Buyer's guide

Buying aircraft batteries: Ni-Cd, lead-acid, lithium-ion and ELT packs — part numbers, shipping, age and paperwork

By the MG AVIATION TECH team · Published · 9 min read

A battery line looks simple on a parts list: one part number, quantity one. It is not. The part number is tied to a chemistry and an installation approval, the box travels as dangerous goods, the battery ages on the shelf in a way a condition code does not show, and several kinds of battery carry a replacement date of their own. This guide is for airline, MRO and business aviation buyers of main and APU batteries and of the small batteries inside emergency equipment: what to specify, what to ask, and what to check before the battery goes on the aircraft.

The short answer

  • Buy the part number your IPC, CMM or STC calls out. Chemistry, voltage and capacity are not enough to make two batteries alternates, and a different chemistry needs its own installation approval.
  • Ask how the battery will ship: which UN entry, and whether it is charged or discharged, filled or not. That decides the carrier, the route and the date it reaches you.
  • Ask for the date of manufacture and, for a battery that has been sitting, what was done to it since. The maker's manual decides whether it needs a charge or a capacity test before installation.
  • For ELT and beacon packs, ask for the expiry date printed on the pack. Time the pack spends on a shelf can eat into it.

Which batteries a transport or business aircraft buys

Two groups turn up on parts lists. The first is the ship's batteries, the main and APU batteries that power the electrical system on the ground, start the APU or engines and back up essential buses. The second is the small batteries built into equipment: emergency locator transmitters (ELTs), underwater locator beacons on the flight recorders, emergency lighting power supplies and portable lights.

BatteryWhere you meet itCurrent TSO for the articleHow it is described for transport
Vented nickel-cadmium (Ni-Cd)Main and APU batteries on many turbine airliners and business jets; often maintained cell by cell in a battery shopTSO-C173 / C173a (RTCA DO-293 / DO-293A)Batteries, wet, filled with alkali, electric storage, UN2795, Class 8
Valve-regulated lead-acid (VRLA, "sealed")Main and emergency batteries on many business and general aviation aircraftTSO-C173 / C173aBatteries, wet, non-spillable, electric storage, UN2800, Class 8, when the battery meets the non-spillable conditions
Vented (flooded) lead-acidOlder installationsTSO-C173 / C173aBatteries, wet, filled with acid, electric storage, UN2794, Class 8
Rechargeable lithium-ionMain and APU batteries on newer types such as the Boeing 787; lithium-ion replacements approved by STC for some older typesTSO-C179b (RTCA DO-311A); the 787's battery was certified under FAA special conditions 25-359-SCLithium ion batteries including lithium ion polymer batteries, UN3480, Class 9 (UN3481 when contained in or packed with equipment)
Non-rechargeable lithium packsELT battery packs, underwater locator beaconsCovered with the equipment's approval; one beacon maker lists TSO-C142b for its batteryLithium metal batteries including lithium alloy batteries, UN3090, Class 9 (UN3091 when contained in or packed with equipment)

The FAA's original TSO-C173 is for "permanently installed rechargeable nickel-cadmium and lead-acid batteries" that power aircraft equipment, "including emergency and standby systems, and electrical power to start aircraft engines or auxiliary power units." Its revision, TSO-C173a, adds nickel-metal hydride and calls up RTCA DO-293A, as does the European ETSO-C173a. Rechargeable lithium cells, batteries and battery systems are approved separately under TSO-C179b, which uses RTCA DO-311A.

If you are buying one battery for a piston single, this is not your market: those batteries are sold as catalog items by aviation retailers, usually by aircraft model. The rest of this guide is about batteries bought against an operator's or MRO's parts list.

Part number and chemistry: why "same voltage, same size" is not an alternate

A TSO says a battery meets a minimum performance standard. It does not say the battery may go on your aircraft. TSO-C173 requires the maker to state it in the installation limitations: "TSO articles must have separate approval for installation in an aircraft." The same document notes that nickel-cadmium and lead-acid battery safety concerns "include the possibility of fire, and venting violently."

In practice that means three things for the RFQ:

  • Quote the number the aircraft documents call out. A Ni-Cd battery and a lead-acid battery of the same voltage are not alternates, and a lithium-ion replacement for either is a design change that comes with its own STC or OEM approval and installation instructions. The battery installation, charging and venting are part of the approval, not just the box.
  • Expect several numbers for one battery. The NTSB's report on the 2013 Japan Airlines 787 battery fire gives the APU battery's maker part number, LVP65-8-402, and adds that "Boeing's part number for the battery model at the time of the incident was B3856-901." ELT packs are the same: one six-year Kannad pack is listed as S1840510-01, BAT200 and 40510-01, plus a distributor number. List the number from your IPC and say whether the maker's equivalent is acceptable. Our guide to alternate and interchangeable part numbers covers how to write that.
  • A pack fits a family of units, not every unit. An Artex 452-0133 pack, for example, is listed for the C406-1, C406-2, C406-3, B406-1, B406-2, B406-4, 110-406 and 110-406NAV ELTs. Put the unit's model and part number on the RFQ line next to the battery number, so the seller can check the pairing. The same goes for recorder beacons: since March 2015, newly manufactured underwater locating devices have had to meet the 90-day operating life of TSO-C121b, and a 30-day and a 90-day beacon battery are not the same item.

How a battery ships: filled, charged, and which UN entry

Every battery in the table above is regulated for transport, and the entry depends on chemistry and construction, not on the part being "aircraft equipment." What the buyer should know before the purchase order:

  • Vented Ni-Cd batteries can ship discharged. Saft's operating and maintenance manual for its aircraft Ni-Cd batteries (ATA 24-30-99) says: "Saft batteries are shipped discharged," and its chapter on storage, which includes transportation, has them kept "filled and discharged." It then lists what must happen before the battery goes into the aircraft: "A visual inspection, torque check, charge procedure, electrolyte check, and insulation test." A new Ni-Cd battery is not ready to install out of the box; budget shop time.
  • VRLA batteries can arrive charged. Concorde's component maintenance manual for its RG series says the batteries "are serviced and charged at the factory prior to shipment," and that the batteries are classified as non-spillable and "comply with hazardous shipping exceptions" of the IATA, IMDG and U.S. DOT rules. Under 49 CFR 173.159a, a non-spillable battery must, among other conditions, be marked "NON-SPILLABLE" or "NON-SPILLABLE BATTERY" and be loaded or braced so as to prevent damage and short circuits.
  • Lithium batteries are Class 9, and a spare lithium ion or lithium metal battery shipped on its own (UN3480 or UN3090) is forbidden as cargo on passenger aircraft in the U.S. Hazardous Materials Table. A replacement ELT pack is the case most buyers meet: the two packs named above are listed as UN3090, Class 9.

What this changes — a trained shipper, specified packaging, a shipper's declaration, fewer flights, extra charges — and the questions to ask on the RFQ are in our guide to dangerous goods in an aircraft parts order. For batteries the minimum is: the UN number and proper shipping name, whether the battery ships charged or discharged, and whether DG packing is included in the price.

Age, storage and the check before installation

A battery ages from the day it is made, and "NE" on a quote says nothing about how long it has been on a shelf or how it was kept. The manufacturer's manual for that battery sets the rules. Two published examples show how different they are:

Vented Ni-Cd (Saft OMM 24-30-99, Jan 2014)VRLA (Concorde CMM 5-0171, Rev. Q, Dec 2018)
State in storageLong-term storage: "stored filled and discharged"Charged; self-discharges, so the open circuit voltage (OCV) drops over time
Storage life10 years in sealed packaging at 20 °C ± 15 °C and under 70% humidity; the standard cardboard packaging "is considered unsealed and allows 2 years of storage"No storage life stated; boost charge when a 24 V battery's OCV falls to 25.0 V
Before installationCommissioning charge and checks; if stored longer than 3 months, the manual's "servicing after discharged storage" procedureMeasure OCV: 25.5 V or more, install; 25.0–25.5 V, boost charge first; below 25.0 V, capacity test first
Long storage—"Batteries in storage for longer than 24 months must be capacity tested" before being placed in service
Storage room"Lead batteries must not be stored in the same room"May be stored and serviced in any battery facility, including Ni-Cd shops

The numbers belong to those documents and revisions; use the current manual for the part number you buy. The purchasing point is general: ask for the date of manufacture and, for a battery that is not fresh from the maker, the date and result of its last charge or capacity check. Two quotes for the same number can be two very different batteries. For shelf-life items in general, our guide to aircraft parts shelf life explains how to ask for remaining life.

Dated batteries: the ELT rule as an example

Some batteries carry a replacement date the operator must track. For ELTs on U.S.-registered aircraft, 14 CFR 91.207(c) says the batteries "must be replaced (or recharged, if the batteries are rechargeable)— (1) When the transmitter has been in use for more than 1 cumulative hour; or (2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, as established by the transmitter manufacturer under its approval." It continues: "The new expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record."

For a buyer, that makes the pack's date part of the offer. The two packs above are sold as five- and six-year packs; ask how the maker counts that life, because if it runs from manufacture, a pack that sat on a shelf gives you less time on the aircraft. Ask for the manufacture or expiry date printed on the pack, and whether the kit includes what the maker supplies with it: one six-year Kannad kit, for example, comes with a replacement O-ring, a desiccant pack and self-locking nuts.

New or overhauled, and the paper that should come with it

Small lithium packs are bought new. Main and APU Ni-Cd batteries are also serviced and overhauled in battery shops, and are sometimes sold overhauled. An overhauled battery is a maintenance item: the release should say what was done. On a U.S. release that is an FAA Form 8130-3 issued as a return to service by the repair station that did the work; for an EU-registered aircraft, an EASA Form 1 or a dual release. Ask for the work order or capacity test record behind the tag as well. Which certificate your aircraft's registry needs is explained in 8130-3 vs EASA Form 1.

From our quote data

In supplier quotes we received between June and September 2026, batteries, battery packs and battery kits made up 525 priced offer lines for 68 different part numbers. 69% were offered new (NE), 10% overhauled (OH), 6% new surplus and 4% serviceable. An FAA 8130-3 was named on 30% of battery lines and an EASA Form 1 on 15% (a dual release counts in both); 43% stated no certificate at all.

A line that names no certificate is not a line with none; it is a question you have to ask before you compare prices. The same goes for the condition code: the difference between NE and NS, and what OH and SV promise, is in our guide to condition codes.

Buyer's checklist for a battery line

On the RFQ and POWhy
Battery part number exactly as in the IPC, CMM or STC; whether the maker's equivalent number is acceptableChemistry and installation approval go with the number; one battery can carry several numbers
For packs: the unit model and part number the pack is forA pack fits a listed family of ELTs or beacons, not every unit
Condition (NE, OH, SV) and, for OH, what work was doneAn overhauled battery is only as good as the work and test behind it
Certificate: 8130-3, EASA Form 1, dual release, or the maker's CoC43% of battery lines we received named none
Date of manufacture; expiry date on ELT and beacon packsShelf time can eat into rated life; ELT battery dates must be marked and recorded
State at shipment: charged or discharged, filled or not; last charge or capacity checkDecides whether the battery needs a boost charge, commissioning or a capacity test before installation
UN number, proper shipping name, class; DG packing included or extraSets the carrier, the route and the lead time to your dock
What the kit contains (seals, desiccant, hardware, connectors)A bare pack without its kit parts may not be installable

On receipt, check the number on the battery label against the PO, the date against the certificate, and the package for damage or leaking electrolyte before it goes to the battery shop. Our receiving inspection guide covers the rest of the dock check.

Send your battery lines with the questions already asked

Send your RFQ to [email protected] in the file you already have — Excel, PDF, a scan or the email body, five lines or five hundred — with the battery part number, the unit it is for, the certificate you need and a note asking for the date of manufacture. Your inquiry will be reviewed by a specialist within one business day.

Send your RFQ →

In our client portal, RFQ Radar, every quoted line shows its condition, certificates, lead time in days and the country it ships from, and a purchase order there has a "certificate needed" tick on each line and a note, so a date or paperwork requirement travels with the order.

Before you buy, check what certificates and trace come with each part. Aircraft on ground? See how our 24/7 AOG desk works.

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