Power bank 14000mah

Hello all,

Am I right to assume that If my laptop battery is 6900mah and I am getting a 14000mah power bank, then this could triple the life of my laptop battery?

Thanks

 

No, you cannot make that assumption.

The only useful measure of battery capacity is Watt-hours, which combines both the amps and the voltage. You can check the voltage of your laptop battery (it should be on the label) while what is the voltage of the power bank?

There are also likely to be conversion losses as the power goes from the power bank batteries to its output and then to your laptop's input (how will this be? Using an inverter to get mains voltage?). Something else to watch out for is that if your laptop thinks it is running on mains power then the measures to reduce power consumption when running on battery won't apply.

John

 

These are the stats of the battery of my laptop: 19V 2.37A 6900mah

Can you please check the power bank here? (there's just too much to paste )

Amazon.com: Turcom Ultra Capacity Portable External Battery Pack for Laptops and Notebooks (TS-282): Computers & Accessories

Thanks!

 

ah yeah, that's a bigger one. But I just wanna understand the concept..

 

Thank you for the extra information.

The 19V 2.37A is the PSU rating (45W). You need to either examine the battery label or run a program such as BatteryInfoView to see the battery voltage (the program will also give you the capacity, which is what matters (1 Whr = 1,000 mWHr).

Buried in the description for the external battery is "Capacity: 33600mAh Size: 214.513021 mms Input: 15V / 24V Output: 15V/20V - 125Wh". A quick calculation of 125 /33.6 gives 3.72V which is plausible (the nominal voltage of Lithium cells is 3.6V).

The usable capacity will be less than 125Whr, perhaps 100Whr. Note that the battery you linked to has more capacity than the 14000 mAh you mentioned in your first post. If the same voltage applies then 14000 mAh means 52 Whr gross or (my best guess) about 40 Whr usable capacity and because your computer thinks it is on mains power the extra run time is likely to be reduced.

I presume that you are looking at this alternative because your computer has an internal battery that is not easy to swap.

John

 

Here are some stats:

Battery Name AP13F3N
Manufacture Name SANYO
Full Charged Capacity 43,965 mWh
Designed Capacity 47,100 mWh
Battery Wear Level 93.30%
Voltage 7,935 millivolts
Chemistry Lithium Ion
Low Battery Capacity (1) 2,393 mWh
Low Battery Capacity (2) 3,045 mWh

 

Yes, it's an ultrabook. I cannot swap it on the go

 

Now that you have the stats will you be able to tell me the how many Whr mine has?

As I understand, this way we will be able to calculate the difference between my battery and the power bank and answer my initial question

Thanks for the help!

 

Your current battery is rated at 131 WH's (19Vx6900mAH/1000).

If the power bank could convert perfectly (lossless) it's potential to power your system (it can't);

Then the model you're indicating is 266 WH's (19Vx14000mAH/1000).

This will give you roughly two times the capacity of your current battery for an overall run time (internal battery plus power bank) of almost 3 times what you're getting now for any given/fixed workload.


Again; a lot of assumptions here, but the numbers give the best indication.


Note: as long as the power bank's mAH rating as stated is able to be delivered with the same voltage that the device requires (in your case; 19V) then you can compare mAH directly to see how much longer your device will last.

Where the variables come into play is; how does the power bank supply this power to the notebook. If directly (like a replacement battery), then it should be very close to it's rated specs. If however, it is connected to the DC plug and is charging the main battery, then we'll probably see inefficiencies of at least 15% or more.

Hope this helps.

 

Many posts before mine showed up. Hmmm...

OP, your posted battery specs are not using the correct units, but you can put in the right numbers to the calculations in my post to get a more accurate assessment of this topic for your specific question.

 

Yes, that helps, thanks!

Now regarding my capacity I am a bit confused.. the battery software gave the stats above, but if I go here and check the specs it's a compleeeeeetely different figure:

Acer Aspire S7-392 Specifications | Digital Trends

As you can see my laptop is Acer s7-392.

Let's see how we can solve this one also

 

From the info you posted above your battery is:

Full Charged Capacity 43,965 mWh = 43.965 Wh
Designed Capacity 47,100 mWh = 47.1 Wh

The battery info on the Acer specifications you linked to is incomplete because it only give the Amp-hours without the voltage. However, the design capacity of your battery divided by the 6.28 Ah in the specs gives 7.5V - plausible for 2 lithium cells wired in series.

Therefore the 14,000 mAh power bank is likely to increase the run time by about 75% (if it is 14,000 mAh 3.7V). If you want to triple the run time then you would need the 125 Whr battery that you linked to and that will be some significant extra baggage.

John

 

John, am I confused?

The power bank cannot power the notebook at 3.7V - it has to be at least as much as the notebook requires; 7.5V, correct?

It that is correct, that would make the power bank 105WH which should still triple the total run time for a given workload (roughly, of course).

 

I'll try to deconfuse you.

The specs of the power bank linked above included .... 33600mAh .... 125Wh ..... . By deduction that indicates 3.72V (V = W/A). The power bank will contain a voltage converter to get the output to the 15V - 20V to feed into the notebook which will then convert it back down to whatever voltages are needed by the components.

The info here says the DC to DC conversion efficiency is typically between 75% and 90% (quite a wide range).

John

 

Thanks John, my quick read interpreted it as 33600mAH at any voltage between 15V-20V.

 

I agree, the info was confusing and potentially misleading. I had the read it a couple of times to find the Watt-hour value.

Many notebook manufacturer's specs are no better.

John

 

It seems to have gobs of power, per the description 125Wh, more than enough. Here is the rub though, there is no charger. It uses an adapter plug for your laptops charger. if your laptop takes huge amounts of time to recharge the standard battery my guess is with this it will now take that much longer.

 

That's a valid point. The info above indicates a 45W PSU so it would most likely take >4 hours to charge the battery during which time the PSU isn't available to charge the computer. This may or may not be a concern depending on the usage pattern. I'd probably buy another 45W computer PSU since it's useful to have a spare.

John

 

Ok, all is clear.

Thanks, guys!