Battery charging service?
Pretty soon now, we'll be spending some time in an urban area with no RV parks, for work purposes. We need to run some electrical equipment off our house batteries. I thought we'd be able to recharg...
Forum Discussion
westend wrote:
On a SPST solenoid isolator, one large post is connected to the chassis battery (+) terminal, the other large post is connected to house battery (+) terminal, one small post is marked for vehicle ignition "on", one small post is to vehicle ground.
When vehicle ignition is turned on with the key, the solenoid opens and the circuit is complete between the chassis battery and the house battery. The vehicle's alternator supplies current to the chassis battery and the house batteries. When the vehicle ignition is off, the circuit to the house batteries is interrupted and no current is exchanged between house batteries and chassis battery.
This is the simplest and most reliable battery isolation switch and doesn't drop any voltage like happens with a solid state isolator. There is no worry for the vehicle's alternator to over-charge either the chassis battery or your house batteries as the alternator has it's own internal regulator. As charge increases to the house or chassis battery, the regulator lets current flow to the batteries until they are fully charged. When the batteries are fully charged the alternator's regulator interrupts the current flow to the batteries, only providing enough current to operate the vehicle.
It's advisable to install larger cable (4 ga. is good) from the battery to isolator and isolator to house batteries. You can get by with smaller cable (say, 10ga or 8ga) but with larger cable, you'll have less voltage drop and your house batteries will charge quicker.
You mentioned that sourcing wire was problematic in your area. A source of good, inexpensive, larger cable is a welding supply shop. A source of lugs to connect everything is an auto parts store. A supplier that has everything and can build cables to any length and size is Genuine deals. The isolator ignition and ground terminals can be wired with any automotive service wire in 14 ga. or larger.
That was an outstanding post! Simply stated, clear, and right to the point.
I might add that another inexpensive source of large cabling for use in RV battery setups is jumper cables available in any auto parts store. The clamps on the ends can be cut off and replaced with the heavy duty bolt-on lug connectors available in the same stores.
