Author Topic: PPC640 Battery Life  (Read 2328 times)

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Offline chinnyhill10

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PPC640 Battery Life
« on: 04:37, 13 December 15 »
So tonight I had a second attempt at running my PPC 640 from 10 C cells.


People who follow me on Twitter will know last Saturday I tried it, but it only ran for a few seconds before one of the alkaline cells failed! So this week was attempt 2.


Fired her up and worked perfectly with both drives. I'd often heard the rumour that accessing the floppy caused the screen to dim but I saw no evidence of that.


I did extensive tests formatting disks, using Xcopy, as well as running Wordstar and QBasic. I really hammered the drive access far more than you would in real life as well.


90 minutes in the battery alarm started to sound occasionally when accessing the disk. But it was still running at 2 minutes 15. The alarm was screaming at all disk access (what a terrible design) but the machine was still running fine.


At that point I decided to measure the batteries and they had dropped to 1.2v per cell and were very hot (unsure if it was the PPC or the load on the batteries causing this). Tried to restart but it would not. Got a few seconds into booting and failed. Seems once you turn the machine off the strain of powering up again kills the batteries.


Still at least 2 myths have been dispelled. Firstly the battery life is far better than the 1 hour some sites claim and 2) at least my machine never dimmed the screen during disk access no matter how hard I pushed both drives.


Hard to see how it could meet the claimed 6 hour battery life Amstrad claimed in some adverts though unless you never accessed the floppy or pushed the CPU.
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Offline Bryce

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Re: PPC640 Battery Life
« Reply #1 on: 11:36, 13 December 15 »
If you got 2 hours out of it when hammering the drive, then at idle with screen brightness right down it probably would manage 6 hours. Amstrad, like all other manufacturers of battery operated gear like to abuse the term "up to" as they wish.

Bryce.

Offline chinnyhill10

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Re: PPC640 Battery Life
« Reply #2 on: 14:13, 13 December 15 »
If you got 2 hours out of it when hammering the drive, then at idle with screen brightness right down it probably would manage 6 hours. Amstrad, like all other manufacturers of battery operated gear like to abuse the term "up to" as they wish.

Bryce.


There's no such thing as screen brightness on the machine as there is no backlight. There is contrast which mat marginally impact the battery life although even when the batteries were at their lowest I couldn't make the battery alarm go off by turning it to maximum.


You may well get 6 hours *if* you don't need to save at the end of your session and *if* you haven't had to turn the machine off and on a few times. Certainly while the machine was running at 1.2v per cell, it wouldn't turn back on again. Must be a serious surge when it first starts up (hence one of the C cells blowing last week).
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Offline Bryce

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Re: PPC640 Battery Life
« Reply #3 on: 15:24, 13 December 15 »
Ok, then the screen wouldn't make a difference, but it wouldn't suprise me if the 6 hours was still done with the machine just idling. Were you measuring the battery voltage under load or open circuit?

Bryce.

Offline Gryzor

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Re: PPC640 Battery Life
« Reply #4 on: 17:32, 13 December 15 »
To be fair, it's not only Amstrad that did it, and even today's standards are far from approaching real-life scenarios :)

Offline MacDeath

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Re: PPC640 Battery Life
« Reply #5 on: 18:54, 13 December 15 »
just use a power adapter and don't waste chemicals on disposable batteries...  :doh:

Offline chinnyhill10

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Re: PPC640 Battery Life
« Reply #6 on: 20:39, 13 December 15 »
just use a power adapter and don't waste chemicals on disposable batteries...  :doh:


Isn't it blatantly obvious I was doing a test rather than using the batteries for the sake of it?  :doh:
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Offline MacDeath

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Re: PPC640 Battery Life
« Reply #7 on: 21:28, 13 December 15 »
Don't hit yourself on the head ...  :doh:

 ;D