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kid_couteau:
Ok kids classtime  ;D

I think one of the issues here is, and I do not mean this offensively, you do not understand how the math behind this works.

Please allow me to help.

Most batteries are termed in volts and amps or amp hours to be specific.

Most devices are in watts of power per hour of use.

Thus if you have a device that draws 50 watts of power and you have a 12 volt battery with 20 AH [amp hours] to see how long it will run "roughly" use this formula.

W=watts
E=volts
I=amps

W/E=I

So in our example

50/12=4.1666 amp use per hour so a battery with 20 AH will run the device for about 4 hours give or take.
This is a simplified view as you have to take into consideration the battery type amd amount of discharge it can handle per cycle.

Hope this helps...and I hope I didnt miss anything, not much coffee yet


kid_couteau:
Also many companies that make these banks try to deceive us by saying,"Our bank hods 12,000 mAH of power.

It takes 1000 mAmps to make 1 Amp

So in reality this 12,000 mA power bank is a 12 Amp battery.

Carl:

--- Quote from: kid_couteau on September 14, 2017, 07:19:15 AM ---Also many companies that make these banks try to deceive us by saying,"Our bank hods 12,000 mAH of power.

It takes 1000 mAmps to make 1 Amp

So in reality this 12,000 mA power bank is a 12 Amp battery.

--- End quote ---

Yep and that's not even the metric system. Many give you the battery capacity at the battery voltage,like 3.9 volts,and then tell you the inverter increased voltage to add to the confusion.

Carl:

--- Quote from: kid_couteau on September 14, 2017, 07:16:47 AM ---Ok kids classtime  ;D

I think one of the issues here is, and I do not mean this offensively, you do not understand how the math behind this works.

Please allow me to help.

Most batteries are termed in volts and amps or amp hours to be specific.

Most devices are in watts of power per hour of use.

Thus if you have a device that draws 50 watts of power and you have a 12 volt battery with 20 AH [amp hours] to see how long it will run "roughly" use this formula.

W=watts
E=volts
I=amps

W/E=I

So in our example

50/12=4.1666 amp use per hour so a battery with 20 AH will run the device for about 4 hours give or take.
This is a simplified view as you have to take into consideration the battery type amd amount of discharge it can handle per cycle.

Hope this helps...and I hope I didnt miss anything, not much coffee yet

--- End quote ---

You did miss the fact that a battery can,in good health,be used to only 50 to 80 percent of it's rated capacity safely and the high percentage of discharge will cause faster shortening of the overall life of the battery and FAST CHARGING (above 1/10 of the amp hour capacity) will also damage the cell chemistry.

  That is why my math might look strange,I use real world usage rather than actual unicorn math of the sales pitch .

I re-reading I see you did include the rate of discharge,but I put in within my estimate so as to simplify the message.

surfivor:

How does that anker 400 3.9 volt battery compare as far as output to a regular 12 volt battery such as a car battery or a typical RV deep cycle battery ?

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