I’m working on a section of my thesis on the battery life of mobile phones which has been illuminated by the work of Ahmad Rahmati on ‘human-battery interaction’. Below is an extract from a first  draft of this chapter.  When I mention women’s capabilities I’m referring to the theoretical framework of the capability approach which I’m using in my research to critically examine the impact of smartphones on the lives and opportunities of socially excluded young women. 

---

Why do you hate your phone?
Mainly because of the battery…

Morgan’s response to the question of why she hated her phone was not unusual in this study: for many respondents poor battery life was a major annoyance. This is also possibly related to the fact that, for the 11 homeless women in this study, finding a place to charge their phones was difficult.

This is in part down to technological constraints. Battery life has not kept up with the speed of the phones themselves: “Battery capacity, in terms of volumetric or gravimetric energy density, improves at a much slower pace than computing capacity” (Rahmati et al. 2009 p.466). This is shown in the experience of respondents who reported that the battery life of their phones was less than a day. In contrast, two of the feature phone users in this study, Kayla and Rebecca reported a battery life of three to four days.

Jessica was 21 and homeless.
What’s the battery life [on your phone] like?
Crap.
Like a day?
Not even that, if you’re texting your friend for about an hour it goes down to 50%. And I don’t actually have a charger for it myself.

Tanya, 17, was also homeless and had resorted to paying a pound in central Brighton to get her phone charged for half an hour because the battery life was so poor. Zara had also paid to get her phone charged but related the fact that it needed charging regularly to the variety of functions the phone served for her.

Would it [battery] go in a day? half a day?
A day easily but thats because of all of the stuff that you use on there.
Did you ever pay to go and get it charged in town?
We have done yeah, like a pound or something.
Did it annoy you that you had to do that?
It is quite annoying as you pay enough for the phone.

Emma complained about the battery life on her iPhone, saying that it had gone down to half way already that day at the time of the interview at 10.30 in the morning. The field notes record an observation that her battery life might have been linked to her compulsive checking of her phone.

We talk about battery life and she says her charge is really bad. She has charged it fully that morning and it is gone down to halfway already even though it was only about 1030 in the morning when I interviewed her. She was fiddling with her phone constantly – just locking and unlocking it almost compulsively. When I asked her about this she says she’s looking at the time and checking on her battery life. She was talking about how rubbish her battery life was and she even mentioned that she thought it might be because of this fiddling about. 

Megan’s perception was that the battery life on her phone had declined since she first got the phone.

I’ve known my phone to go from fully charged to completely dead within two hours, watching films, playing music.
Has the battery life gone down a lot since you got it?
Yeah its probably halved.

Megan’s experience is related to the fact that the batteries used in the generation of smartphones used by women in this study start declining immediately after manufacture. A finding which was reinforced in Rahmati et al’s study.

Most mobile phones employ rechargeable Lithium-ion (Li-ion) or Lithium-ion polymer (Li-poly) batteries, which enjoy improvements over previous generations, such as nickel-cadmium (NiCd) and nickel metal hydride (NiMH)… An important drawback of Li-ion and Li-poly batteries is that they start aging immediately after manufacture, even if not used . Battery lifetime becomes noticeably shorter after several months of usage, and this was reported by participants in our four-month field trial. (Rahmati and Zhong, 2009 p.466)

In the same study the authors found that users were not making effective use of the power saving settings on their phones which might have increased the battery life.

While virtually all mobile phones provide user adjustable power-saving settings and other settings that impact battery life, they usually remain unused and ineffective. (ibid. p.475)

Other work by Rahmati et al. links larger overall levels of smartphone use and impact on battery use with Socio-economic status. They conducted a longitudinal study comparing iPhone usage among two groups of college students with different Socio Economic Status (SES) and found that users with lower socio-economic status had much higher overall usage of their phones.
On one hand, the iPhone offered the lowest SES users access to technology for information and entertainment that was used very frequently, much more than others at higher SES levels. For the women in this study this is related to their ‘digital exclusion’: less then half of respondents had their own computer so were invariably using their smartphones for more activities.

By relating complaints about battery life to a broader sense of ’poor perceived usability’ this study shows how this particular maintenance affordance might impact on women’s capabilities to lead lives they value. Firstly by interrupting their connectivity when their batteries run out and secondly the cost burden of payment for charging phones.

Rahmati, A., Tossell, C., Shepard, C., Kortum, P. & Zhong, L. Exploring iPhone usage: the influence of socioeconomic differences on smartphone adoption, usage and usability. Proceedings of the 14th international conference on Human-computer interaction with mobile devices and services, 2012. ACM, 11-20.
Rahmati, A. & Zhong, L. 2009. Human–battery interaction on mobile phones. Pervasive and Mobile Computing, 5, 465-477.