Refurbished hybrid batteries

A nickel-metal hydride hybrid pack is built from modules wired in series. When one fails, the pack fails — but the other modules are often still serviceable. Refurbishing means finding the failed ones, replacing them with tested modules of matched capacity, and rebalancing the pack so it charges and discharges evenly.

That last step is the one that separates a refurbished pack from a repaired one. A pack with a fresh module dropped in beside fifteen tired ones will set a code again within months, because the new module and the old ones do not age at the same rate. Matching capacity across the pack is the work.

1. 1Every module is capacity-tested individually, under load rather than at rest. A weak module looks fine at rest — that is precisely why resting voltage tests miss them.
2. 2Modules are graded and matched, so a pack leaves as a set with a tight capacity spread rather than a collection of whatever was on the shelf.
3. 3The assembled pack is charge/discharge cycled and the block-level spread is measured again on the finished article.
4. 4Bus bars and hardware are cleaned or replaced, because corroded bus bars put resistance and heat straight into a pack you have just paid for.

We would rather lose the sale than have a pack come back. Refurbished is the wrong call in three situations, and they are worth checking before you order.

• Your vehicle uses a lithium-ion pack. Lithium packs are not module-serviceable in the way nickel-metal hydride packs are, and a “refurbished” lithium pack should make you suspicious rather than hopeful.
• Your fault is not the pack. A converter fault, an inverter cooling problem or a tired 12V battery all produce hybrid warnings, and a new pack fixes none of them.
• Your vehicle may still be inside factory hybrid coverage. Toyota's hybrid component coverage is long, and extended coverage has been issued on some inverter assemblies. Call a dealer with your VIN before you pay anyone — including us.