DC-DC charger overload tow vehicle alternator charging lithium batteries?

kottum
kottum Member Posts: 226
edited March 2023 in Battery/Electrical & Solar
Could a DC-DC charger overload our 2021 Honda Ridgeline 155 watt alternator, charging our two 100ah Battle Born lithium batteries ?  Lower resistance than AGM or liquid cell batteries.
Douglas and Cheryl both Navy Retired
2022 Tab 320s Boondock/2021 Honda Ridgeline BE
Minnesota and Arizona

Comments

  • MarkAl
    MarkAl Member Posts: 509
    Depends on your charger. It will control charging the specific battery type and charge condition according to its rated limit.  155 watt alternator can probably output about 10 amps but that assumes nothing else in the car is pulling current - unlikely.  A 10 amp charger could be too much. I'd probably use one but worry. I have a much bigger one in my TV.
    Snohomish WA, 2015 Diesel Grand Cherokee
    Sm@ll World: 2021 320S Boondock, 6V Pb-acid
    Shunt, Roof & Remote solar & 30A DC-DC Chargers
    managed by VE Smart Network
  • kottum
    kottum Member Posts: 226
    Kind of what I thought.  I better leave the Honda Ridgeline factory charge system alone, it should charge some but is limited by resistance of the long and small wire running from alternator to the Tab batteries.
    Douglas and Cheryl both Navy Retired
    2022 Tab 320s Boondock/2021 Honda Ridgeline BE
    Minnesota and Arizona
  • WayneW
    WayneW Member Posts: 256
    edited March 2023
    That’s probably a 155 amp, not watt, alternator which I think would handle something like a 20 or 30 amp dc-dc charger fine. You do have to run heavier gauge wire to/from the charger to get decent results. I used 8 gauge wire for my Renogy 20a dc-dc charger and it works great. My TV has a 115 amp stock alternator and it puts 20a to the charger at idle without any problems. 

    Renogy has a limiting wire that you can hook up to cut output by half if you want. I have mine on a switch so I can choose what output I want, 10 or 20 amp. 
    2021 320S BD
    2017 F-150
    Coeur d'Alene, Idaho
  • carpense
    carpense Member Posts: 34
    edited August 2025
    Hi @WayneW, We have a 2021 Ridgeline. Agree, it's 155 amps (not watts). Can you help me understand how you ran the 8 gauge wire from the engine compartment to an Anderson connector at the rear? It would really help us get started. 

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