DiploStrat
Expedition Leader
Either or ...
Based on my experience with my truck and hours of reading manuals:
-- If you want to keep your National Luna, then simply add the solar controller of your choice. This is the kind of system that I have; intelligent relay to manage the connection to the truck alternators and a solar controller, connected to the camper batteries, for solar charge. As dwh noted, when the solar charger kicks in, the intelligent relay detects the higher voltage and closes the relay, assuring that the solar charge is shared with the starting battery.
-- If you want to go CTEK, you want the CTEK D250S battery to battery charger (http://smartercharger.com/battery-chargers/#CTEK D250S DUAL) AND the CTEK SmartPass, an integrated intelligent relay. (http://smartercharger.com/battery-chargers/#CTEK SmartPass) These two devices are designed to work together. Basically, during the boost/bulk charge stage, the SmartPass closes a relay allowing up to 80A or so of charge. Once the charge rate drops to about 40A, the relay opens and the D250S continues as a smart charger through the acceptance/absorb and float stages. The great advantage of using the D250S is that it can compensate for voltage drop or low alternator voltage. If you alternator voltage is already high enough, something over 14.2v at 70F, the D250S may not be that useful. In any case, you need to be sure that your wiring is large enough to pass the full current output of your alternator over the distance between your starter and camper batteries.
If you need more than the maximum charge rate of the SmartPass, then I would recommend that you look at the Blue Sea line of intelligent relays, rated up to 500A. This is one example: https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A
Hope this helps.
Based on my experience with my truck and hours of reading manuals:
-- If you want to keep your National Luna, then simply add the solar controller of your choice. This is the kind of system that I have; intelligent relay to manage the connection to the truck alternators and a solar controller, connected to the camper batteries, for solar charge. As dwh noted, when the solar charger kicks in, the intelligent relay detects the higher voltage and closes the relay, assuring that the solar charge is shared with the starting battery.
-- If you want to go CTEK, you want the CTEK D250S battery to battery charger (http://smartercharger.com/battery-chargers/#CTEK D250S DUAL) AND the CTEK SmartPass, an integrated intelligent relay. (http://smartercharger.com/battery-chargers/#CTEK SmartPass) These two devices are designed to work together. Basically, during the boost/bulk charge stage, the SmartPass closes a relay allowing up to 80A or so of charge. Once the charge rate drops to about 40A, the relay opens and the D250S continues as a smart charger through the acceptance/absorb and float stages. The great advantage of using the D250S is that it can compensate for voltage drop or low alternator voltage. If you alternator voltage is already high enough, something over 14.2v at 70F, the D250S may not be that useful. In any case, you need to be sure that your wiring is large enough to pass the full current output of your alternator over the distance between your starter and camper batteries.
If you need more than the maximum charge rate of the SmartPass, then I would recommend that you look at the Blue Sea line of intelligent relays, rated up to 500A. This is one example: https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A
Hope this helps.
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