Careful – otherwise it’ll go bang!

Battery-operated devices and systems can be found in many places in buildings (e.g. for emergency lighting systems, UPS systems, electric ants, forklift trucks, cleaning machines, etc.). Today, lead-acid batteries are mostly used, but nickel-cadmium (NiCd) and nickel-oxide-metal hydride (NiMH) and lithium-ion batteries are also in use. The batteries are usually charged at individual charging points, charging stations or charging rooms.

Recharging batteries often takes place quietly and silently in the background, but this process also harbors a number of dangers, such as the risk of chemical burns from the electrolyte, the risk of explosion due to the formation of explosive gases or electrical hazards (e.g. due to short circuits).

If handled incorrectly or under the wrong conditions, it can be dangerous, loud and very expensive. In this article, we show you how you can minimize these risks.

What dangers are associated with rechargeable batteries?

Risk of explosion:
Depending on the design (closed, sealed, gas-tight) and the level of charging current, more or less explosive hydrogen gas (= oxyhydrogen gas – produced by electrolysis during the charging process) can escape during the charging process. If this gas comes into contact with an ignition source (e.g. a spark is sufficient), it burns explosively (hence the name “oxyhydrogen gas”).

Risk of chemical burns:
The electrolyte (also known colloquially as “battery acid”) is very acidic (e.g. sulphuric acid) or alkaline (e.g. potassium hydroxide solution) and can cause serious injuries if touched (the “fuller” the battery is charged, the more corrosive the acid/alkali is!!).

Risk of electric shock:
There is direct current (DC) between the poles of the batteries – this is much more dangerous than alternating current and can cause serious injury from 60V and requires additional safety measures.

How can the risks be reduced?

General measures:

• Clearly mark loading points (floor markings, signs, pictograms, etc.) – see below
• Place a clearly legible operating instruction in the vicinity of the danger zone (= compact summary of the most important safety measures and behaviors for commissioning, use and maintenance)
• Always lock technical operating rooms – only allow access to instructed and trained personnel

Explosion hazard:
Ventilation is essential, as the oxyhydrogen gas reaction is possible from a concentration of approx. 4 % by volume in the air. Therefore, hazard identification and assessment (workplace evaluation) is required by law before commissioning the charging station. The measures specified in this EX protection document (in accordance with VEXAT – Ordinance on Explosive Atmospheres) must be complied with.

As a rule, these measures bring the most security gains:

• Always ensure sufficient natural or mechanical ventilation – exhaust air must be discharged directly to the outside and not into other ventilation ducts
• Sufficient distance from flammable or explosive substances (observe manufacturer, legal and insurance requirements!!)
• Chargers may only come into contact with non-combustible materials (e.g. concrete, metal, etc.)
• Keep naked flames, sparks, glowing objects or other sources of ignition away from the vicinity (less than 50 cm away) of gas outlets
• The floor must not exceed a maximum el. resistance of 100MΩ must not be exceeded (electrostatic charging = sparks possible)
• Do not disconnect the battery immediately during or after charging (sparking/arcing possible = risk of explosion) – it is better to wait a while to allow the oxyhydrogen gas to dissipate
• Avoid deep discharging the batteries – when charging deeply discharged batteries (<20% of the nominal capacity), high charging currents occur which cause increased oxyhydrogen outgassing

Risk of chemical burns:

• Repair and maintenance work should only be carried out by trained specialist personnel
• wear appropriate personal protective equipment (skin, face, eye protection, etc.)
• The floor must be acid-resistant

Risk of electric shock:

• Regularly inspect and maintain chargers and systems in accordance with the Check and maintain electrical protection regulations (ESV) and workplace regulations (AStV) (manage appointments easily and conveniently in the MyBuilding24 app)
• Measure voltage level before contact
• Provide protection against direct contact (e.g. covers, insulation, distance)
• Above 120V, additional measures against indirect contact are required (e.g. potential equalization, automatic disconnection)
• Use dissipative and antistatic safety shoes

What emergency measures apply in the event of eye or skin contact with the electrolyte?

• Keep an eyewash basin or running water nearby
• In case of eye contact: rinse with plenty of water for a long time and seek medical advice immediately
• In case of skin contact: rinse with plenty of water for a long time – seek medical advice if skin irritation is visible

Which prohibition, warning, mandatory and escape signs identify a loading system (symbols can be used in accordance with the labeling ordinance or ÖNORM EN ISO 7010)?

The above symbols must be used – others can be added depending on the hazard evaluation.

To make sure you don’t miss any appointments in future, download the MyBuilding24 app, where you can record all your devices and systems that require inspection and maintenance and manage the associated appointments, and always be on the safe side with a complete list of maintenance work available at all times.

Glossary – Legal provisions:

Employee Protection Act – ASchG:
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10008910

Workplace Ordinance – AStV:
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10009098

Explosive Atmospheres Ordinance – VEXAT:
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=20003475

Labeling Ordinance – KennV:
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10009067

Electrical Safety Ordinance – ESV 2012:
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=20007682

Information from AUVA:
https://www.auva.at/cdscontent/load?contentid=10008.733797&version=1583926961

Standards:

• ÖVE/ÖNORM EN 62465-3:2015 – Safety requirements for batteries and battery systems
• ÖVE EN IEC 62485-2:2019 – Safety requirements for secondary batteries and battery systems
• ÖVE E 8351:2016 – First aid in case of accidents caused by electricity
• ÖNORM EN ISO 7010:2015 – Graphical symbols, safety colors and safety signs