First some background: We have an RV that has two separate 12V systems.
The first is the normal chassis system that any van would have - 12V battery, alternator, engine, vehicle electronics, etc.
The second system is a totally separate (other than common ground) "coach" system, with it's own alternator, 12V AGM battery, and 350W solar w/converter, plus a bank of LiFePO4 batteries and an inverter/charger. The Lithium batteries/inverter/charger setup can be turned on or off separately, but when turned on, they are all in parallel with the coach 12V system. The idea is that when camping we run off the Lithium batteries/inverter in place of a generator for 120V AC, and going down the road the 2nd alternator also charges the Lithium batteries (when turned on). Also when plugged in to shore power, the inverter/charger will charge the Lithium (and AGM) batteries and provide 120V AC.
When sitting unused (winter), the chassis 12V system is off (like any other vehicle), the coach 12V is getting charge from the solar system, and the Lithium batteries are off. I'm not particularly happy with having the 12V AGM battery on charge all the time, but it does seem to work out OK.
Now the Question: I would like to find a circuit that trickle charges from the 12V coach system (which in daylight is always around 13.9-14V due to the solar system). to the 12V chassis system. I'm looking for a trickle charger that's limited to under 1A (open to suggestions on an actual current limit).
Can anyone suggest a circuit (or product if they're out there) that can do this? I'm looking to keep some charge in the chassis 12V battery since after a month or two parasitic loads eventually deplete the battery. Even if the circuit doesn't bring the 12V chassis system up to the full 13.9-14V that the coach system is at, it would still keep some charge in the chassis battery.
Yes, I could just put a high power diode between the two 12V systems, but then when going down the road there could potentially be significant current "siphoned off" the coach system into the chassis system, and I want to prevent that. The <1A trickle charger isn't an issue, but I want to avoid more than that.
Any help would be appreciated. Thank you.
The first is the normal chassis system that any van would have - 12V battery, alternator, engine, vehicle electronics, etc.
The second system is a totally separate (other than common ground) "coach" system, with it's own alternator, 12V AGM battery, and 350W solar w/converter, plus a bank of LiFePO4 batteries and an inverter/charger. The Lithium batteries/inverter/charger setup can be turned on or off separately, but when turned on, they are all in parallel with the coach 12V system. The idea is that when camping we run off the Lithium batteries/inverter in place of a generator for 120V AC, and going down the road the 2nd alternator also charges the Lithium batteries (when turned on). Also when plugged in to shore power, the inverter/charger will charge the Lithium (and AGM) batteries and provide 120V AC.
When sitting unused (winter), the chassis 12V system is off (like any other vehicle), the coach 12V is getting charge from the solar system, and the Lithium batteries are off. I'm not particularly happy with having the 12V AGM battery on charge all the time, but it does seem to work out OK.
Now the Question: I would like to find a circuit that trickle charges from the 12V coach system (which in daylight is always around 13.9-14V due to the solar system). to the 12V chassis system. I'm looking for a trickle charger that's limited to under 1A (open to suggestions on an actual current limit).
Can anyone suggest a circuit (or product if they're out there) that can do this? I'm looking to keep some charge in the chassis 12V battery since after a month or two parasitic loads eventually deplete the battery. Even if the circuit doesn't bring the 12V chassis system up to the full 13.9-14V that the coach system is at, it would still keep some charge in the chassis battery.
Yes, I could just put a high power diode between the two 12V systems, but then when going down the road there could potentially be significant current "siphoned off" the coach system into the chassis system, and I want to prevent that. The <1A trickle charger isn't an issue, but I want to avoid more than that.
Any help would be appreciated. Thank you.