FORKLIFTS & LIFTING EQUIPMENT – BATTERY MANAGEMENT
extremes, and Li-ion
batteries intended
for cold applications
will require heaters and
cooling fans, but these draw
power even when the equipment
is idle, and it is vital to maintain su cient
power to the BMS in order to protect the
battery. If this is not done, the battery
could enter a shutdown state that may not
be recoverable, and eventually the battery
may become unstable.”
Goss says that regular visual
inspection, and an annual test by a
specialist technician, should be the only
maintenance required for Li-ion. In fact,
repairs should only be attempted by a
specialist.
THE ACID TEST
With all the interest surrounding
lithium-ion, it “would be wrong” to think
that lead-acid battery development
has stagnated because “considerable
advances in lead-acid battery technology
have also occurred”, including reducing
maintenance, increasing charge rate and
capacity, and permitting opportunity
charging.
Goss reports: “With lithium-ion
batteries there is likely to be little loss
of truck performance as the state of
charge declines. Historically, some
trucks with lead-acid
batteries exhibited a loss
of performance roughly
proportional to the state
of charge. This was bad for
productivity, but provided warning to
the operator that it was time to head
for the charging station. Modern trucks,
especially those with AC drives, are much
less prone to this.
“Charging of PbA should be carried out
in a dedicated and well-ventilated area,
as detailed in BS EN 62485-3:2014. This
is because hydrogen gas will be emitted
during charging, and this represents an
“Charging of PbA should be carried out
in a dedicated and well-ventilated area”
David Goss, technical manager, British Industrial Truck Association
explosion hazard. One of the bene ts
of Li-ion is that no gas is emitted during
charging. Also, unlike Li-ion, PbA batteries
can be sensitive to the rate and duration
of charge, and also to the level of charge
present when charging commences.
Unless the battery and charger
manufacturer have speci cally stated
otherwise, it is prudent to commence
charging when the state of charge is
approaching 20%, and to continue
charging until full.
“Cell balancing, or equalisation, is
required when di erent cells develop
slightly di erent power characteristics. On
Li-ion, the BMS does this automatically.
With lead-acid batteries, sulphate deposits
on the plates may cause some of the cells
to hold only a partial charge when others
are fully charged. Typically, equalisation
charging is a longer process than an
ordinary charge, but the requirements
vary according to equipment type and
application. The expertise of your battery
supplier is an invaluable resource.”
Goss adds that the battery is an
expensive item to replace, so investment
in best practice is well repaid. Correct PPE
is also essential, due to the risk of electric
shock and potential contact with acid and
gases.
“Topping up, also known as watering,
must only be done with clean distilled
water, as any impurities will rapidly
degrade the battery. Watering can be
carried out manually to each cell, with
a low-pressure oat in each cell and
single connection point or, most rapidly,
with a high-pressure system which
June 2019 www.operationsengineer.org.uk 19
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