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What is the meaning of mAh difference for same model battery?

This is a discussion on What is the meaning of mAh difference for same model battery? within the RAM and Power Supply Support forums, part of the Tech Support Forum category. I have an 8 year old Asus 73S computer and its battery is like this: Model: A32-K72 10.8V 5200mAh 56Wh


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Old 02-26-2019, 12:34 AM   #1
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I have an 8 year old Asus 73S computer and its battery is like this:



Model: A32-K72 10.8V 5200mAh 56Wh



I saw a battery on internet, as follows



Model: Same as above. 10.8V 4400mAh 48Wh



Although same model it has lower mAh and Wh as you see.



What difference does it make, when mAh and Wh is different? It will not harm my computer right?

And of course this is not from original manufacturer and they only give 6 months warranty, and after that what is your opinion? Big difference in price between original and not original.
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Old 02-26-2019, 01:14 AM   #2
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No, a lower mAh or Wh won't harm your computer. They are simply measures of how much electric power the battery is capable of providing over time. In short, those numbers indicate the capacity of the battery. A higher value means more charge stored by the battery which in turn means a longer lasting period of battery power use.

Do not expect the same (original) quality and reliability from third-party batteries. The warranty period alone should give you a hint of what to expect from the battery. You get what you pay for. If you find the offers on third-party batteries irresistible and opt to buy them instead, don't expect them to last as long as the original ones do.
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Old 02-27-2019, 07:05 AM   #3
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Lower mAh (milliamp hour) rating should not "harm" you computer, but it is usually best to use a battery of at least the same current rating.

If your notebook needs 52W to run and the maximum this smaller replacement battery can provide is 48W, at best, you will have a shorter run time. But if the currant rating is too low, the notebook will not even start, or will be unstable and shut down unexpectedly - and that could result in corrupt data.

Note that watts = Volts x amps. Your notebook needs a certain amount of watts just to run. Since your voltage is the same, and your current rating is lower, that clearly means fewer watts will be available to the motherboard, CPU, graphics, drive, and monitor screen.

I do NOT recommend you buy that battery.

It would be like putting a 12V battery made for a little 4 cylinder Toyota into your big V8 Ford truck. Yeah, the 12V is right but that does not mean the battery has enough current behind it to turn that big engine over to get it started. This would be especially true if that battery (car or notebook) is cold - like first thing in the morning.

You can, however, buy a more powerful battery AS LONG AS the voltage is the same and, of course, so are the connectors. The notebook will only pull from the battery the amount of power it needs, so having a battery with a higher current won't harm anything either, but will give you a longer run time - a good thing! And while the battery may try to suck up more during a charge, the regulator circuits in the charging circuit "should" prevent an over current situation.
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Old 02-28-2019, 11:15 PM   #4
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okay thanks for the answers. i bought the battery, it arrived and i am using it since yesterday, so far no problems but of course its running time is less than the original battery when the original battery was new, which is not a big deal for me as i use it like a desktop almost always.

now here is another question about this. i looked at the user manual of battery and it says the following, but they may be generic wording so please comment:

-charge the battery for 8 hours when computer is off before using it first time. this will enable the cells of the battery to open

-minimum 2-3 times a week, consume the battery until the the computer brings itself to sleep mode

-if the computer will be plugged more than 3 hours, remove the battery from its slot after it is charged 100%. Long time plugged in usage causes heating and harms cells inside the battery

-Li-ion batteries can be charged 400-500 times at full capacity. After this, their performance drop

Please comment on these - do they make sense? especially the 3 hour item
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Old 03-01-2019, 02:41 AM   #5
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Quote:
Originally Posted by ketanco View Post
okay thanks for the answers. i bought the battery, it arrived and i am using it since yesterday, so far no problems but of course its running time is less than the original battery when the original battery was new, which is not a big deal for me as i use it like a desktop almost always.
Don't expect it to last as long as the original did either. You made your choice and so be aware of the implications. Better hope that the warranty facilitation is a smooth process and hope even harder that you never get to needing it. If it lasts longer than the warranty, brace for failure at any time thereafter. Don't let me scare you though, I'm just giving you a heads-up.

Quote:
now here is another question about this. i looked at the user manual of battery and it says the following, but they may be generic wording so please comment:

-charge the battery for 8 hours when computer is off before using it first time. this will enable the cells of the battery to open
8 hours is extremely long to me especially for a battery of its capacity. While batteries are usually not charged to full at the factory, they are often charged to some level to make sure the cells are taking and keeping a charge as expected. This charge depletes slowly as the battery sits on shelfs awaiting purchase or in storage, so it's recommended that you charge them to 100% and leave it plugged in for an extra 3 hours.

This doesn't "open" the cells as stated in the manual, but calibrates the battery to make sure the operating system is doing the correct estimations of the battery's full charge capacity and calculates/displays the correct battery percentage levels as the battery's charge rises and falls accordingly.

Leaving it plugged in for 8 hours doesn't make a difference IF the battery has been built to the required standard because the "smart" battery has a management system inside it that controls when the cells are charging and when they are not. This system is responsible for protecting the cells against overcharging, undercharging, overheating and defects that may occur, thus preventing damage to the laptop, fire, explosion and injury. In short, the battery management system (BMS) is a necessary and standard safety feature of a rechargeable battery pack. Whether this particular battery meets the required quality standards is in question, so I can only recommend using the battery as per the manual that came with it. The manufacturer of the battery knows better than any of us why that should be the case.

Quote:
-minimum 2-3 times a week, consume the battery until the the computer brings itself to sleep mode
I believe the manual means using the battery until it's charge drops to the lowest permissible level (critical level) which usually triggers the computer to shut down and prevent further draining of the battery. This keeps the cells in prime condition and prevents premature failure of the cells because keeping the cells fully charged for long periods can damage them. The same also applies to keeping the cells discharged for long period, so to keep the cells healthy, this periodic discharging and recharging is recommended. For quality batteries, this is only recommended at least once a month. However, since we do not know how good the quality of the cells is, we have no choice but to again follow the manual.

Quote:
-if the computer will be plugged more than 3 hours, remove the battery from its slot after it is charged 100%. Long time plugged in usage causes heating and harms cells inside the battery
As stated above, the battery management system is supposed to take care of this, but that is the case of batteries that are built to standard. We have no idea if this particular pack is built to the required standard, so we cannot say for sure if this is necessary. Therefore, the manual, again, takes precedence.

Quote:
-Li-ion batteries can be charged 400-500 times at full capacity. After this, their performance drop

Please comment on these - do they make sense? especially the 3 hour item
That much is true. The number of charge cycles will vary with the quality of course, but the cycles are finite.
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Old 03-01-2019, 03:10 AM   #6
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Stance, you have the patience of a saint to type this stuff ^^ up :)
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Old 03-01-2019, 07:58 AM   #7
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Quote:
Originally Posted by ketanco
-charge the battery for 8 hours when computer is off before using it first time. this will enable the cells of the battery to open
Quote:
Originally Posted by Stancestans
This doesn't "open" the cells as stated in the manual
Right! That "open" comment makes no sense. Perhaps something was lost in translation. It is true as batteries get closer and closer to fully charged, the charge rate (flow of current) decreases and decreases which may give the appearance the circuit (but not cells!) opened. Kinda in the same way the passing of time slows down the closer you get to the speed of light!

Anyway, I am glad your new battery works.

BTW, many battery instructions say you should never leave the charger plugged in for long periods of time. I am convinced that is just shyster... err... lawyer talk in the event there is some major fault due to a manufacturing defect.

Years ago, in particular with NiCad batteries, there was a serious problem with " memory effect". While memory effect does affect Li-Ion batteries too, it is to a much lessor degree and is much more easily mitigated.

The point to remember is notebook charging circuits will prevent your battery from over charging. And they will also stop charging when the charge reaches a specified point, and will not begin charging again until some lower threshold is crossed.

While one anecdotal example does not set the rule, I will say that my 9 year old Toshiba notebook, with its original battery, stays plugged into the charger 24/7 for weeks at a time. If you look at the specs .pdf, you will see the rated battery run time was 2 hours and 35 minutes - I know, that is lousy by today's standards but not bad back then with a large 16" display. Anyway, today, I get just under 2 hours which IMO, is pretty good for a 9 year old battery. So clearly, leaving it plugged in did not hurt it.

I do about once a month, unplug it and run the notebook until it automatically shuts down. Then I plug it back in for another month.
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Old 03-01-2019, 11:55 AM   #8
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thanks for the replies. my old original battery (8 year old) lost its capacity about 3 years ago i think it was because of i never did the unplugging thing, and left it plugged for months sometimes. i guess, at a minimum like you said, i should have drained it once a month. then it means you are not doing the battery removing thing if it will stay plugged in for more than 3 hours.

as for performance report with my new battery, i got a little over 2 hours of run time, with normal usage, and my screen is 17".

BUT one negative thing was, it seemed to drain normally down to about %15, then suddenly went to about %7 and then it put itself to sleep ... i had to plug it in to turn it on again, which it turned on normally (not like from irregular shut down ) i was waiting it would drop to %1... it didn't happen
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Old 03-01-2019, 12:19 PM   #9
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Quote:
thanks for the replies. my old original battery (8 year old) lost its capacity about 3 years ago i think it was because of i never did the unplugging thing, and left it plugged for months sometimes.
I think if you dig around you will see most notebook batteries need replacing every 4 - 6 years so yours seems to have hit the average spot on. I don't believe leaving it plugged in had anything to do with it.

Quote:
BUT one negative thing was, it seemed to drain normally down to about %15, then suddenly went to about %7 and then it put itself to sleep ... i had to plug it in to turn it on again, which it turned on normally (not like from irregular shut down ) i was waiting it would drop to %1... it didn't happen
This likely goes back to Stancestans comments about calibrating the battery. Actually, it is not calibrating the battery, but calibrating the notebook's battery monitoring feature to the battery. So running the battery all the way down, then charging it all the way back every few weeks helps ensure the notebook's battery monitoring feature is properly calibrated to the battery for a more accurate "estimate" of the remaining time.

I emphasize "estimate" because that is all it can be. Computers never put a constant load on the power source. It is always varying from next to nothing when idle to a full load when taxed with demanding tasks to something in the middle, then back and forth again. So at best, it is always a guess.
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