Electric aerial platform batteries: lead-acid or lithium, charging and maintenance

In short: most electric platforms still run on lead-acid batteries (flooded or AGM). They last longer if they are always fully charged, kept above 80% state of charge and, for flooded batteries, topped up with distilled water after charging. Lithium needs almost no maintenance and accepts short charges, but it can only be fitted with the manufacturer's approval.

Batteries are the heart of an electric platform and one of the most expensive parts to replace. According to JLG, almost every battery that dies early dies for the same four reasons: poor charging, the wrong tests, too much or too little water, and freezing. All of them can be prevented with a routine.

What batteries do electric platforms use?

Flooded lead-acid (liquid acid)

This is the classic deep-cycle battery: cells with caps, sulphuric acid diluted in water and lead plates. It is rugged and the cheapest to buy, but it loses water with every charge and releases hydrogen at the end of the charge. It needs distilled water and, from time to time, an equalising charge.

AGM and gel (sealed lead-acid)

The electrolyte is held in a glass-fibre mat (AGM) or in a gel. It takes no water and releases almost no gas, because it recombines it internally, but it is not foolproof: if overcharged it can vent gas through its valves. It is standard on the 1930ES and ES2632 scissor lifts (4 × 6 V) and on the E450AJ articulating boom (8 × 6 V, 48 V system). The E300AJP articulating boom uses eight 6 V, 305 Ah deep-cycle batteries.

Lithium (LFP)

Lithium iron phosphate batteries come with a management system (BMS) that protects the cells. They take no water, need no equalising and keep their performance until the charge runs low. JLG now offers lithium as an option on several ES scissor lifts and fits LFP as standard on the EC450AJ compact articulating boom, with integrated heating so it can charge below zero.

How to charge without damaging the battery

• Charge to full. Let the charger finish its cycle. A lead-acid battery that spends a long time below 80% state of charge starts to sulphate, and sulphation gradually steals capacity.
• Avoid short charges when the battery is low. On lead-acid, plugging the charger in and out for 20 or 30 minutes when the battery is already low is one of the most harmful habits. On lithium, top-up charges are allowed.
• Don't wait for it to run flat. Fully discharging before charging is a myth that comes from old nickel-cadmium batteries. Don't discharge more than 80% of the capacity.
• Plug the machine in whenever it is not working, especially in cold weather.
• Use a short extension lead with an adequate cross-section. A very long cable or a small generator can prevent a full charge.
• Use the right charger. It must be set for the type of battery fitted (flooded, AGM, gel or lithium). AGM and gel need temperature-compensated charging.
• Charge in a ventilated area. Lead-acid batteries release hydrogen and oxygen, especially near the end of the charge. Open the battery compartment lid before charging and keep flames, sparks, welding and cigarettes away.

A new lead-acid battery does not deliver its full capacity straight away: AGM and gel batteries get there in fewer than 20 cycles, and flooded batteries can take 50 to 100 cycles.

Distilled water and equalising (flooded batteries only)

• Add water only after a full charge. Before charging, only if the plates are exposed, and only enough to cover them.
• Use only distilled or deionised water. Tap water contains minerals, such as iron, that damage the battery. Never add acid.
• Don't fill to the top. Top up to about 3 mm below the vent well. An overfilled battery spills acid through the caps while charging.
• Equalise only when needed. Equalising is a controlled overcharge carried out by the charger. It is done when, after a full charge, the specific gravity stays below 1.235 or varies by more than 0.030 between cells. Measure the specific gravity every hour and stop when it no longer rises. Never equalise AGM or gel batteries.

Maintenance plan: daily, weekly and monthly

To clean, use a solution of baking soda and water (about 60 ml per litre), without letting any liquid into the cells, then rinse with water and dry. Don't test deep-cycle batteries with starter-battery testers: they are not suited to this type and can condemn a battery that is still good. Preventive maintenance of the platform and the pre-use check complete this routine.

Winter and long periods of storage

Cold reduces capacity: at −18 °C a flooded lead-acid battery delivers about half the capacity it delivers at 27 °C. And a discharged battery freezes much more easily than a charged one, because its electrolyte is closer to plain water. A frozen battery can crack and must not be charged.

Before a long period out of use:

1. Charge the batteries fully.
2. Disconnect them from the machine (main isolator) to avoid parasitic loads.
3. Keep the machine somewhere dry and cool, sheltered from the weather.
4. Check the charge every 4 to 6 weeks on flooded batteries and every 2 to 3 months on AGM or gel. Recharge when it drops to 70% (flooded) or 75% (AGM and gel).
5. Give a full charge before going back to work.

In hot weather (above 32 °C) batteries self-discharge faster, so check them more often in summer.

Signs that a battery is reaching the end of its life

• Run time has dropped a lot, even after full charges.
• The charger does not reach the end-of-charge voltage, or the cycle takes much longer than before.
• One battery in the set has a resting voltage more than 0.3 V different from the others, even after equalising.
• On flooded batteries, the specific gravity of one cell stays well below the others after equalising.
• A swollen or cracked case, acid leaks, or corrosion that comes back soon after cleaning.
• In a discharge test, the set delivers less than half its rated capacity.

Voltage-based charge indicators can be misleading. Before replacing, a full diagnosis of the battery set and the charger is worthwhile.

Safety when working with batteries

• Wear acid-resistant gloves, goggles or a face visor and an apron. Remove rings, watches and metal chains.
• Use insulated tools and never put tools down on top of the batteries.
• Treat the area within about 1 m of a battery on charge as a hazardous zone. Hydrogen is explosive between 4% and 75% in air.
• After charging, wait at least 20 minutes before handling flooded batteries.
• When disconnecting, remove the earthed terminal first and reconnect it last.
• If acid gets on your skin or in your eyes, rinse with plenty of water and seek medical help. Small spills can be neutralised with baking soda and water.
• Used batteries are hazardous waste: hand them to your supplier or to a licensed operator.

Replace with identical batteries or switch to lithium?

When replacing, use batteries with the same characteristics and the same weight as the originals, as given in the machine's manual. On many electric scissor lifts the batteries are part of the counterweight and count towards stability, and the manuals forbid fitting lighter batteries. So replace the complete set and don't mix new batteries with used ones.

Lithium has clear advantages: almost no maintenance, faster charging, short charges without damage, and no water or acid. But a do-it-yourself conversion is a modification to the machine. It requires batteries, a charger and a BMS compatible with the control system, restoring the weight when the batteries count towards stability, and the manufacturer's written approval. Without these, you may compromise the machine's stability, warranty and compliance. If you want lithium, the simplest route is a new machine that comes with it from the factory, or checking with us whether there is a JLG-approved kit for your model.

How Trapézio de Prismas can help

We are the official JLG dealer in Portugal and we service electric platforms. We can:

• supply batteries and parts with the right specifications for your machine;
• include the batteries in the preventive maintenance plan.

You can find the manuals at JLG manuals. For service, request a service quote or get in touch.