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ewarnerusa's avatar
ewarnerusa
Nomad
Apr 02, 2015

Charging LI bike light batteries with my camper's 12V system

I like to use my camper's 12V system to recharge various batteries because the camper is solar powered and it just gives me warm fuzzies to use that solar power for something else when I'm not camping. I do a lot of night time mountain biking and use various AA/AAA battery and li-ion battery powered lights. I've got my AA/AAA/18650 battery charger that runs off of 12V plug so I don't have to use the camper inverter. But I currently only have the 120V AC charger for my 8.4V Li-Ion battery pack that my primary light uses. I found a 12V DC charger for it; however, it only charges at half the current of the AC powered one. I realize that using the 12V DC charger will take about twice as long to recharge the battery. But my question is if the net energy requirement of charging at half the current but for twice the length of time going to be less than just using the inverter and using the 120V AC charger?
  • rexlion's avatar
    rexlion
    Explorer
    Apr 02, 2015
    Sure, the inverter will waste a little energy. But with your solar system involved, the waste would not be enough to give much thought to.
  • ewarnerusa's avatar
    ewarnerusa
    Nomad
    Apr 02, 2015
    Johno02 wrote:
    Voltage and MA on the li-ion battery??

    8.4V, 6600 mAh. Is that the info you were looking for? 12V charger is 8.4V at 0.8A. AC charger is 8.4V at 1.5A if I recall correctly.
  • ewarnerusa's avatar
    ewarnerusa
    Nomad
    Apr 02, 2015
    The 12V charger I've found is $12.27 shipped. So it is inexpensive enough to buy for the heck of it (which is what I just did!). It is true that it is one more cord to keep track of! And I don't think any payback from power savings from any of this solar powered battery recharging would ever exceed a warm fuzzy. I just know that it is desirable to avoid having to use the inverter to create 120V AC due to efficiency losses if I don't need to. If I was out camping that is and motivated to minimize energy draw from my batteries. While stored at home, the benefit would be not having to get out and walk around the camper to the storage bay where my inverters are to switch one on and having to remember to shut it off later.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 02, 2015
    I would use the inverter to avoid spending money on one more cord to keep track of.
  • MrWizard's avatar
    MrWizard
    Moderator
    Apr 02, 2015
    no way to know with out testing

    i all depends on the efficiency of design of the voltage "bucker" in the 12v charge adapter

    how much does thing cost ?
    is it worth the effort and expense, how much will you use it,
    will the power savings ( if any ) be worth the expense

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