The Lithium Retrofit That Changed Our Teardown Order

Capacity and placement. A lead acid house bank was heavy enough that builders put it low and near an access door. Lithium is light enough per amp hour that installers put it wherever the space was: under a bed platform, inside a dinette base, behind a wardrobe, in a pass through bay behind other equipment. The mounting location follows convenience rather than service access.

Energy density followed. Several hundred amp hours at nominal twelve volts is a substantial store, connected through cable heavy enough to deliver very high current into a fault. Add a solar array feeding it and a DC to DC converter feeding it from the alternator, and there are three sources of energy in a vehicle whose owner will usually describe the system as just some batteries and a couple of panels.

Two reasons. First, on many installations the switch controls a distribution path and not the battery terminal, so the bank is still live at its own posts and at any busbar upstream of the switch. Finding out which is true on a given vehicle requires tracing, not assuming.

Second, lithium banks have a battery management system that opens and closes contactors on its own logic. A bank that has shut itself down on a low temperature or low voltage condition can reconnect when conditions change, which means a system that reads dead at ten in the morning may not read dead at two in the afternoon. The only acceptable confirmation is a meter reading at the point of work, taken immediately before work begins.

• A switch may control distribution rather than the battery terminal
• Busbars upstream of a switch stay live regardless of its position
• A management system can reconnect a bank without human action
• Meter at the point of work, immediately before starting

Photovoltaic panels are voltage sources in daylight. Turning off the charge controller does nothing to the panels themselves, and the conductors between the array and the controller carry voltage whenever there is light on the roof. On a series wired array that voltage can be several times the nominal battery voltage.

So the array gets addressed explicitly: either the panels are covered with opaque material, or the array conductors are disconnected at a junction and capped, before anybody works on the roof or on any structure the array wiring passes through. We have found array feeds routed through a sidewall cavity that a body repair was about to open, unfused, with no marking of any kind.

Welding current takes the lowest resistance route back to the ground clamp, and on a vehicle with electronics in it that route may pass through a control board. The rule is straightforward: the ground clamp goes as close to the weld as physically possible, on the same member, and every electronic system that can be disconnected is disconnected first.

On an aftermarket build the concern is larger than on a factory vehicle, because the installer's own grounding decisions are unknown. We have found house negative bonded to the chassis at three separate points on one van, which means welding current has three paths available and at least two of them run through wiring somebody added. Tracing the bonding before welding is now a step, not a courtesy.

There is no wiring diagram for an aftermarket build. So we photograph it: the bank and its mounting, every busbar and fuse block with the cover off, cable routing, the controller and inverter with their labels legible, and the panel with the door open. Then we note conductor sizes and fuse ratings on a sketch. Half an hour, and it is the only record that will ever exist.

This matters twice. Once during reassembly, because nobody remembers where an unlabelled conductor went three weeks later. And once on the claim, because an insurance file that includes a documented inventory of an aftermarket power system before teardown is a file where a discussion about that system's value has a starting point. Carriers ask about solar and lithium regularly now, and photographs taken before disassembly answer better than anything written afterward.

These now appear on estimates as an isolation and documentation operation. Owners occasionally query the line and the answer is easy: it is thirty to sixty minutes, it is billed at the mechanical rate, and it is what keeps a body repair from becoming an electrical event in a building with other people's vehicles in it.

1. Locate every energy storage device including the chassis battery
2. Trace what each disconnect actually controls
3. Install a temporary disconnect where no accessible one exists
4. Cover or disconnect and cap the solar array conductors
5. Confirm zero volts with a meter at the work area
6. Photograph and sketch the installation before anything comes apart