Can You Mix the Big Jeff LI-22AH Lithium Battery with AGM Batteries?Updated 4 hours ago
Short answer: No — we don’t recommend it.
Mixing lithium and AGM batteries in the same setup without proper isolation can lead to charging problems, reduced performance, or even battery damage. Here's everything you need to know:
🔧 What Is the Big Jeff LI-22AH Battery?
The Big Jeff LI-22AH is a compact 12V lithium (LiFePO4) battery designed for car audio enthusiasts who want high performance in a small package. With its fast recharge rate, stable voltage output, and lightweight build, it's perfect for running amplifiers or supporting your electrical system without the weight of traditional batteries.
⚠️ Why You Shouldn’t Mix Lithium and AGM Batteries
Although both batteries are 12V, they operate differently in important ways:
| Feature | Lithium (Big Jeff LI-22AH) | AGM (Absorbed Glass Mat) |
|---|---|---|
| Resting Voltage | ~13.2–13.6V | ~12.6–12.8V |
| Charging Voltage | ~14.6V | ~14.2V |
| Discharge Behavior | Stable, flat curve | Gradual voltage drop |
| Internal Resistance | Low | Higher |
When mixed together:
The lithium battery may overcharge or undercharge depending on the charging system.
The lithium battery may discharge into the AGM, which can drain it quickly or cause wear.
One battery ends up doing all the work, making the setup inefficient and potentially unsafe.
✅ What to Do If You Must Use Both
If your system already includes an AGM battery (like for your starter) and you want to add a lithium battery (like the LI-22AH) for your audio setup, here’s how to do it safely:
1. Use a Battery Isolator or Voltage-Sensitive Relay
Devices like the XS Power IKXS4 or Install Bay IB500 allow you to separate the batteries so they only connect when charging.
This protects both batteries and ensures safe power delivery.
2. Charge Separately When Possible
Use a lithium-compatible charger for the Big Jeff LI-22AH.
Use an AGM-compatible charger for your lead-acid battery.
Never use the same charger for both types at the same time.
3. Monitor Your System
Regularly check your system voltage.
Use fuses and proper gauge wire for both batteries.
Make sure each battery is grounded properly to the vehicle.
🔍 Still Not Sure?
If you're unsure whether the Big Jeff LI-22AH is right for your system or how to wire it safely, reach out to our team! We're here to help with:
📞 Call or Text us at 737-BIG-JEFF (737-244-5333)
📧 Email us at [email protected]
🛒 Shop Battery Accessories
Looking for isolators, fuses, wire, or compatible chargers? Check out our full selection of power accessories here.