Section 1: Power Systems¶
System Overview¶
The Jeep LJ uses a dual-battery electrical system with intelligent power distribution and programmable power management.
Power Generation & Storage¶
- START battery: Odyssey PC1500 (850 CCA, 68 Ah) in driver rear wheel well - critical systems only
- AUX battery: Dakota Lithium 135Ah LiFePO4 (108 Ah usable, heated BMS) in passenger rear wheel well - accessories, winch (jump start capable)
- RedArc BCDC Alpha 50: DC-DC charger/isolator - batteries operate independently when isolated
- 270A Alternator: Charges START battery, BCDC charges AUX battery
See Power Generation for complete details on batteries, alternator, BCDC, and solar charging.
Power Distribution¶
Each battery uses a different distribution strategy:
- START battery Distribution: Inline CBs at battery (250A for PMU, 80A for BCDC input) — no local bus, direct stacked terminal lugs
- AUX battery Distribution: Inline CBs at battery (300A master forward feed + 150A SafetyHub local + 100A audio amp local) → Firewall CONSTANT Bus (Blue Sea 2105, 250A) feeds SwitchPros and BODY PDU at the firewall cluster; JL Audio MV800/8i amp fed direct from AUX battery via 100A CB
The system replaces the factory TIPM with modular programmable controllers:
- PMU24: 24-channel programmable power management - engine bay critical circuits
- BODY PDU: Cabin convenience circuits - radio, USB, heated seats, camera
- SafetyHub: High-current safety circuits - ARB compressor, winch contactor
Ground distribution architecture:
- Grounding Architecture: Battery grounds, engine bay ground bus, firewall stud bus, distributed grounding system
Wiring Standards¶
| Standard | Specification | Notes |
|---|---|---|
| Connections | Soldered + marine heat shrink | Waterproof, vibration-resistant |
| Connectors | Deutsch DT series (IP68) | Engine bay and exterior locations |
| Securing | Every 12-18" | High-vibration areas (engine bay, wheel wells, frame rails) |
| Securing | Every 24" | Low-vibration areas (cabin, trunk) |
| Loom | Split loom or braided sleeving | Abrasion protection where routed against metal |
| Grommets | Rubber with sealant | All firewall and body penetrations |
| Temp derating | 60°C for engine bay | Ampacity calculations must use derated values |
| Temp derating | 30°C for cabin/rear wheel well | Standard ampacity values acceptable |
See Wire Distance Reference for routing distances and gauge specifications.
Outstanding TBD Items¶
Auto-derived from this page's section (area/power-systems) — open GitHub issues only.
High (3)
- Passenger-side Firewall Grommet (H1) (#75) — Source single sealed 2-piece rubber grommet (Steele Rubber or equivalent) sized for ~1.5" OD H1 cable bundle (~1.75" firewall hole). Cables run continuously through - no service break. Standard winch firewall pass-through per WARN install guidance.
- Driver-side Firewall Heavy Power Grommet (#74) — Source rubber grommet sized for ~1.5" OD bundle (3x 2/0 AWG H2 cables). New firewall penetration on driver side.
- Dakota Digital Panel Mounting (#39) — HDPE sheet dimensions and location for the Dakota Digital panel.
📋 Medium (12)
- BCDC Solar (+) Terminal Size (#108) — Terminal/lug size for the RedArc BCDC Alpha 50 Solar (+) input (Yellow terminal) feeding from the Cascadia 4x4 80W panel. The solar wire gauge (10 AWG) was resolved 2026-05-30; the terminal-size column in the BCDC wiring table is still TBD (needed for lug/crimp selection).
- SwitchPros Output Wire Lengths (#107) — Wire lengths for the 12 SwitchPros SP-1200 output circuits (front/cabin/rear/roof fan-out from the firewall) are currently 'Various / TBD'. Determine once final load mounting locations are fixed.
- Radio Ground Routing (#82) — Path for 14 AWG ground wires from GMRS / Intercom (dashboard) to START battery negative (driver rear wheel well) - direct grounds required for RF noise isolation
- BODY PDU 12V Relay Part Numbers (#70) — Replacement part numbers for K40, K42, K53 (currently 24V coils)
- BODY PDU Metri-Pack Pinout (#69) — J301-J306 connector pinout (military TM or reverse engineering)
- Alternator Voltage Regulator Set Point (#68) — Verify 14.2-14.4V for AGM batteries
- Alternator Output Terminal Size (#67) — Terminal size for 1/0 AWG lug selection
- RF Power Grommet Location (#66) — Grommet 6 location near battery for radio power
- Roof/Roll Bar Routing (#64) — Light bars, dome lights
- Cab to Cargo Routing (#63) — Rear lights, compressor, lockers
- Dash to Console Routing (#62) — Switch panels, USB, radio
- Firewall Grommet Circuits (#61) — Complete wire bundle lists