# Thread: Battery Size In A Jump Starter Pack

1. ## Battery Size In A Jump Starter Pack

Can any one tell me if there is a way to know how many true amp hours are in a portable jump starter.

I know this will vary depending on its size.

I have a son coming back from USA and the unit that I want says 2000A peak 20000mAh

Now to me this is gobberlygook. To travel with it on a plane a lithium battery has to be under 100 watt.

How do I or airport authorities calculate this?

This is the unit Robot or human?

2. Originally Posted by d2dave
Can any one tell me if there is a way to know how many true amp hours are in a portable jump starter.

I know this will vary depending on its size.

I have a son coming back from USA and the unit that I want says 2000A peak 20000mAh

Now to me this is gobberlygook. To travel with it on a plane a lithium battery has to be under 100 watt.

How do I or airport authorities calculate this?

This is the unit Robot or human?
20000ma = 20A
20A x 12v = 240watts

3. Originally Posted by Vern
20000ma = 20A
20A x 12v = 240watts
Thanks Vern. I understand ohms law. What I do have trouble with is that such a small device could have a 20 ah battery.

This being the case I could run my 40 litre Engel for about 13 hours off this.

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They don't. They have a total of 20AH @ a nominal 3.7V. That gets divided by 4 to get a nominal 14.8v (peak of 16.8 but it'll put a float on the car battery sharpish). So realistically 5AH, but then that's also Chinese Amp Hours, or 5AH PMPO.

My power bank here is 26800mAH and the label says 99.16WH.

5. Why import one when they are cheap as chips here - mine off ebay was a little less than \$100.

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Originally Posted by d2dave
Can any one tell me if there is a way to know how many true amp hours are in a portable jump starter.

How do I or airport authorities calculate this?

This is the unit Robot or human?
Right there on the specifications page: Capacity: 20000mAh (73.2Wh)
So they've used a nominal voltage of 3.66V

The way to know how many "true" amp hours are in the device is to do a couple of calculated discharge tests. I have a specific rig built to do that with a controllable load, a couple of GPIB volt meters and a calibrated shunt. But that's probably a bit more than you need.

7. Originally Posted by 101RRS
Why import one when they are cheap as chips here - mine off ebay was a little less than \$100.
From my research it appears to be a really good brand and freight is free, so no much over a \$100

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Originally Posted by d2dave
From my research it appears to be a really good brand and freight is free, so no much over a \$100
Make he doh me checks he can carry in checked in luggage

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