How Much Battery Capacity Do You Need?
Most Tune M1 owners run a 100Ah LiFePO4 (lithium iron phosphate) battery, it covers overnight fan, lighting, and device charging with margin to spare. If you're running a 12V fridge, step up to 200Ah. A 100Ah LiFePO4 weighs approximately 29–31 lbs and costs $200–$400. The right size for your build depends on what you're running and how long you'll go between recharges:
Estimate your daily power draw
Typical M1 power draw estimates
| Load | Draw | Typical hours/day | Daily Ah |
|---|---|---|---|
| LED interior lights | ~10W (0.8A) | 4 hrs | ~3 Ah |
| Maxxair fan (low–med) | ~1.5–3A | 8 hrs | ~16–24 Ah |
| Phone + device charging | ~10W (0.8A) | 3 hrs | ~2–3 Ah |
| 12V fridge (45–50L) | ~1A avg | 24 hrs | ~25–40 Ah |
A typical M1 setup without a fridge (lights + fan + devices) draws roughly 20–30 Ah per night. Add a 12V fridge and you're looking at 50–70 Ah per day. A 100Ah LiFePO4 (80Ah usable) covers 2–3 nights without fridge, or 1–1.5 nights with fridge.
Rule of thumb sizing
- Weekend warrior (1–2 nights): 100Ah LiFePO4 is usually sufficient
- Extended trips (3–5 nights): 200Ah with solar top-up recommended
- Running a fridge full-time: 200Ah minimum; pair with at least 100W solar
LiFePO4 vs. AGM: Which Is Right for You?
| Factor | LiFePO4 | AGM |
|---|---|---|
| Usable capacity | 80–100% (don't go below 20%) | ~50% (damage below 50% DoD) |
| Weight (100Ah) | ~29–31 lbs | ~60–65 lbs |
| Lifespan | 2,000–4,000+ cycles | 200–500 cycles |
| Charge speed | Fast (accepts high current) | Slow (limited absorption rate) |
| Upfront cost (100Ah) | $293–$950 | $130–$180 |
| Long-term cost | Lower (replaces 4–8 AGMs) | Higher (frequent replacement) |
| BMS required | Yes (most come built-in) | No |
| Best for | Most M1 owners | Tight budget, occasional use |
Bottom line: If you can afford it, go LiFePO4. The weight savings alone are meaningful for payload-constrained trucks, and the effective capacity difference means a 100Ah LiFePO4 performs like a ~200Ah AGM in real-world use.
Weight & Payload Impact
This is where battery choice gets real for M1 owners. Payload is a finite resource, every pound of battery is a pound less for gear, water, and passengers.
| Battery | Weight | Usable Ah | Payload impact vs. 100Ah LiFePO4 |
|---|---|---|---|
| 100Ah LiFePO4 | ~30 lbs | ~80 Ah | — |
| 200Ah LiFePO4 | ~60 lbs | ~160 Ah | +30 lbs |
| 100Ah AGM | ~63 lbs | ~50 Ah | +33 lbs (for less usable capacity) |
| 200Ah AGM | ~120+ lbs | ~100 Ah | +90 lbs |
Upgrading from 100Ah AGM to 100Ah LiFePO4 frees up roughly 33 lbs of payload, enough for several days of food and water. On a payload-tight truck, that difference is significant.
Battery weight is one of the inputs in the M1 Builder payload calculator. Add your planned battery to your build to see its exact impact on your remaining payload margin.
Top Picks: Batteries M1 Owners Are Running
These are batteries that have been used and discussed in the M1 community, not just spec-sheet picks.
Charging Setup
A battery without a reliable charging plan will leave you in the dark. Most M1 owners use two sources: solar and the truck's alternator.
Solar charging
100W of flexible solar panel covers most non-fridge M1 setups — enough to replenish overnight fan and device usage on a typical sun day. If you're running a fridge, aim for 200W. Tune offers their own 2-panel flexible ETFE solar kit designed to fit the M1 roof cleanly. Third-party 100W flexible panels (EcoFlow, Lensun, Renogy) typically weigh 4–5 lbs each and connect via standard MC4 connectors. Always pair with an MPPT charge controller — the efficiency gains over PWM are meaningful, especially in partial shade. See the solar guide for full sizing and mounting details.
Alternator charging (DC-DC)
A DC-DC (also called B2B) charger lets your truck's alternator charge your house battery while driving. For LiFePO4, this is strongly preferred over a direct connection: lithium batteries accept charge so rapidly that a direct connection can strain or damage your alternator. The Renogy 40A (~$180–$220) is the most popular pick in the M1 community; the Victron Orion-Tr Smart 12/12-30A (~$200–$250) is the premium alternative with longer warranty and Bluetooth monitoring. A 30–40A DC-DC charger can add roughly 25–40 Ah per hour of driving, so a typical 2-hour drive can replenish most of your overnight draw.
Install Notes
The M1 doesn't have a dedicated battery bay. Common mounting approaches:
- On the camper floor at the foot of the sleeping platform, most accessible, but takes floor space
- Under the sleeping platform if your truck bed depth allows, keeps the floor clear
- In a battery box T-track-anchored to the 80/20 rail system — cleanest install, easy to pull for maintenance
Always secure the battery so it cannot shift during driving. Use appropriately sized wire (4 AWG minimum for 100Ah, 2 AWG for 200Ah at typical lengths), and fuse the positive lead as close to the battery as possible. A 100A ANL fuse is standard for most M1-scale builds.