How to Charge Two 6V Batteries Wired in Series
Updated 12/23/2025 | Published 01/15/2019
Question:
What size battery cables do I need to attach two 6 volt batteries 220AH together and can I use a 12 volt charger to charge or do I need a 6 volt?
asked by: LeRoy
Expert Reply:
In order to connect your two 6 volt 220Ah batteries together in series I recommend using a minimum of 4 gauge wire on each terminal. In order to charge the batteries you can use either a 6 volt or 12 volt battery charger, it all just depends on how you want to charge them. If you want to charge both together then you will need to use the battery charger in 12 volt mode (if applicable) and at the end of the series. If you want to charge each battery separately then you will need to use the battery charger in 6 volt mode (if applicable) and on each battery.
In order to charge both batteries together I recommend using the NOCO Genius On-Board Battery Charger part # 329-GEN1 which will be prefect for your two 6 volt 220Ah batteries. Please note that as you are wiring the batteries in series the voltage will double but the output (Ah) will remain the same.
I have attached a photo for you as well.
Larry
12/23/2025
What size solar for 2 6 volt batteries in series?
Continue Researching
- Search Results: leveling ramps
- Search Results: rv leveling ramps
- Q&A: How do I Improve Ride Comfort When Towing a 39' Travel Trailer with a 2025 F-350?
- Search Results: dexter ez lube seals
- Search Results: ez lube axle
- Shop: Blue Ox SwayPro Weight Distribution w/ Sway Control for 2-1/2" Hitch - 15K GTW, 1.5K TW
- Shop: B&W Continuum Weight Distribution System w/ Sway Control for 2.5" Hitch - 16K GTW, 1.6K TW
- Q&A: Replacement Axle for a 2022 Outdoors RV Back Country Series Travel Trailer
- Shop: Grease Seals - Double Lip - I.D. 1.250" / O.D. 1.983" for 2,000-lb Axles - Qty 2
- Shop: Grease Seals 10-36 - Double Lip - I.D. 2.250" / O.D. 3.376" - 5.2K to 8K Axles
- Q&A: 2015 Palomino Sabre 36QBOK Brakes and Bearing Recommendation
- Search Results: etbc7 wiring kit
- Shop: Longview Custom Towing Mirrors - Slip On - Driver and Passenger Side
- Shop: Manual-to-Electric Conversion Kit for HappiJac Truck Camper Jack Systems
- Shop: CIPA Custom Towing Mirrors - Slip On - Driver Side and Passenger Side
- Shop: Towing Mirrors
- Shop: Brake Controller
- Search Results: mirror extension
- Video: Review of HappiJac Manual-to-Electric Truck Camper Jacks Conversion Kit - LC733960-182524
- Video: Setting up the CIPA Custom Towing Mirror on a 2001 Chevrolet Silverado
- Search Results: towing mirrors
- Video: Installing the Longview Custom Towing Mirrors on your 2005 Chevrolet Silverado
- Q&A: How to Charge Two 6V Batteries Wired in Series for 12V
- Video: A Closer Look at the Optronics Trailer Clearance and Side Marker Light
- Video: Comprehensive Review: Powerbuilt Unijack
- Q&A: What is the Correct Way to Jack Up a Boat Trailer to Change a Tire
- Article: Brake Controller Installation: Starting from Scratch
- Q&A: Recommended Replacement Tire for my F78-14st Tire.
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Article: Trailer Wiring Diagrams
on Battery Charger
Russ
11/3/2024
So the 2 batteries are already connected! I don’t need to disconnect one of the two positive/negative connections BEFORE attaching the charger do I ?