"We need a 48V battery, about 100Ah" is how many custom lithium-ion battery pack requests start. It's a reasonable start, but it isn't a specification. Two packs that both match it can behave completely differently in your equipment: one trips its BMS on the first hard acceleration, the other runs all shift. The difference is in the details an RFQ either captures or leaves for someone to guess.
This is the checklist our engineering team works through on every custom pack request. Send as much of it as you have. Gaps are normal, and the last section explains what we do with them.
1. Electrical requirements
Voltage window, not just a nominal voltage. Give the minimum and maximum voltage your controller, motor drive or DC-DC converter accepts. A "48V" pack can be 51.2V LiFePO4 (16S, about 58.4V full) or 46.8V–51.8V NMC (13S or 14S). The window decides the chemistry and series count. See lithium battery pack voltage explained.
Continuous current. The current the pack must deliver for long periods, with the duration.
Peak current. The highest current and how long it lasts: motor start, lift, acceleration, inrush into capacitors. A 300A peak for 2 seconds is a very different design from 300A for 30 seconds.
Regenerative or charge current. If your equipment brakes regeneratively or lowers loads, say how much current it returns and when. A full pack can't absorb much regen current, so the BMS and controller need a plan for it.
Runtime or energy. Give the runtime you need under a described load, or the energy in Wh. Amp-hours alone can mislead across voltages; Wh = nominal voltage × Ah.
Duty cycle. A load profile beats an average. Even a rough table (idle, cruise, peak, with times) lets us size cells for heat and life, not just capacity.
2. Mechanical requirements
- Envelope: maximum length, width and height, and any keep-out zones.
- Weight: a maximum, a target, or a minimum (some equipment uses the battery as counterweight).
- Mounting: how the pack is fixed, its orientation, and whether it's removed for charging or service.
- Connectors: the power and communication connectors you use today, or let us propose them.
- Enclosure and ingress: the ingress protection your equipment needs, plus any wash-down, dust or chemical exposure.
3. Environment
- Operating and storage temperature range, including the coldest temperature at which the pack must charge (lithium cells need reduced current or heating below freezing).
- Vibration and shock: describe the equipment and how it moves, or give a test profile if you have one.
- Humidity, condensation and altitude where relevant.
- Expected service life in years and cycles.
4. Charging
- Existing charger (make, model, output voltage and current), or whether you need one.
- Charging pattern: one full charge a day, opportunity charging at breaks, or continuous float as backup power.
- Charging location and temperature.
- Any charger communication with the BMS.
Lead-acid chargers with equalization or float stages aren't suitable for lithium packs. Our lithium battery charger catalog is organized by chemistry, series count and output voltage.
5. Communications and BMS behaviour
- Protocol: CAN, SMBus, RS-485 or a simple discrete signal.
- What your system needs from the pack: state of charge, current limits, temperatures, fault codes.
- What should happen at each fault: warn, limit current or disconnect.
- Any wake-up, sleep or shipping-mode needs.
See battery management systems for custom packs.
6. Compliance and transport
List any safety, transport or market standards your product has to meet, and the documentation you need from your battery supplier. The required testing and documentation scope is confirmed per program in the quote, so list them early: they affect the design, the schedule and the cost.
7. Quantities and forecast
- First-order quantity.
- Annual volume, and how it ramps.
- Prototype and pilot quantities.
- Expected program life.
Catalog reference designs start at 10 units and custom designs at 25 units. We supply OEM, industrial and commercial programs; we don't sell single batteries to consumers.
The copy-and-paste RFQ checklist
APPLICATION
- Equipment and what the battery powers:
- Existing battery (if replacing), with part number or drawing:
ELECTRICAL
- Voltage window (min / max the equipment accepts):
- Continuous current and duration:
- Peak current and duration:
- Regenerative / charge current returned by the equipment:
- Runtime under a described load, or energy (Wh):
- Load profile (idle / normal / peak, with times):
MECHANICAL
- Maximum dimensions and keep-out zones:
- Weight limit (max, target or minimum):
- Mounting and orientation:
- Power and communication connectors:
- Ingress / wash-down needs:
ENVIRONMENT
- Operating temperature range:
- Charging temperature range:
- Storage temperature range:
- Vibration and shock (description or profile):
- Service life (years / cycles):
CHARGING
- Existing charger or new one needed:
- Charging pattern (daily / opportunity / float):
COMMUNICATIONS
- Protocol and required data:
- Fault behaviour required:
COMPLIANCE AND TRANSPORT
- Standards and documentation your product requires:
QUANTITIES
- Prototype / pilot quantity:
- First-order quantity:
- Annual volume and ramp:
- Target dates:What we do with missing data
Few RFQs arrive complete, and that's fine. When something is missing, we:
- Make an explicit assumption and write it into the proposal, so you can correct it before the design is frozen.
- Propose a measurement where the load is unknown: for example, logging current on an existing machine over a shift.
- Start from a reference design close to your requirements, then adjust capacity, connectors, BMS communications or enclosure.
- Separate what's fixed from what's flexible, so you know which choices change the quote.
The answers that most often change a design late are the peak current, the coldest charging temperature, the connector and the minimum weight. If you only have time to pin down four things, start there.
From RFQ to production
A typical program runs through requirements, pack design, prototype and validation, pilot build, then volume production under change control. Lead times run from weeks to months depending on design scope, cells, validation and volume, and we confirm them in your quote. See battery pack design and engineering and OEM battery pilot production.
Lithium Battery Company has designed and built custom lithium battery packs since 2014, with hundreds of thousands produced for OEM programs.
Request a custom battery pack quote · Custom lithium-ion battery packs · LFP vs NMC chemistry
FAQ
What information do I need to get a custom lithium battery pack quote?
At minimum: the application, voltage window, continuous and peak current, runtime or energy, available space, operating temperature, charger, and first-order and annual quantities. We can make and document assumptions for anything missing.
What is the minimum order for a custom lithium-ion battery pack?
Catalog reference designs start at 10 units and custom designs start at 25 units.
Why do you need peak current as well as continuous current?
Peak current sets the rating of the cells, busbars, fusing, contactors and BMS. A pack sized only for average current can trip its protection during motor starts or lifts.
How long does a custom battery pack take?
Lead times run from weeks to months depending on design scope, cells, validation and volume. We confirm the schedule in your quote.