and almost certainly not supply sufficient voltage for the device to run properly.

Nomisf · 12 Jul 2010 at 18:09

500 mA Device / 1000 mA Charger Supply - Fine, no trouble or overheating or any of that, as long as the voltage is correct.

1000 mA Device / 500 mA Charger - It may work, but the device could overdraw the charger and either cause it to shutdown, or overheat. This depends how much the device actually draws typically , as opposed to its maximum.

Its original charger may be 1000 mA , but the device may only draw 800 mA typically at full load - and anywhere below this when its "just" charging or idling - so the second option could work fine - or could overheat and catch fire. Unless you can measure it/calculate it, always best to use the correct rated charger

D.Roberts · 12 Jul 2010 at 18:11

correct first one will tr to draw to much power and could cause a fire etc.

Second as said probably fine.