AIMS Power's 12V LiFePO4 range is three batteries: a 104Ah in a Group 31 case, a 135Ah with RV-C communication, and a 300Ah in a Group 8D case. All three have a built-in heater, a wake-up function and Bluetooth monitoring, so the choice comes down to capacity, the battery box you have, and whether your RV talks RV-C. This guide puts the three side by side and shows how to size a bank for an RV.
The three batteries
| 12V 104Ah | 12V 135Ah | 12V 300Ah | |
|---|---|---|---|
| Model | LFP12V104A | LFP12V135A | LFP12V300A |
| Case | Group 31, 13 x 6.77 x 8.43 in | Dual-position mounting feet | Group 8D |
| Weight (AIMS) | 26.5 lb | 44 lb | Not stated |
| Energy (AIMS) | 1.38 kWh | 1.79 kWh | 3.84 kWh |
| Usable at 90% DoD (Ah x 12.8V x 0.9) | about 1,200Wh | about 1,555Wh | about 3,456Wh |
| Heater | Built in | Built in | Built in |
| Wake-up | Yes | Yes | Yes |
| Bluetooth | Yes | Yes (AIMSBATC app) | Yes |
| RV-C | Not listed | Yes | Not listed |
| Series / parallel | Yes | Yes | Yes |
| Other | IP65, fused cell design | — | — |
| Warranty (AIMS) | Lifetime, limited to 3,500 cycles | ||
Figures are from AIMS's product pages. AIMS quotes over 5,000 cycles for the 104Ah and 300Ah; the warranty term it lists for all three is lifetime, limited to 3,500 cycles (AIMS writes it as "Lifetime <3500 cycles"). The usable-energy row is our rule-of-thumb arithmetic, not an AIMS rating.
What the three features do for an RV
Built-in heater
Lithium iron phosphate cells must not be charged below freezing. The AIMS batteries warm themselves before accepting charge, so a winter trip with solar on the roof or a shore-power charger does not need a separate heating pad or a charger that knows to wait. If you camp in cold weather, this is the feature that decides lithium vs AGM; our self-heating lithium for winter camping guide covers when it matters.
Wake-up
When a LiFePO4 battery is over-discharged, its BMS opens the circuit to protect the cells, and many chargers then see 0V and refuse to charge. AIMS says its wake-up function lets the battery recover "without requiring an external jump or special charger". The AIMS PICOGLF inverter chargers also carry a lithium wake-up on the charger side, so you are covered from both ends.
Bluetooth
State of charge, voltage and current on your phone. For a whole-bank view across the inverter and solar, the 500A Bluetooth battery monitor with shunt measures everything in and out of the bank and works up to 80V, so it covers a 12V, 24V or 48V system.
RV-C on the 135Ah
RV-C is the CAN-based network many newer RVs use for their control panels. The 135Ah is the AIMS battery that lists RV-C communication, so if your coach has an RV-C display and you want the battery to report into it, this is the one to pick.
Sizing the bank
Add up a day's watt-hours: a 12V compressor fridge around 600 to 1,000Wh, lights and fans 100 to 200Wh, a laptop 150Wh, a 1,000W microwave for 10 minutes about 170Wh, a CPAP overnight 200 to 400Wh depending on humidifier use. A typical couple in a trailer lands between 1,200 and 2,500Wh a day. Then:
- About 1,200Wh a day: one 104Ah or 135Ah gets you a day; two gives you a cloudy day of margin.
- About 2,500Wh a day: two 135Ah in parallel (about 3,100Wh usable) or one 300Ah (about 3,456Wh usable).
- Running a 2000W or 3000W inverter hard: capacity is only half the question; the bank also has to deliver the inverter's current. At 12V a 2000W inverter draws about 196A at full load (2000 ÷ 12 ÷ 0.85). AIMS does not list the BMS continuous discharge current on the product pages we have, so confirm the rating for your model and bank size before pairing it with a large inverter.
The RV solar and battery calculator does this arithmetic from the loads you tick, and how big a lithium battery does your RV need goes through the trade-offs between one big battery and two smaller ones.
Will it fit the box?
The 104Ah is a Group 31 footprint, 13 x 6.77 x 8.43 in, which drops into most trailer tongue boxes and under-step battery trays that held a Group 27 or 31 lead-acid. The 300Ah is a Group 8D, the big truck-battery size, so it wants a compartment, not a tongue box. The 135Ah comes with dual-position mounting feet for flexible placement; AIMS does not give a group size for it, so measure your space against the dimensions on the listing. Group 24 vs 27 vs 31 lithium explains the case sizes.
Charging an AIMS lithium bank
- Shore power: the PICOGLF inverter chargers have a lithium charge profile (35A to 115A depending on size), and the 75A selectable 12V/24V converter charger has a LiFePO4 profile for a charger-only install. If your RV's stock converter has no lithium setting, read RV converter upgrade for lithium.
- Alternator: a stock alternator is not designed for lithium charging. The AIMS 100A and 200A lithium alternator charge regulators monitor the incoming voltage and disconnect when it leaves the safe range, with a two-wire install. Pair one with the 300A dual-sensing battery isolator, which connects the starter and house batteries above 13.2V and separates them below 12.7V, or buy both as the isolator and regulator kit.
- Solar: every AIMS charge controller, PWM or MPPT, lists a lithium profile. See AIMS PWM vs MPPT charge controllers.
FAQ
Can I mix an AIMS lithium battery with my old AGM?
Not on the same bus. Lithium and lead-acid charge at different voltages; keep a lead-acid start battery separate from a lithium house bank with an isolator or DC-DC charger. Flooded vs AGM vs lithium RV batteries explains why.
Is 104Ah really a 100Ah battery?
AIMS says it states the rated amp-hours and weight that its cells actually deliver, which is why the capacity is 104Ah rather than a round 100Ah. Treat it as a 100Ah-class battery with a little margin.
Do these ship everywhere?
AIMS lithium batteries ship from our warehouse in Upland, California to the lower 48 states. They are genuine AIMS Power and carry the AIMS Power warranty. Browse the full AIMS Power range or ask us to size the bank before you order.