Another battery charging question

I suggest upgrading the Sunforce controller. Look at the Grape 40 amp from Home Depot.

Chargers generally play well together.

“If I need to charge my house batteries during a sunny day would it help to connect my battery tender junior?”

An adequate solar system on a sunny day doesn't need any help recharging your RV batteries.

Thanks for that concise explanation. I was just wondering actually becuase of the low amperage of the BT jr. I've use Battery Tenders for years on my batteries. I swear by them.

They will add their amps as long as the battery voltage is below the charging voltage of the two chargers. When the battery voltage rises to be equal to the voltage of one of the chargers it will "drop out" (no amps) and the other, higher voltage, charger will keep on raising the battery voltage to that charger's set voltage.

The battery tender has such low amps (being only a maintainer, not a real charger) you won't get much help there. Idling the engine for half an hour will get you more amps into the battery than that little charger can do all day.

If you have 120v to run the battery tender, then why can't you use your rig's converter? It will have lots of amps in comparison. But it must be able to get to 14.x volts same as the solar.