Shopping for a lithium battery in NZ and drowning in numbers? 12V or 24V or 48V, 100Ah or 200Ah, kWh, LiFePO4, BMS ratings - this guide cuts through it. It is the same advice we give customers over the counter in Tauranga every week, written down.
One thing most guides miss: lithium batteries are not just a campervan thing. We build lithium power systems across three very different worlds - 12V for motorhomes, caravans and utes, 24V for bigger vans, buses and boats, and 48V for homes, tiny homes and off-grid cabins. The right battery depends entirely on which world you are in, so this guide covers all three.
Why lithium (LiFePO4) beats lead-acid for almost everyone
Nearly every lithium battery worth buying - from a camper battery to a home powerwall - is LiFePO4 (lithium iron phosphate). Compared with AGM or lead-acid:
- You can actually use the whole battery. A 100Ah lithium gives you close to 100Ah of usable capacity. A 100Ah AGM gives you about 50Ah before you start shortening its life.
- It lasts 5 to 10 times longer. Quality LiFePO4 cells are rated for 3,000 to 6,000 cycles. AGM is typically 300 to 600. On a home battery cycled daily, that is the difference between a decade of service and a replacement every couple of years.
- It weighs half as much. Our 12V 100Ah lithium is around 11 to 12kg. The AGM equivalent is 27 to 30kg.
- It holds voltage under load. Your inverter, coffee machine or trolling motor keeps running strong to the bottom of the charge instead of sagging.
The only places lead-acid still makes sense: engine starting, and rock-bottom-budget builds where weight and lifespan genuinely do not matter.
Ah, volts and kWh - the 30-second translation
Amp-hours (Ah) by themselves do not tell you how much energy is in a battery - you need the voltage too. Multiply them and you get watt-hours (energy):
- 12V 100Ah = about 1.28kWh
- 12V 200Ah = about 2.56kWh
- 12V 320Ah = about 4.1kWh
- 24V 100Ah = about 2.56kWh (same energy as 12V 200Ah, different shape)
- 48V 100Ah = about 5.12kWh - which is why home batteries are sold in kWh: a "10kWh wall battery" is roughly a 48V 200Ah battery in a tidy enclosure
For scale: a decent 12V compressor fridge uses roughly 0.6 to 1kWh a day, Starlink about 0.5 to 1kWh a day, and a typical NZ household uses 20 to 30kWh a day. That gap is exactly why vehicles run 100 to 320Ah batteries and houses run 10 to 30kWh banks.
12V, 24V or 48V - which world are you in?
- 12V - motorhomes, caravans, utes and small boats. Every accessory on the market runs on it. Up to about 2,000W of inverter it is the simple choice.
- 24V - bigger vans, buses and marine house banks. Half the current of 12V for the same power means smaller cables and less loss. The natural fit for 2,000 to 3,000W inverters and loads like electric trolling motors.
- 48V - homes, tiny homes, cabins and anything with a serious inverter (3kVA and up). Every modern home battery, hybrid inverter and off-grid system is built around 48V. If you are powering a building - even a tiny home - this is your voltage.
Two traps we regularly get called out to fix: chaining 12V batteries in series to make a 48V bank (mismatched charge states, no shared battery management, and in one recent case a dangerously bulging battery), and mixing battery models or generations in one bank. A proper 48V system uses purpose-built 48V batteries with their own BMS, talking to the inverter. Do it once, do it right.
12V and 24V: choosing a vehicle or marine battery
The spec sheet lines that actually matter:
- Continuous discharge current (the BMS rating). A 100A BMS supports about 1,200W of load on a 12V system. Running a 2,000W inverter or a big trolling motor? Check this number first - it is the one that catches people out.
- Cycle life at a stated depth of discharge. "6,000 cycles at 80% DoD" means something. "Long life" means nothing.
- Bluetooth monitoring. Seeing real state of charge on your phone is the difference between managing your power and guessing. All MEDA lithium batteries have it built in.
- Low-temperature charge protection. LiFePO4 must not be charged below 0 degrees C. Good batteries cut charging off automatically; cheap ones let you wreck the cells.
Charging needs gear that speaks lithium: a DC-DC charger off the vehicle alternator (a straight cable off the starter battery will not charge lithium properly and can cook your alternator), solar through an MPPT controller with a lithium profile, or a mains lithium charger for topping up at home or the marina. We size and supply all three.
Quick sizing:
- Weekend camper, fridge + lights + charging: MEDA 12V 100Ah
- Full-time vanlife, Starlink, occasional inverter use: MEDA 12V 200Ah
- Induction cooking, coffee machine, big inverter loads: MEDA 12V 320Ah
- Trolling motors and 24V house banks: MEDA 24V 100Ah or 24V 320Ah
48V: batteries for homes, tiny homes and off-grid cabins
This is the part of the market changing fastest, and the part where the right advice saves the most money. 48V batteries come in a few shapes:
- Wall-mounted batteries - the tidy option for garages and plant rooms. The Dyness Powerbox G2 (10.24kWh) is our standard home unit, and the PowerDepot G2 (5.12kWh) suits smaller loads and tiny homes. Both are modular - start with one, add more as your usage grows.
- Rack-mounted batteries - the Dyness DL5.0 (5kWh) stacks in a cabinet, which is how we build big banks: 20, 30, 40kWh and up for full off-grid homes.
- High-capacity floor units - the Dyness Powercube 6B3 (22kWh) puts serious storage in one enclosure.
- All-in-one systems - the Dyness Cygni combines a 10kW hybrid inverter and battery in a single unit, and is the heart of our Hybrid Home Power Kit.
Grid-connected home? A battery stores your solar surplus for the evening and keeps essentials running through outages. Most NZ homes use 8 to 12kWh overnight, so a 10kWh battery is the classic starting point - our Powerstore range couples storage to an existing solar system without replacing your inverter.
Off-grid home, tiny home or cabin? The battery is your grid, so sizing is done from your actual loads - typically 10 to 15kWh for a modest tiny home, 20 to 30kWh and up for full-time family living with electric cooking. Our prebuilt PowerVault cabinets and off-grid kits pair the battery bank with Victron inverters, solar and generator backup as one engineered system.
One 48V-specific spec to check: communications compatibility. A home battery should talk to its inverter (CAN bus) so charging is managed by real data, not guesswork. Every battery we sell is matched and configured to the inverter it runs with - that pairing is half the value of buying the system from one place.
Warranties - and who answers the phone
Dyness home batteries carry a 10-year warranty, Victron gear 5 years, and our workmanship is covered for 2 years on top. Just as important: MEDA is a real NZ business at 11 Cypress St, Tauranga. A 10-year warranty from an overseas web store you cannot ring is worth exactly nothing when a cell fails in year three.
Quick reference - what fits what
- Weekend camper: 12V 100Ah
- Full-time van or caravan: 12V 200Ah to 320Ah
- Boat house bank / trolling motor: 24V 100Ah+
- Tiny home: 48V, 5 to 15kWh (PowerDepot G2 / Powerbox G2)
- Grid-tied home storage: 48V, 10kWh+ (Powerbox G2, Powerstore, Cygni)
- Off-grid home: 48V, 20 to 30kWh+ (DL5.0 rack banks, PowerVault, off-grid kits)
Talk to a human
Every setup is a bit different - alternator size, cable runs, roof space, what you actually run day to day. Send us a message with what you are powering and we will tell you exactly which battery and charging setup fits, no obligation. We are MEDA, based in Tauranga - lithium power systems for vehicles, boats and buildings are all we do.