1.1.1 Batteries¶
Dual battery system with AGM starter battery and LiFePO4 deep cycle auxiliary battery.
START Battery - Odyssey PC1500¶
Type: AGM Deep Cycle Battery
Model: Odyssey ODX-AGM34 (PC1500)
Manufacturer: Odyssey Battery
Product Page: Odyssey PC1500
Specifications¶
Purpose¶
Critical systems requiring high cranking amps and reliable starting:
- Engine starting (Cummins R2.8)
- PMU power (all engine bay loads)
- SafetyHub circuits
- HVAC, radiator fan
AUX Battery - Dakota Lithium 135Ah¶
Type: LiFePO4 Deep Cycle with Heated BMS
Model: DL+ 12V 135Ah Dual Purpose
Manufacturer: Dakota Lithium
Product Page: Dakota Lithium 135Ah
Specifications¶
- Capacity: 135 Ah (108 Ah usable at 80% DOD)
- Voltage: 12.8V nominal
- CCA: 1,000A equivalent
- Max Continuous Discharge: 135A
- Peak Discharge: 1,000A (2 sec)
- Dimensions: 9.5" L × 6.9" W × 8.2" H (Group 24)
- Weight: 27.2 lbs
- Cycle Life: 5,000 cycles @ 80% DOD
- Operating Temp: -4°F to 158°F (-20°C to 70°C)
- Heated BMS: Internal even-heat technology enables charging down to -4°F
Purpose¶
Accessories and high-draw auxiliary loads:
- SwitchPros lighting (up to 68A full offroad lighting)
- BODY PDU (audio, USB, heated seats)
- Winch (409A peak)
- ARB compressor (90A)
Why LiFePO4¶
| Factor | Odyssey AGM | Dakota LiFePO4 |
|---|---|---|
| Capacity | 68Ah | 135Ah |
| Usable capacity | 34Ah (50% DOD) | 108Ah (80% DOD) |
| Weight | 49.5 lbs | 27.2 lbs |
| Cycle life | 400 | 5,000 |
| Cold charging | Any temp | Heated BMS |
3× usable capacity enables 6+ hours of full night offroad lighting vs ~2 hours with AGM.
System Configuration¶
- START battery (Driver Rear Wheel Well): Odyssey PC1500 - critical systems
- AUX battery (Passenger Rear Wheel Well): Dakota Lithium 135Ah - accessories
- Isolation: BCDC Alpha 50 (independent operation when engine off)
- Jump Start: BCDC jump start assist can parallel batteries if START fails
- Redundancy: Vehicle operates on START battery alone if AUX system fails
Mounting¶
- START battery: Driver rear wheel well - enclosed compartment with access panel
- AUX battery: Passenger rear wheel well - Barnes 4WD battery box (Group 24 compatible)
Outstanding Items¶
High (3)
- JL Audio amp feed: 100A CB exceeds 4 AWG ampacity (95A @ 20°C) (#149) — The amp's battery feed is 4 AWG (95A continuous @ 20°C per the project reference table) protected by a 100A CB. The amp's internal 80A fuse is downstream and does not protect the battery-to-amp run against a chafe/short. This violates the project's "CB protects the wire" rule and is NOT covered by STANDARDS-EXCEPTIONS (which only sanctions the SwitchPros/SafetyHub 150A-on-2-AWG case).
- START+ auxiliary distribution busbar + breakers for relocated fan / iBooster / TCU (#135) — Relocating the radiator fan, iBooster, and TCU from the PMU to START-battery-direct adds three breaker-protected feeds. All three loads are forward (engine bay / transmission) while the START battery is rear, so the chosen architecture mirrors the AUX forward-feed pattern: a single master-protected feed forward to an engine-bay busbar rather than three long runs or ~9 stacked lugs on the battery post.
- Dakota Digital Panel Mounting (#39) — HDPE sheet dimensions and location for the Dakota Digital panel.
📋 Medium (10)
- 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 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
📝 Low (1)
- AUX battery− chassis-bond (rear frame rail) peak return current (#124) — Peak current through the AUX battery− → rear frame rail 2/0 chassis bond needs a proper derivation.
🔍 Verify (2)
- ARB compressor feed length: reconcile 8/10/12 ft and measure (#154) — Three different lengths are documented for the SafetyHub → ARB twin compressor feed: ~8 ft (wire-distance reference), ~10 ft (harness inventory H6), ~12 ft (SafetyHub circuit table). The SafetyHub is in the passenger rear wheel well and the compressor under the seat, so the spread doesn't change the 6 AWG sizing materially, but the figure should be measured and unified across the three files.
- Measured cable distances: START battery → relocated radiator fan / iBooster / TCU (#136) — The radiator fan, iBooster main, and TCU now feed from the START+ forward distribution busbar (engine bay) via a single master feed from the START battery (driver rear wheel well). Provisional gauges:
Build Tasks¶
- Backorder Barnes 4WD battery box (Group 24 compatible, ~$67)
- Powdercoat or paint battery box before installation
Installation Tasks: See Section 1 Installation Checklist