Power consumption hit with card left installed?

[MartinG]

Does anyone know whether there's a power consumption hit with a WiFi card left installed in a S7/nB when not in use? :confused:

The card seems to have to be 'switched on' by the browser, etc. before it becomes active - rather than being live the whole time so I suspect that any additional current consumption hit will be relatively low - but unfortunately the S7/nB doesn't report current consumption as the 5/mx does and so it's difficult to monitor...

Given the option - and assuming that power consumtion isn't significantly hit - I'd rather just leave my Buffalo card in the machine the whole time. I don't use the PCMCIA slot otherwise and the low profile for this card makes it a viable option. It'll also make ad hoc WiFi sniffing (in all senses...) much easier! ;)

Any thoughts anyone?

Cheers,
Martin

[sbedford]

Should be fairly easy to determine using battery monitor such as ChaDis 7 which is freeware:

http://www.millican.info/Home/chadis7.htm

[MartinG]

Well you'd think so - but ChaDis7 doesn't report the current consumption directly AFAIKS. So yes, it'd probably be possible to carry out experiments with the card in v's with the card out - but you'd have to have your machine doing nothing else whilst you were measuring for a few hours (I guess) so that the results were fairly meaningful...

I can feel a little current measuring app. coming on... :cool:

[sbedford]

I don't think the Series 5 etc actually measure current. The current is calculated: cpu load, memory use, backlight, serial link, CF access etc. I assume the netBook would also not have circuitry to meaure current. However, noting voltage readings even over an hour should give a pretty good idea. I might try it (for no card, Cisco Aironet, and Psion Gold Card) and post results

[sbedford]

The attached file shows a graph derived from Chadis data. The dark blue line is without card fitted. The pink line is with Cisco Aironet fitted but not used. The yellow line is with Cisco fitted and doing one ping on Psion at start. The pale blue line is with continuous pings (about one every thirty seconds).

The same software was running on the netBook during whole period of tests. Screen was left on with ChaDis in the foreground.

So it does not appear as though there is a significant power consumption hit with a WiFi card left installed in a S7/nB when not in use.

[MartinG]

Many thanks for that - seems conclusive enough that having the card in make no (or negligible) difference. Excellent...

Thanks again,
Martin

[fladda]

Lucent Orinoco PCMCIA 802.11b card (Hermes Chipset) has a standby current of around 9mA. This appears to be in line with the results noted above.

Compared to the Rx and Tx currents of 185mA and 285mA, the sleep current appears negligible. Leave the card plugged in, unless you are going to that elusive 8 hour battery life !

Prism2 cards have a 20mA sleep current. That's 'progress' for you.

Ralph