Posted on 08/23/2018 12:06:02 PM PDT by Rebelbase
Question for FReepers gifted in electrical knowledge.
When matching wall plugs and batteries to devices with a, say 850 milli amp requirement which is safer if the exact milli amp plug or battery is not available.
Is it OK to use a lower milli amp or should a higher milli amp be used.
I am under the impression that using the wrong one can cause damage to the device.
Just make sure the source is at least as much as is required. If the device needs 850 miliamps, and you’ve got a 5 amp source, you’re good to go, assuming the voltage is the same.
Match voltage, AC or DC, plug size and polarity (usually middle is positive). Use the higher milliamp rating, 1 amp equals 1000 milliamps.
The Ampere rating is how much current the device can DELIVER to YOUR device.
Too little and it might not work properly under full loads.
The higher number would not be a problem unless there is a short circuit and more current than the device needs is being dumped into your device.
Your device will draw only as much as it needs unless it’s defective.
Say your device needs 500 milliamps to run properly. Your power supply can deliver 800 milliamps. You’re okay.............
Oh, and make sure the VOLTAGE is the same!...........
To be clear, if you have an 850 milliamp (it’s really .85 amps) device, I’d get at least a .85 amp charger. Nowadays, most of them are at least 1.0 amp though. But you may want to google this. The devil is in the details. Nowadays, with most of this being a case of using the plug to charge the internal battery, rather than use the device, you may actually be able to use a lower amperage source. The stuff is pretty “smart” these days so it may not do any damage - but be slow to charge.
My water heater went out last year and I thought it would be a great opportunity to go tankless. But I looked into it and tankless use a LOT of amperage since they are heating the water as you use it.
My water heater was on a 30 amp circuit, but the tankless ones I looked at all needed 60 amps. So I got another water heater. :(
Voltages must match and source current must be larger!
Gas is the only way to go for a tankless water heater.
Think of it this way. Your device will be “Sucking” the juice from the wall. the comparison between the 850 ma and a 1700 ma charger is like sucking from a 1 gallon bucket or a 2 gallon bucket. So long as the supply (sucking amount) is at least as large or larger than your device requires, you are good to go. (Assuming the voltage is correct)
Thank-you all!
One last question, The milli amps would be considered the source current?
Agreed. Make sure that the voltage is the same. And if it is DC or AC output.
You should be able to find the load requirements on the gizmo back plate.
Then any AC converter/adapter that has a current rating of the device rating or higher should be okay.
I did this with an old router the — AC adapter died and I found one that worked in a bonepile. I had to replace the end but it worked and still works.
Important: there are special requirements for battery chargers. If you use an incompatible charger/AC adapter, the battery might thermally runaway while charging and catch on fire. There is protection circuitry to prevent this from happening in a compatible charger/AC adapter. For that use the manufacturers recommendation.
Milliamps is 1/1000th of an amp. Therefore the milliamp (ma) is the amount of flow. If it was water it would be gallons instead of ma. Ma could be either amount required or supplied just like gallons.
Cell comes with a wall charger...sorks OK
Purchase a low cost car lighter socket (12v input) charger and it doesn't hold charge when driving and using the cell phone
Need a "fast charger" can deliver up to 2Amps or more and is more expensive.
PS.....look for dual output car chargers...some have 1A and 2.5A outlets.
I live in the sticks. I don’t have gas except for [insert joke here]. :)
Source for the gizmo that you are powering. Load current for the wall outlet that your AC adapter plugs into.
There is usually conversion inefficiencies, approx. 30% loss, and so the effective “load current” at the wall outlet will be higher.
There is also a conversion step — AC to DC — which is done through rectification and a capacitor. AC means negative voltage swings in addition to positive. DC is positive + for the gizmos that you are powering/charging/using.
Although negative voltage can be generated too.
It would be the “source current” once the device is plugged in and working.
It strikes me as kind of a funny term, because since current cannot disappear (well, I guess it can if you have a short circuit or crappy wires that allow for a lot of leakage) if there IS current then source current will be the same as “device” current or “draw” current or the best term would be “load” current.
I suppose, theoretically if your load draws 850 mils and you have 3 mils of leakage, then your source current would be 853 mils. That would be considered a lot of leakage, by the way.
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