14h • All About RV Batteries
Lead acid to AGM swap.
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Lead-Acid to AGM Swap – What This Looks Like in the Real World
Here’s a perfect example of the kind of battery work RV owners eventually run into.
In this case, I swapped out a set of worn, leaking lead-acid batteries and replaced them with fresh AGMs.
Nothing fancy — just solid technician steps, safety, and good habits.
Below are the general steps I followed, and these are the same habits I want YOU to start building.
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1. Take Pictures Before Touching Anything
This is the very first thing you should do on any battery job.
- Take pictures of every cable.
- Take pictures from multiple angles.
- Get close-up shots of each terminal.
Why?
Because batteries must be hooked back up EXACTLY the way they came off.
If you miss one jumper or reverse one cable, you can blow fuses, fry inverters, damage the chassis electronics, or worse.
Pictures are your insurance.
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2. Disconnect Power Safely
Before removing batteries:
- Turn OFF the battery disconnects.
- Make sure the inverter/charger is off.
- Unplug shore power.
- Turn the generator off.
Then disconnect in this order:
Negative (–) first → then Positive (+).
Reconnecting is the opposite:
Positive first → then Negative.
This reduces the chance of accidental arcing.
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3. Remove the Old Lead-Acid Batteries
As you saw in the photos, the old bank was:
- Leaking
- Corroded
- Off-gassing
- Eating into the metal tray and nearby surfaces
Lead-acid batteries do this over time — especially in RVs that see a lot of heat or sit too long without proper charging.
I removed each battery carefully and kept all jumpers laid out in the exact order they came off.
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4. Clean and Neutralize the Tray
Anytime there’s corrosion or battery acid damage, you want to clean it up before installing new batteries.
I did a light touch-up here:
- Vacuumed loose debris
- Neutralized acid residue with baking-soda solution
- Cleaned battery cables and lugs
- Wire-brushed any corrosion
- Dried everything before reinstalling
This doesn’t have to be perfect — but it DOES need to be safe and stable for the new bank.
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5. Clean and Inspect Cable Ends
Corroded cables create resistance and heat, which kills batteries and damages components.
I checked:
- Lug integrity
- Crimp tightness
- Heat-shrink condition
- Cable flexibility
- Any swollen or burnt spots
If something is questionable, this is the time to replace it — not after the batteries are in.
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6. Install the New AGM Batteries
AGMs are sealed, spill-proof, and maintenance-free.
They don’t vent acid like the old lead-acids in the pictures, which means:
- No corrosion
- No adding water
- Longer life
- Cleaner battery bay
I placed the AGMs into position, making sure all jumpers went back in the same configuration as the pictures I took earlier.
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7. Torque Terminals and Protect the Connections
After hooking everything up:
- Every terminal gets torqued snugly
- No loose or spinning lugs
- No stacking too many ring terminals on one post
- Added anti-corrosion spray for long-term protection
Good connections are everything in RV power systems.
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8. Power Up and Verify Charging
Once everything was tight:
- Turned disconnects back on
- Checked inverter/charger voltage
- Verified 13.6–14.4V charging
- Made sure the battery monitor read properly
- Tested coach DC loads
When the system reacts as expected, you know you rebuilt it correctly.
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Why This Matters for RV Owners
This entire swap teaches you a few critical habits:
- Document everything with photos
- Disconnect safely
- Respect polarity
- Clean corrosion
- Inspect cables
- Reinstall EXACTLY how you found it
- Verify charging before calling it done
You don’t have to be a technician to do the basics — but you DO need to follow the process.
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Lead acid to AGM swap.
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