Forum Discussion

nightshift's avatar
nightshift
Explorer
Sep 04, 2017

Solar regulator and aux battery charging

I recently had 300W of flex solar panels installed on my class C and man do they pump out power. I'm happy with my Blue Sky MPPT regulator since it charges the starting battery. The only problem is that this function only works when the coach batts have reached "acceptance" mode. There is no way to change this setting. We boondock most of the time and our stereo runs off the chassis battery and if it's cloudy for a couple of days the chassis batt gets a bit low.
I want to install a simple marine grade switch to connect the coach and chassis batteries. Does it matter the size of wire? Do I need a small regulator, or should I just use it like a jump starter for half an hour per day?
  • Harvey51's avatar
    Harvey51
    Explorer
    Sep 18, 2017
    I have my engine battery connected to the pair of house batteries all the time. The solar keeps them all charged. At first I disconnected them when camping but eventually forgot and no problems resulted. The wire is 14 gauge about 25 feet long so not a whole lot of current will be drawn from the house batteries when starting the engine. The engine battery has never been discharged much by the house because the solar always keeps the house batteries over 80% charged.
  • pianotuna's avatar
    pianotuna
    Nomad III
    Sep 05, 2017
    Hi,

    I installed a Trik-L-Start.


    It would also be easy to power the dash radio from the "house" bank. It does require installing an in line fuse.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Sep 04, 2017
    I agree with Mike-S. Charge the starting battery with a separate, small solar system.
  • nightshift's avatar
    nightshift
    Explorer
    Sep 04, 2017
    You're right, I should stick to standard terminology. Coach batt = house batt. Chassis batt = starting batt.

    I would prefer that the regulator would allow charging of the starting battery when the coach battery reached 80%. However, when I read the status page the "AUX BATT CHG" (aux = starting batt) stays "OFF" until the coach battery reaches 99% on the Blue Sky meter.
    At 99% charge the slow flashing green LED lets me know that "acceptance" has been reached. When I switch displays, sure enough the "AUX BAT CHG" is "ON".
  • mike-s's avatar
    mike-s
    Explorer
    Sep 04, 2017
    Starting battery, coach battery, chassis battery. Two of these things are not like the other.

    I'm only guessing that the starting battery and the chassis battery are one and the same.

    But, you say that charging the starting battery only charges when the coach battery has reached "acceptance" mode. Again, I'm only guessing that you mean absorption, which would be around 80%, so the starting battery doesn't get much charge.

    If you want both to charge, perhaps add one of the cheap PWM controllers, put one panel through that to the starting battery, and leave the other 2 panels connected to the BlueSky.
  • nightshift's avatar
    nightshift
    Explorer
    Sep 04, 2017
    OK, they have this as well. It looks like you can dial an upper and lower voltage cutoff. I'm going to call them.
  • nightshift's avatar
    nightshift
    Explorer
    Sep 04, 2017
    Yes. A few minutes ago I found something on AM Solar. They have a trickle charger(5A) for house-to-chassis charging. But I want a switch so the house batts aren't completely drained.

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