Short answer: on most Toyota and Lexus hybrids both chemistries drop into the same battery bay with the same connectors, so the choice is not about fitment — it is about duty. Ni-MH takes repeated high-rate cycling and extreme temperatures better; Li-ion is lighter and holds more usable capacity for its weight.
First, the thing most buyers get wrong
A replacement pack is a complete assembly. You take the original assembly out of its housing and put the replacement in. The cells inside are our choice, not the factory’s — which is why a car that left the factory with Ni-MH can run a Li-ion pack, and the other way round, as long as the pack is built for that vehicle.
That means “my car came with Ni-MH” is not by itself a reason to buy Ni-MH.
What actually differs
| Ni-MH | Li-ion | |
|---|---|---|
| Weight | Heavier for the same voltage | Lighter |
| Usable capacity | Lower | Higher for the same pack size |
| High-rate discharge | Built for it — this is what Ni-MH does well | Good, but the pack is sized for energy, not for repeated peak loads |
| Cold weather | Wide operating window; capacity still drops in extreme cold | More sensitive to very low temperatures |
| Voltage curve | Falls gradually as it discharges | Flatter under load |
| Price for a 28-module pack | $1,802 | $1,349 |
So which one?
Choose Ni-MH if:
- The car is used for towing, hill work, or repeated hard acceleration.
- It lives somewhere genuinely cold — Ni-MH holds up better at extreme low temperature.
- You want the chemistry the vehicle was engineered around.
Choose Li-ion if:
- The car does a lot of stop-start town work where usable capacity matters more than peak discharge.
- Weight matters — lighter packs are easier to handle and marginally kinder to the car.
- You want the lower price point for the same voltage.
The price surprise
Most people assume Li-ion is the premium option. On our current pricing it is not: a 28-module Ni-MH pack is $1,802 and the Li-ion equivalent is $1,349. Nickel is the expensive part of a Ni-MH cell, and that shows up in the price.
That does not make Li-ion “better” — it makes it a different tool. If your use case needs high-rate cycling, paying more for Ni-MH is the right call.
What does not change
- Both are brand-new assemblies, not refurbished.
- Both are capacity, IR and OCV matched before assembly — ΔV under 5 mV.
- Both carry the same 3-year / 100,000 km warranty.
- Neither needs coding after fitting.
Frequently asked questions
Will a Li-ion pack confuse the car’s ECU?
No. The pack presents the same voltage and interface as the original; the ECU does not care which chemistry is inside.
Does Li-ion last longer?
Both are rated above 6,000 cycles at 80% depth of discharge. Real life depends more on how the car is used and the temperatures it sees than on the chemistry label.
Can I mix — Li-ion now, Ni-MH later?
Yes. The pack is a complete assembly, so either can go into the same bay. Prices for both are here.
Frequently asked questions
Will a Li-ion pack confuse the caru2019s ECU?
No. The pack presents the same voltage and interface as the original; the ECU does not care which chemistry is inside.
Does Li-ion last longer?
Both are rated above 6,000 cycles at 80% depth of discharge. Real life depends more on how the car is used and the temperatures it sees than on the chemistry label.
Can I mix u2014 Li-ion now, Ni-MH later?
Yes. The pack is a complete assembly, so either can go into the same bay. Prices for both are here.
