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Replicating 2 dcell batteries with a power adapter 
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#1
Nov2810, 08:51 AM

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im new to finding this site and sorry for the lame question.. im just a tinkerer and in need of some info..im working on a project that uses 2 dcell batteries in series as a power source. so i thought id get a power adapter to save on buying batteries sounds easy ? hardley for me, 2x dcell batteries = 3.0 volts no problem, but amps is my question.. i found on another site that d batteries have 13000 m/a (i think i typed that right) so if u have 2 in series does that give u 26000 m/a ? if so i would need a power supply with 3v and 26.0amps. any of the above is subject to be wrong.. if anyone could help me make it right it would be much appreciated..ty bill



#2
Nov2810, 09:42 AM

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You might have read 13000 mAhours or 13 Amphours.
A 13 Amphour rating says that the product of current and time the current is flowing for this battery is 13 amphours. It may not be able to actually supply 13 amps at all, but it might produce 1.3 amps for 10 hours, for example. The product is 13 amphours. It doesn't tell you anything about the current that can be supplied. 13 amphours for a D cell sounds very high. Maybe 4 would be more like it, but that's just a guess. Assume it is 4 amphours. If you put two in series, the combination would still be 4 amphours, but at 3 volts. All of this is useless if you are going to put a power supply in instead of the batteries. A power supply has infinite (or indefinite) amphours because it works as long as you plug it in. A D cell might be able to supply 3 amps reliably and maybe 8 amps for a short burst. But you need to check on the load, not the battery. What current does it draw at 3 volts? That is the current you need to supply. 


#3
Nov2810, 09:46 AM

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#4
Nov2910, 06:22 PM

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Replicating 2 dcell batteries with a power adapter
well answers were kinda helpfull, let me tell u what im doing it might help. im copper plating my cast lead bullets with a solution of copper sulfate, it workes really well so far but i cant afford to keep buying d batteries.. so i guess i need to figure out how many amps its taking to do the work then buy an adapter thats rated at least that high or higher ? thanks for responses and sorry for the electrical ignorance on my part.



#5
Nov2910, 06:44 PM

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As stated, batteries are rated in their energy storage capability, which is Amp*hrs (* voltage). To keep it "simple", the units used are Amp*hrs (even though the units of energy are Joules in the main metric system used). Anyway, to figure out what current the batteries are running at, you would take the Amp*hr rating, and divide by the number of hours the setup can run before discharging. That gives you a ballpark estimate of the current that it is running at for that time. The voltages of the two batteries add in series, which is why you get about 3.3 to 3.0V with fresh alkaline D cells. The current is the same in both batteries since they are in series  you are just getting twice the energy by virtue of twice the voltage (Power=V*I, Energy = Power * time). It looks like 12,000mA*hr (or 12 Amp*hours) is a typical Dcell alkaline capacity: http://en.wikipedia.org/wiki/List_of_battery_sizes So if your plating works for 2 hours on the D cells, then your setup is probably running at about half of 12 Amps, or 6 Amps. If it runs for 12 hours of plating, then your current is likely around 1 Amp. Makes sense? 


#6
Nov2910, 07:01 PM

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I have tried a bit of electroplating and always got better results with a small current for a longer time.
For something like a bullet, probably only 50 mA would be enough current. Otherwise you can get a mess of black Copper gunk which does not stick properly. You could get 50 mA from almost any small power supply. From 12 volts DC you could put a 220 ohm resistor in series with the electroplating cell. It would still only take 15 minutes or so to get a coating. I hope these are not live bullets you are passing electric current through? Are they? Why are you copper plating bullets? 


#7
Nov2910, 07:19 PM

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#8
Nov3010, 07:49 PM

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