Laptop battery charging

[G0AOZ]

I think I'm correct in saying that generally speaking a laptop's main battery can be charged up, whether or not the PC is actually switched on and running. But does it charge at the same rate (current) if the PC is running, or slightly less? Not a very scientific method of determining this, but I've noticed that the PSUs generally don't seem to get any hotter when the PC is running. Other than "breaking open" one of these PSUs and unsoldering an LT connection to insert an milliammeter, I'm not sure how else I could prove it.

ROGER - G0AOZ.

 

[Crowley16]

have you considered running your batter down to like 50% exactly, and then charging the thing up with the computer on, and time how long it takes to get to 90%.

Then, repeat this with the thing switched off, but switch on at your previously found time, if it's below 90% then it's slower, if it's above 90% then it's faster, and if it = 90%...

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Procrastinate Now!

 

[G0AOZ]

Thanks for the thought Crowley16 - might try that at some stage. So I take it you don't know the answer either

ROGER - G0AOZ.

 

[SuaveRick]

I've often wondered this too, please post your results.

 

[jakatz]

I will throw in my two cents worth to this . . .

I have no idea if it even similar, but here's my theory. I know both from experience and general knowledge that when you charge a mobile phone on an AC adapter, that when it is turned off, the charge is typically a trickle charge (which I beleive is better and keeps the battery healthier). If you ever experiment with it (on a phone or a laptop), you will find that when turned off, the device takes longer to charge.

But I am not sure what the actual scientific theory is in charging at a slower rate vs. a faster rate is (although it does make me curious as well).

Althogh it might be a bit off topic, and if it has any relevence, I just read the following FAQ on battery charging that may make interesting reading (or not):

Will "fast charging" my batteries reduce their life cycle?

Yes, the maximum number of charge cycles that your rechargeable batteries can endure will be somewhat less using fast chargers vs. slow overnight chargers. The cycle life attained is dependent on many factors including the rate of charging and discharging as well as the depth of discharge between charge cycles. In other words if you want to attain the highest number of charge cycles use a slow charger and begin recharging your cells before they are 50% discharged. You would be however, sacrificing the maximum performance and convenience your batteries are capable of and were designed for.

In our opinion it would be worth sacrificing the convenience of fast charging only if the replacement cost of your batteries were significantly higher. If you got only 300 charge cycles instead of 600 charge cycles your cost per charge would still only be 1 penny per charge instead of 1/2 penny per charge. Compare that to the cost of a throw-away alkaline cell of as much as $1 per cell. NiMH cells can supply as much power as hundreds of throw-away alkaline cells. NiMH cells cost much less to operate regardless of the ultimate number of charge cycles attained.