Forum Discussion

CoeyCoey's avatar
CoeyCoey
Explorer
Nov 04, 2018

Coach battery charger/tender.

Hello all,

I was wondering what you all do for keeping your coach battery charged? My RV didn't come with any charging for the coach battery when on shore or generator power. The coach battery always seems to go dead after a couple weeks, so I want to find a way to charge it when on shore power. Right now, I just use a battery charger plugged into the 120 and then into the cigarette lighter. But I want to install something out of sight. I am not sure what would be better. Installing a 120 volt charger and running a 12V line to the battery, or just running a 12V line from the house battery to the coach battery with a diode and a solenoid to disconnect during starting. What do you all recommend?
  • CoeyCoey's avatar
    CoeyCoey
    Explorer
    Nov 04, 2018
    BFL13 wrote:


    What is a "smart battery" ?


    It is a lithium ion battery that has a built in BMS, so it is a straight swap for a lead acid.
  • Janss's avatar
    Janss
    Explorer II
    Nov 04, 2018
    I've had Trik-L-Start on my coach for a few years. That's the little brother to Amp-L-Start recommended by pianotuna. It works great! I stay multiple months plugged in at one RV park and when ready to leave, the engine starts right up. Keeps the engine battery at 12.6 or 12.7 all the time.
  • BFL13's avatar
    BFL13
    Explorer II
    Nov 04, 2018
    CoeyCoey wrote:
    Oh, I forgot to mention, the reason I want to wire the house and coach batteries is because I want to be able to turn on the car radio and listen to it for extended periods. At present, the battery charger does not provide enough amps to do this alone, so the battery still drains. Not worried about the float voltages as the house battery is a smart battery, and also the alternator charges the house battery when driving. Currently, the charger I have is 2 amps which is higher than most battery tenders.


    Same thing in our Class C, where the entertainment system is up front and the best speakers are on the dash radio/player. I rewired the dash radio and speakers to run from the house batts, but it was a chore to route the wires.

    I still need the battery maintainer to the engine battery though.

    What is a "smart battery" ?
  • CoeyCoey's avatar
    CoeyCoey
    Explorer
    Nov 04, 2018
    Oh, I forgot to mention, the reason I want to wire the house and coach batteries is because I want to be able to turn on the car radio and listen to it for extended periods. At present, the battery charger does not provide enough amps to do this alone, so the battery still drains. Not worried about the float voltages as the house battery is a smart battery, and also the alternator charges the house battery when driving. Currently, the charger I have is 2 amps which is higher than most battery tenders.
  • BFL13's avatar
    BFL13
    Explorer II
    Nov 04, 2018
    A maintainer charger can go under the hood out of sight and be plugged into the 120 outside. Just use the clamps set of wires instead of the cig plug set.

    IMO having its own charger like that is better than paralleling the starting battery with the house battery in case they have different specified floating voltages.
  • donn0128's avatar
    donn0128
    Explorer II
    Nov 04, 2018
    Go buy a battery tender. Connect it when your parked for more than a few days.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Nov 04, 2018
    Your lifestyle (time spent off grid) type and number of batteries, is critical information which can only be supplied by your response on this forum.

    i.e. Do you spend time disconnected from a power pole?

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