  Solar home systems (SHS) provide low-cost electricity access for rural
off-grid communities. Batteries are a crucial part of the system, however they
are often the first point of failure due to shorter lifetimes. Using field
data, this work models the degradation of lead-acid batteries for different SHS
use-cases, finding the dominant ageing mechanisms in each case. Corrosion is
the dominant ageing mechanisms in all cases apart from the highest use case.
This is caused by extended time at high state of charge (SOC) and hence high
voltage. A new voltage control scheme is proposed for one of the use cases
dominated by corrosion, whereby the number of days between full recharges
varies depending on the degradation mechanisms the battery experiences.
Simulating the new voltage control scheme yields a 25% increase in battery
lifetime whilst ensuring no loss of load to the user.
